User Guide | McQuay refrigerant piping Application Guide 91 Pages
User Guide | McQuay refrigerant piping Application Guide
Below you will find brief information for refrigerant piping. This Application Guide was created for design engineers and service technicians to demonstrate how to size refrigerant piping. It covers R-22, R-407C, R-410A, and R-134a used in commercial air conditioning systems. It does not apply to industrial refrigeration and/or Variable Refrigerant Volume (VRV) systems. The information contained in this Application Guide is based on Chapter 2 of ASHRAE's Refrigeration Handbook and McQuay's experience with this type of equipment.
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Application Guide
Refrigerant Piping Design Guide
AG 31-011
TX Valve Mounted in Vertical Line
Sight Glass
Distributor
Solenoid
Valve
External
Equalization Line
Slope In Direction Of
Refrigerant Flow
Bulb
Suction Line
Filter-Drier
Liquid Line
Engineered for flexibility and performance.
™
2
Contents
Appendix 2 – Refrigerant Piping Tables (Inch-Pound) .............................................49
THE INFORMATION CONTAINED WITHIN THIS GUIDE REPRESENTS THE OPINIONS
AND SUGGESTIONS OF McQUAY INTERNATIONAL. EQUIPMENT, AND THE
APPLICATION OF THE EQUIPMENT AND SYSTEM SUGGESTIONS ARE OFFERED BY
McQUAY INTERNATIONAL AS SUGGESTIONS AND GUIDELINES ONLY, AND
McQUAY INTERNATIONAL DOES NOT ASSUME RESPONSIBILITY FOR THE
PERFORMANCE OF ANY SYSTEM AS A RESULT OF THESE SUGGESTIONS. THE
SYSTEM ENGINEER IS RESPONSIBLE FOR SYSTEM DESIGN AND PERFORMANCE.
Application Guide AG 31-011
Introduction
Audience
This Application Guide was created for design engineers and service technicians to demonstrate how to size refrigerant piping.
Using This Guide
This Guide covers R-22, R-407C, R-410A, and R-134a used in commercial air conditioning systems. It does not apply to industrial refrigeration and/or Variable Refrigerant Volume (VRV) systems. Illustrations and figures are not to scale. Examples showing how to perform an analysis appear in shaded outlined boxes.
How to Determine Equivalent Length
Calculate the equivalent length of the liquid line for the following condensing unit with DX air-handling unit.
The liquid line is composed of the following elements:
• 30 ft (9.14 m) of 1-3/8 inch (35 mm) piping
• 4 long radius elbows
• 1 filter drier
• 1 sight glass
• 1 globe type isolating valve
To determine the equivalent length for the refrigerant accessories use Table 4 and Table 5
Item
Long radius elbow
Filter drier
Sight glass
Globe valve
Piping
Total
Quantity
4
1
1
1
1
Dimension (ft)
2.3 (0.7m)
35 (10.7m)
2.5 (0.76m)
38 (11.6m)
30 (9.1m)
Total (ft)
9.2 (2.8m)
35 (10.7m)
2.5 (0.76m)
38 (11.6m)
30 (9.1m)
117.7 (34.96m)
Application Guide AG 31-011 3
Refrigerant Piping
Several HVAC systems require field refrigeration piping to be designed and installed on-site.
Examples include:
• Condensing units
• Direct expansion (DX) coil in air handlers
• Remote evaporators with air-cooled chillers (Figure 1)
• Chiller with a remote air-cooled condensers
Figure 1 - Typical Field Piping Application
4
The information contained in this Application Guide is based on Chapter 2 of ASHRAE's
Refrigeration Handbook and McQuay's experience with this type of equipment.
A properly designed and installed refrigerant piping system should:
• Provide adequate refrigerant flow to the evaporators, using practical refrigerant line sizes that limit pressure drop
• Avoid trapping excessive oil so that the compressor has enough oil to operate properly at all times
• Avoid liquid refrigerant slugging
• Be clean and dry
Application Guide AG 31-011
Refrigerant Piping Design Check List
The first step in refrigerant piping design is to gather product and jobsite information. A checklist for each is provided below. How this information is used will be explained throughout the rest of this guide.
Product Information
• Model number of unit components (condensing section, evaporator, etc.)
• Maximum capacity per refrigeration circuit
• Minimum capacity per refrigeration circuit
• Unit operating charge
• Unit pump down capacity
• Refrigerant type
• Unit options (Hot Gas Bypass, etc.)
• Does equipment include isolation valves and charging ports
• Does the unit have pump down?
Jobsite Information
• Sketch of how piping will be run, including: o
Distances o
Elevation changes o
Equipment layout o
Fittings o
Specific details for evaporator piping connections
• Ambient conditions where piping will be run
• Ambient operating range (will the system operate during the winter?)
• Type of cooling load (comfort or process)
• Unit isolation (spring isolators, rubber-in-shear, etc.)
☺Tip: Use this list to gather the information required to design your refrigerant piping system
Application Guide AG 31-011 5
Typical Refrigerant Piping Layouts
This section shows several typical refrigerant piping layouts for commercial air conditioning. They will be used throughout this guide to illustrate piping design requirements.
Figure 2 shows a condensing unit mounted on grade connected to a DX coil installed in a roof-
mounted air-handling unit.
1. A liquid line supplies liquid refrigerant from the condenser to a thermal expansion (TX) valve adjacent to the coil.
2. A suction line provides refrigerant gas to the suction connection of the compressor.
Figure 2 – Condensing Unit with DX Air Handling Unit
TX Valve
DX Air
Handling Unit
Suction Riser
Inverted Trap
Not Required
With
Pumpdown
Sight Glass
Air Cooled
Condensing Unit
Suction Line
Solenoid
Valve
Filter-Drier
Liquid
Line
6 Application Guide AG 31-011
Figure 3 shows a roof-mounted air-cooled chiller with a remote evaporator inside the building.
1. There are two refrigeration circuits, each with a liquid line supplying liquid refrigerant from the condenser to a TX valve adjacent to the evaporator, and a suction line returning refrigerant gas from the evaporator to the suction connections of the compressor.
2. There is a double suction riser on one of the circuits. Double suction risers are covered in
more detail in the Oil Return in Suction and Discharge Risers section of this guide (page
Figure 3 - Air-cooled Chiller with Remote Evaporator
Air Cooled Chiller
With Remote
Evaporator
Remote
Evaporator
Liquid Line
Liquid Line Riser
Double
Suction Riser
Suction Line Riser
Filter-Drier
Sight Glass
Solenoid Valve
TX Valve
Application Guide AG 31-011 7
8
Figure 4 shows an indoor chiller with a remote air-cooled condenser on the roof.
1. The discharge gas line runs from the discharge side of the compressor to the inlet of the condenser.
2. The liquid line connects the outlet of the condenser to a TX valve at the evaporator.
3. The hot gas bypass line on the circuit runs from the discharge line of the compressor to the liquid line connection at the evaporator.
Figure 4 - Indoor Chiller with Remote Air-cooled Condenser
Air Cooled
Condenser
Discharge Line Inverted
Trap (Can be Replaced With
Check Valve)
Discharge Line
Liquid Line Riser
Discharge Riser
Trap Only At Base
Hot Gas Bypass
Top Connection To
Avoid Liquid
Refrigerant Collection
Chiller
Sight Glass
Filter-Drier
Solenoid Valve
TX Valve
Application Guide AG 31-011
Piping Design Basics
Good piping design results in a balance between the initial cost, pressure drop, and system reliability. The initial cost is impacted by the diameter and layout of the piping. The pressure drop in the piping must be minimized to avoid adversely affecting performance and capacity. Because almost all field-piped systems have compressor oil passing through the refrigeration circuit and back to the compressor, a minimum velocity must be maintained in the piping so that sufficient oil is returned to the compressor sump at full and part load conditions. A good rule of thumb is a minimum of:
• 500 feet per minute (fpm) or 2.54 meters per second (mps) for horizontal suction and hot gas lines
• 1000 fpm (5.08 mps) for suction and hot gas risers
• Less than 300 fpm (1.54 mps) to avoid liquid hammering from occurring when the solenoid closes on liquid lines
Hard drawn copper tubing is used for halocarbon refrigeration systems. Types L and K are approved for air conditioning and refrigeration (ACR) applications. Type M is not used because the wall is too thin. The nominal size is based on the outside diameter (OD). Typical sizes include 5/8 inch,
7/8 inch, 1-1/8 inch, etc.
Figure 5 - Refrigerant Grade Copper Tubing
Copper tubing intended for ACR applications is dehydrated, charged with nitrogen, and plugged
by the manufacturer (see Figure 5).
Formed fittings, such as elbows and tees, are used with the hard drawn copper tubing. All joints are brazed with oxy-acetylene torches by a qualified technician.
As mentioned before, refrigerant line sizes are selected to balance pressure drop with initial cost, in this case of the copper tubing while also maintaining enough refrigerant velocity to carry oil back to the compressor.
Pressure drops are calculated by adding the length of tubing required to the equivalent feet (meters) of all fittings in the line. This is then converted to PSI (kPa).
Application Guide AG 31-011 9
10
Pressure Drop and Temperature Change
As refrigerant flows through pipes the pressure drops and changes the refrigerant saturation temperature. Decreases in both pressure and saturation temperature adversely affect compressor performance. Proper refrigeration system design attempts to minimize this change to less than 2°F
(1.1°C) per line. Therefore, it is common to hear pressure drop referred to as “2°F” versus PSI
(kPa) when matching refrigeration system components.
For example, a condensing unit may produce 25 tons (87.9 kW) of cooling at 45°F (7.2°C) saturated suction temperature. Assuming a 2°F (1.1°C) line loss, the evaporator would have to be sized to deliver 25 tons (87.9 kW) cooling at 47°F (7.2°C) saturated suction temperature.
Table 1 compares pressure drops in temperatures and pressures for several common refrigerants.
Note that the refrigerants have different pressure drops for the same change in temperature. For example, many documents refer to acceptable pressure drop being 2°F (1.1°C) or about 3 PSI (20.7 kPa) for R-22. The same 3 PSI change in R-410A, results in a 1.2°F (0.7°C) change in temperature.
Table 1- Temperature versus Pressure Drop
Refrigerant
Suction Discharge
Pressure Drop Pressure Drop
Liquid
Pressure Drop
°F (°C) PSI (kPa) °F (°C) PSI (kPa) °F (°C) PSI (kPa)
R-22
R-407C
2 (1.1)
2 (1.1)
2.91 (20.1)
2.92 (20.1)
1 (0.56)
1 (0.56)
3.05 (21.0)
3.3 (22.8)
1 (0.56)
1 (0.56)
3.05 (21.0)
3.5 (24.1)
R-410A 2 (1.1) 4.5 (31.0) 1 (0.56) 4.75 (32.8) 1 (0.56) 4.75 (32.8)
R-134a 2 (1.1) 1.93 (13.3) 1 (0.56) 2.2 (15.2) 1 (0.56) 2.2 (15.2)
Note Suction and discharge pressure drops based on 100 equivalent feet (30.5 m) and 40°F (4.4°C) saturated temperature.
Liquid Lines
Liquid lines connect the condenser to the evaporator and carry liquid refrigerant to the TX valve. If the refrigerant in the liquid line flashes to a gas because the pressure drops too low or because of an increase in elevation, then the refrigeration system will operate poorly. Liquid sub-cooling is the only method that prevents refrigerant flashing to gas due to pressure drops in the line.
The actual line size should provide no more than a 2 to 3°F (1.1 to 1.7°C) pressure drop. The actual pressure drop in PSI (kPa) will depend on the refrigerant.
Oversizing liquid lines is discouraged because it will significantly increase the system refrigerant charge. This, in turn, affects the oil charge.
Figure 2 (page 6) shows the condenser below the evaporator. As the liquid refrigerant is lifted from
the condenser to the evaporator, the refrigerant pressure is lowered. Different refrigerants will have
different pressure changes based on elevation. Refer Table 2 to for specific refrigerants. The total
pressure drop in the liquid line is the sum of the friction loss, plus the weight of the liquid refrigerant column in the riser.
Table 2 - Pressure Drop In Liquid Lines By Refrigerant
Refrigerant Pressure Drop PSI/ft (kPa/m) Riser
Only sub-cooled liquid refrigerant will avoid flashing at the TX valve in this situation. If the condenser had been installed above the evaporator, the pressure increase from the weight of the liquid refrigerant in the line would have prevented the refrigerant from flashing in a properly sized line without sub-cooling.
1
Based on saturated liquid refrigerant at 100°F (37.7°C)
Application Guide AG 31-011
It is important to have some sub-cooling at the TX valve so that the valve will operate properly and not fail prematurely. Follow the manufacturer’s recommendations. If none are available, then provide 4 to 6°F (2.2 to 3.3°C) of sub-cooling at the TX valve.
Liquid lines require several refrigerant line components and/or accessories to be field selected and
have isolation valves for servicing the basic system components, such as a condensing unit or condenser. In many cases, manufacturers supply isolating valves with their product, so be sure to check what is included. Isolating valves come in several types and shapes.
Figure 6 - Refrigerant Accessories
Aux Side
Connector
Distributor
Sight Glass
Solenoid Valve
TX Valve Filter-Drier
Referring to Figure 2 (page 6):
1. Working from the condenser, there is a liquid line filter-drier. The filter drier removes debris from the liquid refrigerant and contains a desiccant to absorb moisture in the system.
Filter driers are either disposable or a permanent with replaceable cores.
2. Next there is a sight glass that allows technicians to view the condition of the refrigerant in the liquid line. Many sight glasses include a moisture indicator that changes color if moisture is present in the refrigerant.
3. Following the sight glass is the TX valve. (More information about TX valves is available
under Thermal Expansion Valves, page 33.)
Possible accessories for this system include:
• A hot gas bypass port. This is a specialty fitting that integrates with the distributor – an auxiliary side connector (ASC).
• A pump down solenoid valve. If a pump down is utilized, the solenoid valve will be located just before the TX valve, as close to the evaporator as possible.
• Receivers in the liquid line. These are used to store excess refrigerant for either pump down or service (if the condenser has inadequate volume to hold the system charge), or as part of a flooded low ambient control approach (More information about flooded low
ambient control approach is available under Condenser Flood Back Design, page 42).
Receivers are usually avoided because they remove sub-cooling from the condenser, increase the initial cost, and increase the refrigerant charge.
Liquid lines should be sloped 1/8 inch per foot (10.4 mm/m) in the direction of refrigerant flow.
Trapping is unnecessary.
2
Photos courtesy of Sporlan Division – Parker Hannifin Corporation
Application Guide AG 31-011 11
12
Suction Lines
Suction gas lines allow refrigerant gas from the evaporator to flow into the inlet of the compressor.
Undersizing the suction line reduces compressor capacity by forcing it to operate at a lower suction pressure to maintain the desired evaporator temperature. Oversizing the suction line increases initial project costs and may result in insufficient refrigerant gas velocity to move oil from the evaporator to the compressor. This is particularly important when vertical suction risers are used. (More
Suction lines should be sized for a maximum of 2 to 3°F (1.1 to 1.7°C) pressure loss. The actual pressure drop in PSI (kPa) will depend on the refrigerant.
Suction Line Piping Details
While operating, the suction line is filled with superheated refrigerant vapor and oil. The oil flows on the bottom of the pipe and is moved along by the refrigerant gas flowing above it. When the system stops, the refrigerant may condense in the pipe depending on the ambient conditions. This may result in slugging if the liquid refrigerant is drawn into the compressor when the system restarts.
To promote good oil return, suction lines should be pitched 1/8 inch per foot (10.4 mm/m) in the direction of refrigerant flow. Evaporator connections require special care because the evaporator has the potential to contain a large volume of condensed refrigerant during off cycles. To minimize slugging of condensed refrigerant, the evaporators should be isolated from the suction line with an
inverted trap as shown in Figure 7 and Figure 8:
The trap should extend above the top of the evaporator before leading to the compressor.
1. With multiple evaporators, the suction piping should be designed so that the pressure drops are equal and the refrigerant and oil from one coil cannot flow into another coil.
2. Traps may be used at the bottom of risers to catch condensed refrigerant before it flows to the compressor. Intermediate traps are unnecessary in a properly sized riser as they contribute to pressure drop.
3. Usually with commercially produced air conditioning equipment, the compressors are “prepiped” to a common connection on the side of the unit.
4. Suction line filter driers are available to help clean the refrigerant before it enters the compressor. Because they represent a significant pressure drop, they should only be added if circumstances require them, such as after compressor burnout. In this instance, the suction filter drier is often removed after the break-in period for the replacement compressor. Suction filter driers catch significant amounts of oil, so they should be installed per the manufacturer’s specifications to promote oil drainage.
Application Guide AG 31-011
Compressor
Above Coil
Figure 7 - Remote Evaporator Piping Detail
Inverted Trap Only
Required If There Are
Evaporators Upstream
Slope In Direction of
Refrigerant Flow
Trap to Protect TX
Valve Bulb From
Liquid Refrigerant
Figure 8 - Suction Piping Details
Compressor Above Coil
No Inverted Trap
Required If
Properly Sloped
Compressor
Below Coil
Slope In Direction Of
Refrigerant Flow
Trap to Protect TX
Valve Bulb From
Liquid refrigerant
Trap Above Coil Height
Not required with
Pumpdown Systems
Trap to Protect TX
Valve Bulb From Liquid
Refrigerant
Slope In
Direction Of
Refrigerant Flow
Slope In Direction Of
Refrigerant Flow
Compressor Below Coil
Application Guide AG 31-011 13
14
100
98
96
0
106
104
102
Discharge Lines
Discharge gas lines (often referred to as hot gas lines) allow refrigerant to flow from the discharge of the compressor to the inlet of the condenser. Undersizing discharge lines will reduce compressor capacity and increase compressor work. Over sizing discharge lines increases the initial cost of the project and may result in insufficient refrigerant gas velocity to carry oil back to the compressor.
Discharge lines should be sized for no more than 2 to 3°F (1.1 to 1.7°C) pressure loss. The actual
pressure drop in PSI will depend upon the refrigerant. Figure 9 illustrates how capacity and power
consumption are affected by increasing pressure drop for both discharge and suction lines. Although these curves are based on an R-22 system, similar affects occur with other refrigerants.
Figure 9-Capacity and Performances versus Pressure Drop
Approx. Effect of Gas Line Pressure Drops on R-22 Compressor Capacity & Power – Suction Line
110
108
106
Power
104
102
100
98
96
Capacity
94
92
0 0.5
1 1.5
2
Line Loss, o
F
2.5
3 3.5
4
Approx. Effect of Gas Line Pressure Drops on R-22 Compressor Capacity & Power – Discharge Line
108
0.5
1
Power
Capacity
1.5
2
Line Loss, o
F
2.5
3 3.5
4
Application Guide AG 31-011
Discharge Line Piping Details
Discharge lines carry both refrigerant vapor and oil. Since refrigerant may condense during the off cycle, the piping should be designed to avoid liquid refrigerant and oil from flowing back into the compressor. Traps can be added to the bottom of risers to catch oil and condensed refrigerant during off cycles, before it flows backward into the compressor. Intermediate traps in the risers are unnecessary in a properly sized riser as they increase the pressure drop. Discharge lines should be pitched 1/8 inch per foot (10.4 mm/m) in the direction of refrigerant flow towards the condenser
Whenever a condenser is located above the compressor, an inverted trap or check valve should be installed at the condenser inlet to prevent liquid refrigerant from flowing backwards into the compressor during off cycles. In some cases (i.e. with reciprocating compressors), a discharge muffler is installed in the discharge line to minimize pulsations (that cause vibration). Oil is easily trapped in a discharge muffler, so it should be placed in the horizontal or downflow portion of the piping, as close to the compressor as possible.
Figure 10 - Discharge Line Piping Details
Slope In Direction Of
Refrigerant Flow
Trap at Bottom of Riser
Keep Small as Possible
Application Guide AG 31-011 15
16
Multiple Refrigeration Circuits
For control and redundancy, many refrigeration systems include two or more refrigeration circuits.
Each circuit must be kept separate and designed as if it were a single system. In some cases, a single refrigeration circuit serves multiple evaporators, but multiple refrigeration circuits should never be
connected to a single evaporator. A common mistake is to install a two circuit condensing units with a single circuit evaporator coil.
Figure 11 shows common DX coils that include multiple circuits. Interlaced is the most common.
It is possible to have individual coils, each with a single circuit, installed in the same system and connected to a dedicated refrigeration circuit.
Figure 11 - DX Coils with Multiple Circuits
While most common air conditioning applications have one evaporator for each circuit, it is possible to connect multiple evaporators to a single refrigeration circuit.
Figure 12 shows a single refrigeration circuit serving two DX coils. Note that each coil has its own
solenoid and thermal expansion valve. There should be one TX valve for each distributor.
Individual solenoids should be used if the evaporators will be operated independently (i.e. for capacity control). If both evaporators will operate at the same time, then a single solenoid valve in a common pipe may be used.
Application Guide AG 31-011
Figure 12 - Multiple Evaporators on a Common Refrigeration Circuit
Filter-Drier Liquid Line
Solenoid Valve
Sight Glass
TX Valve
Suction Line
External
Equalization
Line
Bulb mounted on Horizontal
Pipe, Close to Coil
Avoid Mounting in Traps
Slope In Direction Of
Refrigerant Flow
Trap to Protect TX
Valve Bulb From Liquid
Refrigerant
Application Guide AG 31-011 17
Sizing Refrigerant Lines
Refrigerant Capacity Tables
Appendix 2 (page 49) and Appendix 3 (page 70) provide refrigerant line sizes for commonly used
refrigerants. There is data for suction, discharge, and liquid lines. Suction and discharge lines have data for 0.5, 1, and 2°F (0.28, 0.56, and 1.7°C) changes in saturated suction temperature (SST).
Liquid lines are based on 1°F (0.56°C) changes in saturation temperature.
The data is based on 105°F (40.6°C) condensing temperature (common for water-cooled equipment) and must be corrected for other condensing temperatures (air-cooled equipment is typically 120 to
125°F (48.9 to 51.7°C)). The tables are also based on 100 feet (30.5 m) of equivalent length. The actual pressure drop is estimated based on the actual equivalent length of the application using equations in the footnotes of the refrigerant capacity tables.
☺Tip: Saturated suction temperature is based upon the pressure leaving the evaporator and represents the refrigerant temperature as a gas without superheat. The actual refrigerant temperature leaving the evaporator will be higher than this. The difference between the two temperatures is called superheat.
Equivalent Length for Refrigerant Lines
Table 4 and Table 5 in Appendix 2 (page 50) provide information for estimating equivalent lengths.
The actual equivalent length is estimated by calculating the path length in feet (meters) that the piping will follow and adding the pressure drops of the fittings and/or accessories along that length.
The tables provide pressure drops in equivalent feet of straight pipe for fittings and accessories.
For example, in Table 4, we see that a 7/8-inch (22 mm) long radius elbow has a pressure drop
equivalent to 1.4 feet (0.43 m) of straight copper pipe.
18 Application Guide AG 31-011
How to Determine Equivalent Length
Calculate the equivalent length of the liquid line for the following condensing unit with DX air-handling unit:
Liquid Line
The liquid line is composed of the following elements:
• 22 ft (6.7 m) of 1-3/8 inch (35 mm) piping
• 7 long radius elbows
• 1 filter drier
• 1 sight glass
• 1 globe type isolating valve
To determine the equivalent length for the refrigerant accessories use Table 4 and Table 5
Item
Long radius elbow
Filter drier
Sight glass
Globe valve
Piping
Total
Quantity Dimension (ft)
7
1
1
2.3 (0.70m)
35 (10.70m)
2.5 (0.76m)
1
1
38 (11.58m)
22 (6.70m)
Total (ft)
16.1 (4.90m)
35 (10.70m)
2.5 (0.76m)
38 (11.58m)
22 (6.70m)
113.6 (34.64m)
Application Guide AG 31-011 19
20
How to Size Liquid Lines
Size the refrigerant liquid lines and determine the sub-cooling required to avoid flashing at the TX valve for the condensing unit with DX air-handling unit shown in the previous example.
The system:
• Has copper pipes
• Evaporator operates at 40˚F (4.4˚C)
• Condenser operates at 120˚F (48.9˚C)
• Capacity is 60 tons (211 kW)
• Liquid line equivalent is 113.6 ft (34.64 m)
• Has a 20 ft (6.1 m) riser with the evaporator above the condenser
Step 1 – Estimate Pipe Size
To determine the liquid line pipe size for a 60 ton unit, use Table 8 in Appendix 2.
According to the table, a 1-3/8 inch (35 mm) pipe will work for a 79.7 ton (280 kW) unit.
Note, the table conditions (equivalent length and condensing temperature) are different than the design conditions.
Step 2 – Calculate Actual ΔT
Using Note 5 in the table, we can calculate the saturation temperature difference based upon the design conditions:
Δ
T
Actual
= Δ
T
Table
⎡
⎢
Actual length
Table length
⎤
⎥
⎡
⎢
Actual capacity
Table capacity
⎤
⎥
1 .
8
Δ
T
Actual
⎛
⎜ Δ
T
Actual
=
⎡
113.6 ft
⎤ ⎡
60 tons
100 ft
⎦ ⎣
79.7 tons
⎤
1.8
=
0.68
o
F
⎡
⎣
34.64m
⎤ ⎡
211kW
30.48m
⎦ ⎣ 280kW
⎤
1.8
=
0.39
o
C
⎞
⎟
Step 3 – Calculate Actual Piping Pressure Drop
According to Table 8, the pressure drop for 1˚F (0.56
o
C) saturation temperature drop with a 100 ft equivalent length is 4.75 PSI (32.75 kPa).
The actual piping pressure drop is determined using the equation
Pressure Drop
Actual
=
Pressure Drop
Table
⎛
⎜⎜
Δ
T
Actual
Δ
T
Table
⎞
⎟⎟
Pressure Drop
Actual
=
4.75PSI
⎛
0.68
o
F
1 o
F
⎞
⎠
=
3.23
PSI
⎛
Pressure Drop
Actual
=
32.75
kPa
⎛
⎜⎜
0.39
o
C
0.56
o
C
⎞
⎟⎟
=
22 .
81
kPa
⎞
Step 4 – Calculate Total Pressure Drop
Application Guide AG 31-011
Next to determine the Total pressure drop, we use Table 2 (page 10), and recall that the
riser is 20 ft. For R-410A the pressure drop is 0.43 PSI per ft (9.73 kPa/m).
Pressure drop from the riser
= Riser height ×
Refrigerant pressure drop ft
Pressure drop from the riser
=
20 ft
×
0 .
43
PSI
ft
=
8 .
6
PSI
(
Pressure drop from the riser
=
6 .
1
m
×
9 .
73
m kPa
=
59 .
35
kPa
Total pressure drop
= Actual pressure drop + Riser pressure drop
Total pressure drop
=
59 .
35
kPa
+
22 .
81
kPa
=
82 .
16
kPa
)
Step 5 – Determine the Saturated Pressure of R-410A at the TX Valve
Using refrigerant property tables which can be found in Appendix 2 of McQuay’s
Refrigerant
Application Guide (AG 31-007, see www.mcquay.com) the saturated pressure for R-410A at 120˚F is 433 PSIA (absolute) (2985 kPaA). To calculate the saturation pressure at the TX valve, we take the saturated pressure of R-410A at 120˚F and subtract the total pressure drop.
Saturated Pressure
TX Valve
=
Saturated pressure
120F
−
Total pressure drop
Saturated pressure
TX Valve
=
433
PSIA
−
11.83
PSIA
=
(
Saturated pressure
TX Valve
=
2985
kPa
−
82 .
15
kPa
421.17
PSIA
=
2902 .
85
kPa
)
Step 6 – Determine the Saturation Temperature at the TX Valve
Referring back to the Refrigeration property Tables in Application Guide 31-007, the saturation temperature at the TX valve can be interpolated using the saturation pressure at the TX valve (421 PSIA). The saturation temperature at the TX valve is found to be
117.8˚F
Step 7- Determine The Sub-cooling Required for Saturated Liquid at the TX Valve
The sub-cooling require to have saturated liquid at the TX valve can be found by:
S
ub
cooling
=
Actual saturation temperatu re
− saturation temperatu re
TX Valve
Subcooling
=
120
o
F
−
117 .
8
o
F
=
2 .
2
o
F
Step 8- Determine the Required Sub-cooling for Proper Operation
2.2˚F is the amount of sub-cooling required to have saturated liquid refrigerant at the TX valve. Anything less, and the refrigerant will start to flash and the TX valve will not operate properly. For TX valves to operate properly and avoid diaphragm fluttering, there should be an additional 4˚F of sub-cooling at the TX Valve.
Subcooling requiremen t
=
TX valve temperatu re
+
Minimum system temperatu re
Subcooling requiremen t
=
2 .
2
o
F
+
4 o
F
=
6 .
2
o
F
Application Guide AG 31-011 21
22
Refrigerant Oil
In the DX refrigeration systems covered by this guide, some amount of compressor lubricating oil travels with the refrigerant throughout the piping system. The system design must promote oil return or the compressor sump will run dry and damage the compressor.
Recall, refrigerant piping should be pitched to promote adequate oil return. Fittings and piping layout that traps and retains oil must be avoided. Compressor capacity reduction contributes to the challenge of designing the system.
For example, a screw compressor may reduce refrigerant flow (unload) down to 25%. At this reduced refrigerant flow rate, the refrigerant velocity is reduced to the point that the oil may not be pushed through the piping system and back to the compressor.
Examples of compressors that unload include:
• Scroll compressors often have multiple compressors on a common refrigeration circuit.
The circuit can unload to the smallest compressor size. For example, 4 equally sized compressors can unload down to 25%.
• Individual reciprocating compressors unload down to as low as 33%. There can be multiple compressors on a common circuit allowing even more unloading.
• Screw compressors may unload down to 25%.
Always check the manufacturer’s information to determine circuit unloading.
More piping typically requires more oil. This is particularly true for long liquid lines. Residential split systems are often pre-charged at the factory with enough oil and refrigerant for a specified line distance. When that distance is exceeded, additional refrigerant and oil will be required. For commercial split systems, the equipment may come pre-charged or it may be provided with either nitrogen or a small holding charge. The refrigerant and oil charge is then provided in the field.
To confirm if more oil is required, the system refrigerant charge must be calculated. Table 18 (page
60) through Table 21 (page 61) provide the charge per 100 feet (30.5 m) length for various
refrigerants. Generally, the oil charge should be 2 to 3% of the liquid line charge. Consult the manufacturer for the correct volume of oil in the system and the amount of oil shipped in the compressor sump. The required oil that needs to be added is the calculated total oil requirement less the oil shipped in the equipment.
Required oil
= Total oil required − oil shipped in equipment
HFC refrigerants use synthetic POE oils. These oils cannot be mixed with mineral oils. Refer to the manufacturer’s instructions for the correct type of oil to use.
Suction Line Sizing
Suction lines contain gaseous refrigerant that moves oil along the piping and back to the compressor.
Over-sizing suction pipes increases the initial costs and may reduce the refrigerant gas velocity to the point where oil is not returned to the compressor. Recall, under-sizing suction pipes reduces system capacity. Oil movement is also impacted negatively by risers, because gravity prevents oil from returning to the compressor.
Application Guide AG 31-011
Oil Return in Suction and Discharge Risers
Table 10 (page 55) through Table 17 (page 59) show minimum capacity oil return for suction and
discharge risers. When unloading capability exists, risers should be checked to verify that the minimum capacity allows for acceptable oil return. For air conditioning applications that contain less than 100 feet (30.5 m) of piping and no more than 33% capacity reduction per circuit, a properly sized riser should be found. It may be necessary to use a smaller pipe diameter for the riser, which creates a higher than desired pressure drop at full capacity, for optimal oil movement. To compensate, a larger diameter pipe may be used for horizontal runs to minimize the total pressure drop.
☺Tip: For most air conditioning applications, a single pipe riser will work. In this case, it may be necessary to undersize the riser pipe by one pipe size to provide better oil management.
Figure 13 - Proper Reduction Fittings for Risers
Install Expander in
Horizontal Pipe
Install Reducers In
Vertical Pipe
Figure 13 shows the proper method for
reducing the pipe diameter for suction and discharge risers. This approach will prevent oil from being trapped in the horizontal portion of the pipe.
Application Guide AG 31-011 23
Figure 14 - Double Suction Riser Detail
Small Diameter Pipe Inverted Trap
Not Required If Pipe Properly Sloped
Small Diameter
Riser
Slope In Direction Of
Refrigerant Flow
24
Large Diameter
Riser
Minimize Trap Volume
Figure 14 shows a double suction riser arrangement that is more common in refrigeration
applications where suction pressure drops are more critical. Most modern air conditioning applications can be met without requiring a double suction riser. Although the operation and design of a double suction riser is included in this guide, it is strongly recommended that systems be designed without a double suction riser, even if the pressure drop in the suction or discharge line is higher than desired.
In a double suction riser at full capacity, the refrigerant flow passes through both risers with enough velocity to move the oil. At minimum capacity, oil in the riser flows backward and fills the trap at the bottom. Once the trap is full of oil, refrigerant flow through the large diameter riser is cut off and only refrigerant gas flows through the smaller diameter riser. The sum of the two risers is sized for full capacity. The smaller diameter riser is sized for minimum capacity.
One of the challenges of double suction risers is that they hold a significant amount of oil within the trap. Refrigeration compressors often have larger sumps than commercial compressors, so the oil lost to the trap is less problematic for refrigeration than commercial compressors. In addition, when the capacity increases in a double suction riser, a large amount of oil is “blown” through the piping system back to the compressor. Either an oil separator or a suction accumulator (both common in refrigeration systems) may be required for a double suction riser to operate properly without causing damage to the compressor.
Application Guide AG 31-011
How to Size Suction Lines
Size the suction line with a single pipe riser and determine the pressure drop for the following air-cooled chiller with remote evaporator:
Single Pipe
Suction Riser
The system:
• Uses
• Has type L copper pipe
• Evaporator operates at 40˚F (4.4˚C) Saturated Suction Temperature (SST)
• Superheat is 10˚F (5.6˚C)
• Condenser operates at 120˚F (48.9˚C)
• Capacity is two 50 tons (176 kW) circuits with up to 20% turn down
• Suction line equivalent length for the horizontal runs is: o
Bottom 10 ft (30m) o
Top 12 ft (3.7m)
• Suction line equivalent length for a single pipe riser is 42 ft (12.8m)
Step 1- Estimate Suction Line Size
To determine the correct suction line size to operate the system at minimum capacity with a
single pipe riser use Table 7 in Appendix 2. According to the table, a 3-1/8 inch (79mm)
pipe will work for 57.1 tons (200.8kW) unit. Note, the table conditions (equivalent length and condensing temperature) are different than the design conditions.
Step 2 – Correct for Actual Operating Conditions
Sizing the pipe for full load requires a correction for the 120˚F actual condenser
temperature. Referring to the correction factors at the bottom of Table 7;
Actual capacity
=
Table capacity
×
0 .
902
Actual capacity
=
5 7 .
1
tons
×
0 .
902
=
51 .
5
tons
Application Guide AG 31-011 25
26
Step 3 – Calculate the Actual ΔT
Using Note 5 in the Table 7, calculate the saturation temperature difference based upon the
actual design conditions:
Δ
T
Actual
= Δ
T
Table
⎡
⎢
Actual length
Table length
⎤
⎥
⎡
⎢
Actual capacity
Table capacity
⎤
⎥
1 .
8
Δ
T
Actual
=
2
°
F
⎡
⎢⎣
64
100 ft ft
⎤
⎥⎦
⎡
⎢⎣
50 tons
51.5
tons
⎤
⎥⎦
1 .
8
=
1 .
2
o
F
⎛
⎝
Δ
T
Actual
=
1 .
1
°
C
⎡
⎢⎣
19.5m
30.5m
⎤
⎥⎦
⎡
⎢
176
181 kW kW
⎤
⎥
1 .
8
=
0 .
67
o
C
⎞
⎠
Step 4 – Calculate the Actual Pressure Drop
The top of Table 7 shows the pressure drop for 40˚F (4.4
o
C) saturation temperature change with a 100 ft (30.5m) equivalent length is 1.93 PSI (13.3 kPa).
Pressure Drop
Actual
=
Pressure Drop
Table
⎛
⎜⎜
Δ
T
Actual
Δ
T
Table
⎞
⎟⎟
Pressure Drop
Actual
=
1 .
93
PSI
⎛
⎜⎜
1 .
2
o
2
o
F
F
⎞
⎟⎟
=
1 .
16
PSI
⎛
⎜⎜
Pressure Drop
Actual
=
13 .
3
kPa
⎛
⎜⎜
0 .
67
o
C
1 .
1
o
C
⎞
⎟⎟
=
8 .
1
kPa
⎞
⎟⎟
A 3-1/8” pipe has 1.2˚F temperature drop and a 1.16 PSI pressure drop which is acceptable for suction pipe.
Step 5 – Confirm Oil Return At Minimum Load in The Riser
Calculate the minimum capacity
Min Capacity
= capacity
Full
×
Turn down
Min Capacity
=
50 tons
×
0.2
=
10 tons
Acutal refrigeran t temperat ure
=
SST temperatu re
+
Superheat temperatur e
Acutal refrigeran t temperat ure
=
40
o
F
+
10
o
F
=
50
o
F
Using Table 11 (page 56), 3-1/8” (79 mm) pipe and 50˚F (10
o
C) refrigerant temperature the minimum allowable capacity is 15.7 tons (55.2 kW). The table is based on 90˚F (32.2
o
C)
condensing temperature. The bottom of Table 11 has correction factors for other
condensing temperatures.
Min Allowable Capacity
Actual
=
Min Allowable Capacity
Table
×
Correction Factor
Min Allowable Capacity
Actual
=
1 5 .
7
tons
× =
12 .
6
tons
Application Guide AG 31-011
(
Min Allowable Capacity
Actual
=
55 .
2
kW
× =
44 .
16
kW
)
Since the Min allowable capacity (12.6 tons) is greater than the minimum capacity (10 tons), a 3-1/8 inch (79 mm) suction pipe is too big for minimum flow in a riser. A minimum capacity of 25 tons (88 kW) (for example, two tandem scroll compressors) would have worked with this riser.
The solution is to reduce the riser pipe one size and repeat Step 5 to confirm minimum condition is met.
We decrease the riser pipe to 2-5/8 inches (67mm) while leaving the horizontal pipes at 3-
1/8 inches. Using Table 11 we check the minimum capacity of a 2-5/8 inch (67 mm) riser.
According to the table, the minimum allowable capacity is 10.1 tons (35.5 kW) at 90˚F
(32.2
o
C) condenser temperature.
Min Allowable Capacity
Actual
=
Min Allowable Capacity
Table
×
Correction Factor
Min Allowable Capacity
Actual
=
1 0 .
1
tons
× =
8 .
1
tons
The minimum allowable capacity is now less than the minimum capacity so a 2-5/8 inch (97 mm) riser is sufficient for this system.
Step 6 – Calculate the Suction Line Pressure Drop With the New Riser Size
Suction line pressure drop is the sum of the 3-1/8 inch (79 mm) horizontal piping and the 2-
5/8 inch (97mm) vertical piping.
The equivalent length of the vertical pipe is given at 42 ft (12.8m). According to Table 7
(page 52), the capacity for a 2-5/8 inch (97mm) line is 35.8 tons (125.87 kW). To calculate
the vertical pipe suction line temperature drop use Note 3 in Table 7;
Corrected vertical suction line capacity
=
Table capacity
×
0 .
902
Corrected vertical suction line capacity
=
35 .
8
tons
×
0 .
902
=
32 .
3
tons
Δ
T
Actual Vertical
= Δ
T
Table
⎡
⎢
Actual length
Table length
⎤
⎥
⎡
⎢
Actual capacity
Table capacity
⎤
⎥
1 .
8
Δ
T
Actual Vertical
=
2 o
F
⎡
42
⎢⎣
100 ft ft
⎤
⎥⎦
⎡
⎢
50
32.3
tons tons
⎤
⎥
1 .
8
=
1 .
84
o
F
⎛
⎝
Δ
T
Actual Vertical
=
1 .
1 o
C
⎡
⎢⎣
12.8m
30.5m
⎤
⎥⎦
⎡
⎢
175.9
113.6
kW kW
⎤
⎥
1 .
8
=
1 .
01
o
C
⎞
⎠
The top of Table 7 shows the pressure drop for 40˚F saturation temperature change with a
100 ft equivalent length is 1.93 PSI (13.3 kPa).
Pressure Drop
Actual Vertical
=
Pressure Drop
Table
⎛
⎜⎜
Δ
T
Actual Vertical
Δ
T
Table
⎞
⎟⎟
Pressure Drop
Actual Vertical
=
1.93
PSI
⎛
⎝
1.84
o
F
2
o
F
⎞
⎠
=
1.78
PSI
Application Guide AG 31-011 27
⎛
Pressure Drop
Actual Vertical
=
13 .
3
kPa
⎛
⎜⎜
1 .
01
o
1 .
1
o
C
C
⎞
⎟⎟
=
12 .
21
kPa
⎞
The same approach is used again to calculate the horizontal 3-1/8” piping. In this case the equivalent length of horizontal piping was 22 ft (6.7m).
Δ
T
Actual Hor
⎡
⎣
22 ft
⎤ ⎡
⎦ ⎣
50 tons
100 ft
⎥ ⎢
51.5 tons
⎤
1.8
=
0.42
o
F
⎛
⎜ Δ
T
Actual Hor
=
1.1 C
⎡
⎣
6.7m
30.5m
⎤
⎥
⎦ ⎣
⎡
⎢
176kW
181kW
⎤
1.8
=
0.23
o
C
⎟
⎠
⎞
⎟
Pressure Drop
Actual Hor
=
1 .
93 PSI
0 .
42
°
F
2
°
F
=
0 .
41
PSI
⎛
⎜⎜
Pressure Drop
Actual Hor
=
13 .
3 kPa
0 .
23
°
C
1 .
1
°
C
=
0 .
2 .
78
kPa
⎞
⎟⎟
Pressure drop
Total
=
Pressure drop
Vertical
+
Pressure drop
Hor
Pressure drop
Total
=
1.78
PSI
+
0.41
PSI
=
2.19
PSI
Pressure drop
Total
=
12 .
21
kPa
+
2 .
78
kPa
=
14 .
99
kPa
28 Application Guide AG 31-011
How to Size a Suction Line Double Riser
Size a double suction riser for the following air-cooled chiller with remote evaporator:
Double Suction Riser
The system:
• Uses
• Has type L copper pipe
• Evaporator operates at 40˚F (4.4˚C) Saturated Suction Temperature (SST)
• Superheat is 10˚F (5.6˚C)
• Condenser operates at 120˚F (48.9˚C)
• Capacity is two 50 ton (176 kW) circuits with up to 20% turn down
• Suction line equivalent length for the horizontal runs is: o
Bottom 10 ft (3.0m) o
Top 12 ft (3.7m)
• Equivalent Length is 64 ft (19.5m)
• Horizontal pipe size is 3-1/8 inch (79mm) (from previous example)
Step 1 – Estimate Minimum Capacity
Minimum Capacity
=
50
tons
×
20 %
=
10
tons
(
Minimum Capacity
=
176
kW
×
20 %
=
35 .
2
kW
)
Step 2 – Estimate Small Riser Size
To determine the small riser line size to operate the system at minimum capacity use
According to the table, a 2-1/8 inch (54mm) pipe will work for a 20.2 ton (71.0 kW) unit.
Note, the table conditions (equivalent length and condensing temperature) are different than the design conditions.
Application Guide AG 31-011 29
Step 3 – Correct for Actual Operating Conditions
Sizing the pipe for full load requires a correction for the 120˚F (48.9˚C) actual condenser
temperature. Referring to the correction factors at the bottom of Table 7;
Actual capacity
=
Table capacity
×
0 .
902
Actual capacity
=
20 .
2
tons
×
0 .
902
=
18 .
2
tons
(
Actual capacity
=
71.0
kW
×
0.902
=
64.0
kW
)
Step 4 – Size Large Riser
At full capacity the cross sectional area of the two risers should equal the original riser area
(in this example a 3-1/8 inch pipe). Use Table 11 (page 56) to determine the area of the
pipes.
Large diameter riser
= Area original pipe − Area small pipe
Large diameter riser
=
Area
3 1/8 inch pipe
−
Area
2 1/8 inch pipe
Large diameter riser
(
Large diameter riser
=
=
6 .
812
43 .
95
in
2
cm
2
−
3 .
095
in
2
−
19 .
97
cm
2
=
3 .
717
in
2
=
23 .
98
cm
2
)
Using Table 11 we see that 3.717 square inches is between a 2-1/8 inch (54mm) riser and
a 2-5/8 inch (67mm) riser. Using a 2-5/8 inch riser will reduce the pressure drop. So the small riser should be 2-1/8 inches and the large riser should be 2-5/8 inches.
30 Application Guide AG 31-011
Discharge Line Sizing
Discharge lines contain gaseous refrigerant that moves the oil along the piping back towards the compressor. Oversized discharge lines increase the initial cost and can reduce the refrigerant gas velocity to a point where oil is not returned to the compressor. Undersized discharge lines reduce system capacity. Oil movement in discharge lines is further complicated by risers, where gravity is working against oil return.
How to Size a Discharge Line
Size minimum capacity discharge line for a single riser and the pressure drop for the following indoor process chiller with remote air-cooled condenser:
Discharge Line
The system:
• Uses
• Has type L copper pipe
• Evaporator operates at 20˚F (-6.7˚C) Saturated Suction Temperature
• Superheat is 15˚F (5.6˚C)
• Condenser operates at 110˚F (48.9˚C)
• Discharges at 140˚F (60˚C)
• Capacity is 250 tons (176 kW) circuits with up to 33% turn down
• Discharge line equivalent length for the horizontal runs is: o
Bottom 15 ft (4.6m) o
Top 10 ft (3.0m)
• Single pipe riser discharge line equivalent is 110 ft (33.5m)
Step 1 – Estimate the Discharge Line Size
To determine the discharge line pipe size for a 250 ton (211 kW) unit use Table 6 in
. According to the table, a 4-1/8 inch (105mm) pipe will work for a 276.1 ton
(970 kW) unit with 20˚F (-6.7
o
C) Saturated Suction Temperature. Note, the table conditions
(equivalent length and condensing temperature) are different than the design conditions.
Application Guide AG 31-011 31
32
Step 2 – Correct For Actual Operating Conditions
Sizing the pipe for full load requires a correction for the 110˚F (43.3˚C) actual condenser temperature. Referring to the correction factors at the bottom of Table 6;
Actual capacity
=
Table capacity
×
1 .
04
Actual capacity
(
Actual capacity
=
=
276 .
1
tons
×
1 .
04
970 kW
×
1.04
=
287
tons
=
1009 kW
)
Step 3 – Calculate the Actual ΔT
Using Note 5 in the table, we can calculate the saturation temperature difference based upon the actual design conditions:
Δ
T
Actual
= Δ
T
Table
⎡
⎢
Actual length
Table length
⎤
⎥
⎡
⎢
Actual capacity
Table capacity
⎤
⎥
1 .
8
Δ
T
Actual
⎛
⎝
Δ
T
Actual
=
1
°
F
⎡
⎢⎣
110
100 ft ft
⎤
⎥⎦
⎡
⎢⎣
250 tons
287 tons
⎤
⎥⎦
1 .
8
=
0 .
56
°
C
33.5m
30.5m
=
⎛
⎜⎜
879
1009
kW kW
0 .
86
o
F
⎞
⎟⎟
1 .
8
=
0 .
48
o
C
⎞
⎠
Step 4 – Calculate the Actual Pressure Drop
The top of Table 6 shows the pressure drop for 1˚F (0.56
o
C) saturation temperature change with a 100 ft equivalent length is 3.05 PSI.
Pressure Drop
Actual
=
Pressure Drop
Table
⎛
⎜⎜
Δ
T
Actual
Δ
T
Table
⎞
⎟⎟
Pressure Drop
Actual
=
3 .
05 PSI
0 .
86
°
F
1
°
F
=
2 .
62
PSI
Pressure Drop
Actual
=
21.03
kPa
⎛
⎝
0.48
0 .
56 o
o
C
C
⎞
⎟⎟
=
18 .
03
kPa
A 4-1/8” pipe has 0.86˚F temperature drop and a 2.61 PSI pressure drop which is acceptable for discharge pipe.
Step 5 – Confirm Oil Return At Minimum Load In Riser
Next we evaluate whether the riser size will provide acceptable oil return at minimum load.
Minimum capacity
=
Actual unit capacity
×
Turn down
Minimum capacity
(
Minimum capacity
=
=
2 50
879 tons
× kW
×
0.33
0.33
=
=
82.5
290 tons kW
)
The actual discharge refrigerant temperature and condensing temperature are given as
140˚F and 110˚F respectively. The actual SST and superheat are given as 20˚F and 15˚F respectively.
Using Table 14 (page 57) with the above given conditions, the minimum allowable capacity is
62 tons (218 kW). Since the minimum system capacity (82.5 tons) is greater than the minimum riser capacity (62 tons) the riser is acceptable as designed.
Had the riser been too large for the minimum system capacity, the discharge riser should have been decreased one pipe size and Step 5 repeated until an acceptable size was found.
Application Guide AG 31-011
Thermal Expansion Valves
Expansion valves are used to modulate refrigerant flow to the evaporator. There are several types of expansion valves including:
• Fixed area restrictor (capillary and orifice types)
• Automatic (constant pressure)
• Thermal expansion (TX)
• Electronic
For field-piped systems, the TX and electronic types are commonly used. Electronic valves require significant controls to operate and normally are used if they were included as part of the original equipment.
Figure 15 - Thermal Expansion Valve
TX valves (Figure 15) are excellent for DX systems
because they modulate refrigerant flow and maintain constant superheat at the evaporator. As superheat climbs, the TX valve opens allowing more refrigerant to flow. As superheat drops, the valve closes to maintain superheat.
TX valves are sized by:
• Refrigerant type
• Refrigeration circuit capacity
• Pressure drop across the valve
• Equalization (internal or external)
For smaller systems, an internally equalized TX valve is acceptable. For larger systems (greater than 2 PSI
(13.8kPa) pressure drop across the evaporator, or if a distributor is used) an externally equalized TX valve is recommended. An external line accounts for the pressure drop through the evaporator which becomes an issue on larger evaporator coils.
TX valves and distributors (common with air coils) should be installed in vertical pipes. If a TX valve with a distributor is installed in a horizontal pipe, there is a possibility that the liquid portion of the two-phase flow downstream of the TX valve will fill the distributor tubes on the bottom, leading to different refrigerant flow rates in the individual tubes. This is not an issue with nozzles (common with chillers), so horizontal installations are acceptable.
3
Photos courtesy of Sporlan Division – Parker Hannifin Corporation
Application Guide AG 31-011 33
34
TX valves should be sized as close to capacity as possible. Use of nominal TX valve capacity is discouraged. Follow the manufacturer’s selection procedures and select the valve for the actual operating conditions. Under-sizing up to 10% is acceptable if there will be significant part load operation. Higher superheat conditions at full load are allowable.
There must be one TX valve for each distributor. For large DX field applications there are often multiple refrigeration circuits, each with its own compressor, evaporator circuit, and TX valve.
Evaporator circuits may be in a common evaporator coil such as interlaced, face split, or row split
type (For more information about evaporator circuits see Multiple Refrigeration Circuits, page 16).
On occasions where there are multiple evaporators on a common refrigeration circuit, separate TX valves and solenoid valves are required for each evaporator.
Figure 16 shows a typical TX valve installation.
1. The sensing bulb is strapped to the suction line on the top (12 o’clock) for line sizes under
7/8 inch (22 mm) and at 4 or 8 o’clock for larger line sizes. The bulb should be tightly strapped to a straight portion of the suction line and insulated unless it is in the leaving air stream.
2. The equalization line should be downstream of the bulb. Refer to manufacturer’s installation instructions for specific details.
3. Neither the bulb nor the equalization line should be installed in a trap.
Figure 16 - Typical TX Valve Installation
TX Valve In
Vertical Pipe
Sight Glass
Solenoid Valve
Liquid Line
Distributor
External Equalization
Line
Bulb
Suction Line
Filter-Drier
Application Guide AG 31-011
Hot Gas Bypass
Hot gas bypass is a method of maintaining compressor suction pressure (creating a false load) during light loads. This has the affect of modulating compressor capacity below the minimum unloading point without cycling the compressor. It is accomplished by returning hot (discharge) gas from the leaving side of the compressor back to a point on the low-pressure side of the refrigeration circuit.
Figure 17 shows the preferred method for piping hot gas bypass. Hot gas is introduced into the inlet
of the evaporator and is given ample time to distribute its energy into the main flow of refrigerant prior to returning it to the compressor. A special fitting called an Auxiliary Side Connector (ASC) should be used to introduce the hot gas into the distributor. In addition, the distributor may need a different nozzle. On DX coils that have a venturi, a standard copper tee fitting may be used to introduce the hot gas.
☺Tip: McQuay DX coils use distributors that require an ASC and the nozzle in the distributor needs to be changed. DX coils that use a venturi introduce hot gas bypass using a standard tee fitting.
Figure 17 - Typical Hot Gas By-pass Piping Arrangement
Hot Gas Routed
Above Evaporator
Liquid Line
Hot Gas Bypass Solenoid
Valve Installed Close To
Discharge Line
Hot Gas Bypass
Valve Installed
Close To
TX Valve
Suction Line
Auxiliary Side Connector
(ASC) Introduces Hot Gas Into
Distributor
Evaporator
Discharge Line
Hot gas bypass lines include a solenoid valve and a hot gas bypass valve. Some manufacturers provide a single device that provides the functions of both a solenoid and control valve. The solenoid valve is energized when hot gas bypass is required. The hot gas bypass valve modulates the refrigerant flow through the line to maintain the suction pressure.
Hot Gas Bypass Line Sizing
Hot gas piping should be sized using the discharge gas line sizing tables found in Appendix 2 (page
volume. During off cycles, the vapor refrigerant will condense and may create a slug of refrigerant
Application Guide AG 31-011 35
36 when the hot gas bypass valve opens. A rule of thumb is use one line size smaller than the recommended discharge table line size because hot gas bypass lines are short. Once the line size is selected, the actual temperature and pressure drop should be checked. The line pressure drop should be small relative to the pressure drop across the valve. The line should be pitched 1/8 inch per foot
(10.4 mm/m) in the direction of refrigerant flow.
The hot gas bypass valve and solenoid should be located as close to the discharge line as possible.
This will minimize the amount of hot gas that may condense upstream of the valve and solenoid.
The hot gas bypass line should be routed above the evaporator and introduced to the ASC from the side to reduce oil scavenging. The line should be insulated and a check valve added if the ambient temperature is lower than the saturated suction temperature.
Hot Gas Bypass Valves
Hot gas bypass (HGBP) valves used with distributor-type DX coils should be externally equalized.
Their purpose is to maintain minimum suction pressure to the compressor. This is best done when the valve is responding to suction pressure. Over sizing the HGBP valve may cause:
• System inversion
• Loss of oil management
• Prevent the compressor from cycling off (overheating)
• Poor efficiency
Hot gas valve selection is based on;
• Refrigerant type
• Minimum allowable evaporating temperature at reduced load – typically 32 to 34°F (0.0 to
1.1°C) for chillers and 26 to 28°F (-3.3 to -2.2°C) for air conditioners
• Minimum compressor capacity
• Minimum system capacity. For air conditioning applications, minimum load with hot gas bypass use should be limited to approximately 10% of a system's capacity. Some process applications will require unloading down to zero
•
Condensing temperature at minimum load – typically 80°F (26.7°C).
Figure 18 - Hot Gas By Pass
Accessories
Hot gas bypass valves must be sized for the difference between the minimum compressor capacity and the minimum system capacity. If the minimum system capacity is zero, then the hot gas bypass valve should be sized for the minimum compressor capacity.
The example provided here is based on
Sporlan products. For other manufacturers, refer to their installation and application guides.
Sporlan valves begin to open at approximately 6°F (3.3°C) above the minimum evaporator temperature and remain open at the rated capacity of the minimum evaporator temperature. The actual pressure which the valve will open at depends on the refrigerant.
When remote condensers are used, always layout and size the condenser piping before selecting the
HGBP valve. During light loads, when the HGBP valve is open, the remaining velocity in the discharge line may be so low that oil becomes trapped.
4
Photos courtesy of Sporlan Division – Parker Hannifin Corporation
Application Guide AG 31-011
Figure 19 - HGBP Valve Sizing Chart
Direct Acting Discharge Bypass Valve Capacities (tons)
Capacities based on discharge temperatures 50 o
F above isentropic compression, 25 o
F superheat at the compressor, 10 o
F sub-cooling, and includes both the hot gas bypassed and liquid refrigerant for desuperheating, regardless of whether the liquid is fed through the system thermostatic expansion valves or an auxiliary desuperheating thermostatic expansion valve.
Minimum Allowable Evaporator Temperature At The Reduced Load ( o
F)
40 26 20 0 -20 -40
Condensing Temperature ( o
F)
80 100 120 80 100 120 80 100 120 80 100 120 80 100 120 80 100 120
22
ADRI-1-1/4
ADRIE-1-1/4
ADRS-2
ADRSE-2
ADRP-3
ADRPE-3
ADRHE-6
ADRI-1-1/4
ADRIE-1-1/4
Adjustable Models
0/55 - - - 0.34 .044 0.56 0.41 0.52 0.66 0.49 0.63 0.79 0.46 0.59 0.75 0.43 0.56 0.70
0/75 0.45 0.58 0.73 0.50 0.64 0.81 0.50 0.65 0.81 0.47 0.60 0.76 0.39 0.50 0.63 0.33 0.42 0.54
0/100 0.41 0.53 0.67 0.42 0.54 0.67 0.41 0.53 0.66 0.38 0.49 0.62 0.34 0.44 0.56 0.31 0.40 0.50
0/30 - - - - - - - - - 3.02 3.90 4.91 2.91 3.75 4.74 2.81 3.63 4.58
0/80 2.73 3.51 4.42 2.77 3.57 4.50 2.79 3.59 4.53 2.84 3.66 4.61 2.83 3.65 4.60 2.71 3.50 4.42
0/30 - - - - - - - - - 10.8 13.9 17.6 10.9 14.1 17.8 10.5 13.5 17.1
0/80 7.12 9.16 11.5 7.69 9.90 12.5 7.92 10.2 12.8 8.44 10.9 13.7 8.55 11.0 13.9 8.24 10.6 13.5
0/30 - - - - - - - - - 10.8 13.9 17.6 10.9 14.1 17.8 10.5 13.5 17.1
0/80 7.12 9.16 11.5 7.69 9.90 12.5 7.92 10.2 12.8 8.44 10.9 13.7 8.55 11.0 13.9 8.24 10.6 13.5
0/55 0.30 0.40 0.51 0.31 0.41 0.53 0.31 0.41 0.53 0.29 0.38 0.49 - - - - - -
0/75 0.32 0.43 0.55 0.30 0.39 0.50 0.28 0.37 0.48 0.23 0.31 0.40 - - - - - -
0/100 0.26 0.34 0.44 0.24 0.32 0.41 0.24 0.31 0.40 0.21 0.28 0.36 - - - - - -
0/30 - - - 1.97 2.60 3.34 1.94 2.56 3.30 1.87 2.46 3.18 - - - - - -
134a
ADRS-2
ADRSE-2
ADRP-3
ADRPE-3
0/30 - - - 3.75 4.95 6.38 3.76 4.96 6.39 3.70 4.89 6.31 - - - - - -
0/30 - - - 7.09 9.36 12.1 7.09 9.37 12.1 7.12 9.41 12.1 - - - - - -
ADRHE-6
ADRI-1-1/4
ADRIE-1-1/4
0/55 - - - 0.48 0.61 0.77 0.54 0.69 0.86 0.58 0.74 0.93 0.53 0.68 0.85 - - -
0/75 0.61 0.78 0.97 0.61 0.78 0.97 0.60 0.77 0.96 0.53 0.68 0.85 0.43 0.56 0.69 - - -
0/100 0.51 0.65 0.81 0.50 0.63 0.79 0.48 0.62 0.77 0.44 0.56 0.70 0.39 0.50 0.62 - - -
407C
ADRS-2
ADRSE-2
ADRP-3
ADRPE-3
0/80 3.32 4.25 5.30 3.32 4.25 5.30 3.33 4.27 5.32 3.36 4.31 5.38 3.30 4.23 5.28 -
0/80 5.86 7.50 9.36 5.86 7.50 9.36 5.95 7.61 9.50 6.10 7.81 9.75 6.02 7.71 9.63 -
-
-
-
-
ADRHE-6
0/80 9.43 12.1 15.1 9.43 12.1 15.1 9.67 12.4 15.5 10.1 13.0 16.2 10.1 12.9 16.1 - - -
5
This table courtesy of Sporlan Division – Parker Hannifin Corporation. It is only included for the example. Please refer to manufacturers data for sizing and application.
Application Guide AG 31-011 37
How to Size a Hot Gas Bypass Line
Size the hot gas bypass line and valve for the following air conditioner:
The system:
• Uses
• Capacity is a 30 ton air conditioner with tandem scroll compressors
• Minimum capacity is 5 tons (17.6 kW)
• Minimum compressor capacity of 15 tons (52.8 kW) or one compressor
• Evaporator operates at 26˚F (-3.3˚C)
• Condenser operates at 120˚F (48.9˚C) that drops to 80˚F (26.7˚C) during minimum load
• Equivalent length is 10 ft (3.0m)
Step 1 – Estimate HGBP Valve Capacity
HGBP valve
= Minimum compressor capacity − Minimum system capacity
HGBP valve
−
5 tons
=
10 tons
(
HGBP valve
=
52.8
kW 17.6
kW
=
35.2
kW
)
Step 2 – Select a HGBP Valve
(page 37) shows the Sporlan Rating table for ADRHE series of HGBP valves.
Given a 10 ton capacity, 26˚F evaporator temperature, 80˚F condensing temperature we can see a ADRHE-6 can deliver 9.43 tons (33.1 kW) and can use a 5/8, 7/8, or 1-1/8 inch solder connection.
Step 3 – Estimate HGBP Piping Size
(page 54) can be used to determine the hot gas bypass line size for R-407C. For
10 tons 1-1/8 inch line delivers 8.5 tons (29.8 kW) at 20˚F (-6.67˚C) SST and table rating conditions. The equivalent length of this application is only 10% of the table rating condition. A 1-1/8-inch (29mm) pipe will deliver much more capacity at such a short length. Let’s consider a 7/8-inch (22mm) line which delivers 4.2 tons (14.7 kW).
38 Application Guide AG 31-011
Sizing the pipe for full load requires a correction for the 80˚F (26.7˚C) actual condenser
temperature. Referring to the correction factors at the bottom of Table 9;
Actual capacity
=
Table capacity
×
0 .
787
Actual capacity
=
4 .
2
tons
×
0 .
787
=
3 .
31
tons
(
Actual capacity
=
14.8
kW
×
0.787
=
11.65
kW
)
Step 4 – Calculate the Actual ΔT
Using Note 5 in the table, we can calculate the saturation temperature difference based upon the actual design conditions:
Δ
T
Actual
= Δ
T
Table
⎡
⎢
Actual length
Table length
⎤
⎥
⎡
⎢
Actual capacity
Table capacity
⎤
⎥
1 .
8
Δ
T
Actual
=
1
°
F
⎡
⎢⎣
10
100 ft ft
⎤
⎥⎦
⎡
⎢⎣
10 tons
3.31
tons
⎤
⎥⎦
1 .
8
=
0 .
732
o
F
⎛
⎝
Δ
T
Actual
=
0 .
56
°
C
⎡
⎢⎣
3.0m
30.5m
⎤
⎥⎦
⎡
⎢
35.2
11.7
kW kW
⎤
⎥
1 .
8
=
0 .
40
o
C
⎞
⎠
Step 5 – Calculate the Actual Pressure Drop
The top of Table 9 shows the pressure drop for 1˚F (0.56
o change with a 100 ft equivalent length is 3.3 PSI.
C) saturation temperature
Pressure Drop
Actual
=
Pressure Drop
Table
⎛
⎜⎜
Δ
T
Actual
Δ
T
Table
⎞
⎟⎟
Pressure Drop
Actual
=
3.3 PSI
⎛
⎝
⎞
⎠
=
2.42
PSI
⎛
⎜⎜
Pressure Drop
Actual
=
22 .
8
kPa
⎛
⎜⎜
0 .
40
o
C
0 .
56
o
C
⎞
⎟⎟
=
16 .
3
kPa
⎞
⎟⎟
A 7/8-inch (22mm) line provides a satisfactory pressure drop and keeps the line volume to a minimum. For point of comparison, a 1-1/8 inch (29mm) line would have provided a pressure drop of 0.65 PSI (4.48 kPa). This would have been an acceptable pressure drop, but the volume would have been greater. A 5/8-inch (16mm) line would have had a
13.5 PSI (93.1 kPa) drop and the refrigerant velocity would have caused excessive noise.
In addition to the HGBP valve we require:
• A 7/8 inch (22mm) solenoid
• An ASC for the distributor
• A new nozzle for the distributor
Recall that the HGBP valve begins to open at 6˚F (3.3˚C) above SST, or in this case 32˚F
(0 o
C). By the time SST is 26˚F (-3.3
o
C) the HGBP valve will be passing the equivalent of
10 tons (35.2 kW) of R-407C refrigerant from the discharge line to the inlet of the evaporator.
Application Guide AG 31-011 39
Installation Details
Pump Down
Some air conditioning systems are designed with either recycling or a one-time pump down cycle.
These systems have a condenser sized large enough to hold the refrigerant charge. When cooling is no longer required, a solenoid valve in the liquid line closes. The compressor continues operating until the suction pressure drops below the suction pressure cutout switch. Once the suction pressure switch opens, the compressor stops. One-time pump down systems stay off until there is a need for cooling. Recycling pump down allows the compressor to restart if the suction pressure switch closes, even if cooling is unnecessary. The solenoid is still closed (no cooling required) so the compressor will quickly lower the suction pressure to where the pressure switch opens again. An example of this is the McQuay RPS C-vintage Applied Rooftop System.
The advantage of pump down is that most of the refrigerant in the evaporator is removed. Without pump down, during the off cycle, the refrigerant may migrate to the evaporator and/or suction line.
On start up, the liquid refrigerant may be drawn into the compressor and cause slugging. If the casing of the compressor is allowed to get colder than the rest of the circuit, refrigerant throughout the circuit may migrate to the compressor crankcase, condense and cause flooded starts.
Systems that do not have pump down may still have a solenoid that closes while the compressor is off to limit refrigerant migration. Crankcase heaters may also be added to help raise the compressor temperature and avoid refrigerant condensation.
When pump down is part of the equipment design, a solenoid valve will be required in the liquid
line as shown in Figure 16 (page 34). It should be installed as close to the evaporator as possible,
just before the TX valve. With pump down, the condenser must be able to hold the system charge.
Long field refrigerant piping arrangements may increase the refrigerant volume above the capacity of the condenser and limit service pump down. A receiver may be added to store the refrigerant.
Consult the manufacturer if a receiver is required.
Piping Insulation
Suction lines are cold – 40°F (4.4°C) SST – and cause condensation, even in conditioned spaces. In addition, any heat that enters the refrigerant adds to the superheat and reduces system efficiency.
For these reasons, suction lines should be insulated with a vapor proof insulation. This is a requirement of many building codes. Rubratex is the most common form of refrigerant line insulation.
Liquid lines generally are insulated. They are warm to hot (110°F (43.3°C) for air-cooled). If liquid lines pass through a space that is warmer than the refrigerant (i.e. the roof of a building at roof level), or if they could be considered hot enough to pose a safety risk, then insulation should be added.
Discharge lines are generally uninsulated. They may be very hot, in excess of 150°F (66°C), so insulation may be warranted as a safety consideration, or if the heat loss from the discharge gas line would be considered objectionable to the space.
Hot gas bypass lines should be insulated, especially if the runs are long or if the piping is exposed to cold temperatures.
40 Application Guide AG 31-011
Refrigerant Line Installation
Refrigerant lines need to be securely installed to minimize vibration that causes noise and damages piping. Reciprocating compressors, in particular, cause vibration. Steel braided flexible refrigerant lines (a must for spring isolated reciprocating compressors) minimize this vibration. Follow manufacturer’s instructions when using steel braided lines. Discharge mufflers are also occasionally used on discharge lines to minimize gas pulsations.
Refrigerant lines that rub against solid objects wear holes through copper and create a leak. For this reason, when refrigerant lines pass through walls, the line should pass through sleeved openings in such a manner that the lines do not touch.
There are several commercially available pipe clamping systems that allow pipes to be held rigid without causing damage to them. Most include some form of rubber grommet around the pipe, which is then secured within a bracket. Many building codes specify minimum support spacing.
Piping should also be protected from mechanical damage. Where piping is exposed to possible damage, the lines should be routed out of the way or be protected in some form of chase. Burying refrigerant lines should be avoided.
Application Guide AG 31-011 41
Low Ambient Operation
Refrigeration circuit components are sized for the most demanding application point. This is typically when the ambient temperature is high and the evaporator temperature is low. Many systems are required to operate properly when the ambient temperature is much lower. The issue here is the condenser becomes “too efficient” and lowers the liquid temperature and pressure beyond the range that the TX valve compensates for. In these applications, some form of low ambient control is required.
Water-cooled systems typically use some form of condenser water bypass line to maintain head pressure. For air-cooled systems, there are three common approaches to design for low ambient operation;
• Fan cycling
• Fan speed control
• Condenser flood back
Fan Cycling and Fan Speed Control
Fan cycling and fan speed control are the most common forms of low ambient operation for commercial air conditioning systems. Fan cycling entails staging condenser fans on and off based on the ambient temperature or the head pressure. Ambient-based control is cost-effective, but should only be used with air conditioning applications. Process loads must use pressure-based controls.
Fan speed control entails using some form of fan speed controller to modulate air-flow through the condenser. Fan speed is usually based on head pressure.
Both of these approaches are options provided by the equipment manufacturer and have minimal impact upon the piping system design, other than requiring a port for the head pressure sensor.
Condenser Flood Back Design
Figure 20 shows a typical condenser flood back arrangement. As the ambient temperature drops,
the head pressure drops. A head pressure control valve (refrigerant flow regulator) controlled by head pressure begins to close, restricting flow of liquid refrigerant from the condenser. Liquid refrigerant “floods” the condenser. As the tubes in the condenser flood, they reduce the surface area available for condensation and reduce the heat rejection capacity. As the condenser floods, the head pressure climbs until it reaches the setting of the head pressure control valve.
42 Application Guide AG 31-011
Figure 20 - Typical Condenser Flood Back Arrangement
Head Pressure
Control Valve
Condenser Coil
Receiver
Discharge Line
Liquid Line
Single head pressure control valve arrangements are available from several manufacturers. Refer to the manufacturers instructions for sizing and applications.
A receiver is required to store refrigerant during warmer weather. The receiver should be sized so it is at 80% of capacity while containing the entire system charge. Another aspect of receivers is that they contain both liquid and gaseous refrigerant at the same time. By their design, receivers prohibit liquid sub-cooling from occurring. Without liquid sub-cooling the capacity of the system is reduced and care must be taken in the design of the liquid line to avoid flashing at the TX valve.
Flooded systems are an excellent method of providing head pressure control in cold climates, but they increase initial cost, add complexity to the refrigeration system, increase installation time, and increase the refrigerant charge. The loss of sub-cooling should be recognized. If a flooded system is required, consult the manufacturer prior to installation.
☺Tip: Flooded systems with receivers are complex. Consult the manufacturer for assistance before installing.
Application Guide AG 31-011 43
Safety and the Environment
Refrigeration systems contain fluids under pressure at dangerous temperatures and pressures.
Proper safety procedures must be followed to provide a system that is acceptable. ASHRAE
Standard 15, Safety Code for Mechanical Refrigeration and ASME Standard B31.5, Refrigeration
Piping should be followed. Most building codes require adherence to these Standards.
Technicians should also be EPA or other government agency certified to handle refrigerants.
44 Application Guide AG 31-011
Appendix 1 - Glossary
Accumulator (suction) A device installed just before a compressor in the suction line that is used to separate vapor refrigerant from liquid refrigerant and oil. They are common in heat pumps and industrial refrigeration applications.
Adiabatic Process A process where energy gain to the surroundings is zero. Enthalpy remains constant for the fluid. An example is the refrigeration expansion process.
ASC (Auxiliary Side Connector) A fitting used in conjunction with a distributor to introduce hot gas refrigerant into the distributor for hot gas bypass.
Azeotropic Refrigerants Refrigerant blends that behave as a single substance. An example is R-
410A.
Carnot Cycle The ideal, reversible heat cycle between two infinite heat sinks.
Check Valve A valve that only allows flow in one direction. Used in refrigeration systems to stop refrigerant migration when the system is off.
Compressor A component in a refrigeration system that compresses refrigerant vapor to a higher pressure and temperature and consumes power to do so.
Condenser A component in a refrigeration system where refrigerant is condensed from a gas to a liquid and heat is rejected to the surroundings.
COP (Coefficient of Performance) The measure of the refrigeration system efficiency. Defined as refrigeration effect per compressor power.
Critical Point The point on a P-H Diagram where the saturated liquid and saturated vapor lines meet. Above the critical point, condensation cannot occur.
Density (d) The mass of a substance divided by the volume that substance occupies. It is measured in pounds per cubic foot (lb/ft³) or kilograms per meter cubed (kg/m³).
Desuperheater A device that removes super heat from either the suction or discharge gas line. This heat may be used in a heat recovery application such as hot water heating.
Direct Expansion (DX) Evaporator An evaporator where the refrigerant is in the tubes. Used for either refrigerant to air coils or chillers.
Discharge (hot gas) Line A refrigerant line that carries superheated, high pressure refrigerant from the compressor to the condenser.
Discharge muffler Used to reduce sound and pulsations in refrigerant lines. They are typically installed in discharge lines near the compressor.
Distributor A device that feeds two phase refrigerant evenly to each tube of a DX evaporator. It is usually part of the coil and is directly down stream of the TX valve.
Economizer (refrigerant) A form of two stage refrigeration cycle where the compressor has a port that allows refrigerant at an intermediate pressure to be injected into the compression process.
EER (Energy Efficiency Ratio) Refrigeration effect in British thermal units per hour per power input in watts (Btu/hr•W).
Enthalpy (h) The measure of energy content in a fluid. Measured in British thermal units per pound
(Btu/lb).
Entropy (s) The measure of molecular disorder of a substance. A process without change in entropy is considered ideal and reversible. Measured in British Thermal Units per pound –degree Rankin
(Btu/lb°R)
Application Guide AG 31-011 45
Evaporator A component in a refrigeration system where refrigerant is boiled from a liquid to gas and heat is absorbed from the surroundings. It is the component that performs the cooling effect.
Expansion Device A component that reduces the pressure and temperature adiabatically in a refrigeration system. There are several types but a thermal expansion (TX) valve is most common for air conditioning applications. The device is located in the liquid line as close to the evaporator as possible.
Filter-Drier A device used to filter refrigerant to remove contaminants. It also contains a desiccant that removes moisture from the refrigerant. Installed on liquid and/or suction lines.
Flashing Partial or total vaporization obtained by sudden reduction of pressure.
Flash Tank A component in a refrigeration system used to separate liquid refrigerant from vapor at an intermediate pressure. Commonly used in two stage refrigeration cycles.
Floodback A process where liquid refrigerant forms and moves to the lowest or coldest part of the refrigerant circuit. When unplanned for, floodback is detrimental to the operation of the refrigeration system.
Flooded Evaporator For chiller evaporators, the refrigerant is outside the tubes and all the tubes are submersed in liquid refrigerant.
Glide The change in volumetric composition and saturation temperature experienced by Zeotropic refrigerants during boiling.
Head Pressure Control Valve A pressure regulating valve that diverts flow around the condenser as the pressure drops. This is used as part of liquid flood back head pressure control system.
Hot Gas Bypass A method of maintaining suction pressure to the compressor during periods of light load by recirculating discharge gas from the leaving side of the compressor back to either the inlet of the evaporator or the suction line.
Hot Gas Reheat A method of reheating supply air after it has been cooled by using a second coil down stream of the evaporator and passing discharge gas from the compressor through it.
Intercooler A component in a refrigeration system used to desuperheat compressed refrigerant with cool liquid refrigerant. Commonly used in two stage refrigeration cycles to cool refrigeration from the booster compressor.
Isentropic Efficiency (ŋ
s
) Measure of compressor efficiency defined as Δh isnetropic
/ Δh actual
.
Isentropic Process A process where the entropy remains constant. Such a process is said to be reversible and cannot be more efficient. An example is isentropic compression (which cannot actually occur but is used as a benchmark to measure actual compressor performance against – See isentropic efficiency.)
Isobaric Process A process that occurs at constant pressure. An example is evaporation in the evaporator.
Isolators Components used to stop vibration and noise from passing beyond the source. There are isolators for compressors and refrigerant piping. Compressor isolators are rubber in shear (RIS) or spring. Refrigerant piping isolators are usually rubber grommets used with a clamping system.
Isothermal Process A process that occurs at constant temperature. An example is evaporation in the evaporator.
Liquid Floodback head pressure control A method of maintaining proper head pressure during low ambient operation by flooding the condenser with liquid refrigerant and reducing the effective heat transfer surface of the condenser.
Liquid Line A refrigerant line that moves liquid high pressure refrigerant from the condenser to an expansion device.
46 Application Guide AG 31-011
Liquid overfeed system An evaporator where the refrigerant is mechanically pumped faster than it is boiled so liquid refrigerant exits the evaporator. The mixture leaving the evaporator enters a low pressure receiver where the vapor is drawn off to the compressor and the liquid is returned to the evaporator. This arrangement is common in industrial applications.
Liquid Sub-cooling Reheat A method of reheating supply air after it has been cooled by using a second coil down stream of the evaporator and passing liquid refrigerant from the condenser through it.
Low Ambient Control A control process that maintains condenser pressure at an acceptable level during periods of low ambient temperature and/or load. Examples include, fan cycling, fan speed control, and liquid flood back control.
Mass (m) The quantity of a substance present. It is measured in pounds or lb m
or kilograms ( kg).
Oil Separator A vessel in a refrigeration circuit used to separate oil from refrigerant. They are usually in the discharge line. The oil is returned to the compressor sump.
Pressure (p) Force over unit area. Bursts pipes or expands balloons. It is measured in pounds per square inch (PSI) or Pascals (Pa).
Quality (χ) The ratio of vapor mass to liquid mass refrigerant during evaporation and/or condensation.
Receiver A container used to store liquid refrigerant. Typically used when the condenser cannot hold the refrigerant charge or for liquid flood back low ambient control.
Reversing Valve A device in a refrigeration circuit used to convert an air conditioner into a heat pump. When powered, the reversing valve will switch the evaporator and condenser to reverse the rejection of heat.
Riser A refrigerant pipe that runs vertically.
Rubatex A brand name for a moisture proof expanded rubber insulation commonly used on refrigerant piping for thermal insulation.
Saturation Condition A state where liquid and vapor refrigerant are in direct contact with each other and all properties remain unchanged overtime. When a refrigerant is in saturation condition there can be only one temperature for a given pressure and visa versa.
Saturated Condensing Temperature The saturation condition that exists in the condenser.
Saturated Suction Temperature The saturation condition that exists in the evaporator.
Service Valve A refrigerant valve that can be manually closed to isolate part of a refrigeration circuit for servicing.
Sight Glass A refrigerant piping fitting that has a window to allow viewing of the refrigerant. They are used in the liquid line as close to the TX valve as possible to visualize vapor bubbles. Some sight glasses include a moisture indicator used to mark the presences of moisture in the refrigeration system.
Solenoid Valve A two position valve (open with power, closed without power) commonly used in refrigerant piping systems to isolate a section of the refrigerant circuit. Also used in pump down and hot gas bypass arrangements.
Specific Heat (c p
) The energy needed to raise the temperature of a unit of mass one degree of temperature. Measured in Btu/lb m
°F or (kJ/(kg°C))
Sub-cooled Liquid A liquid that has been cooled below the saturation condition resulting in lower temperature and enthalpy. This is used to offset pressure losses in liquid lines that lead to flashing and to increase the capacity of the refrigeration circuit.
Suction Line A refrigerant line that carries low pressure refrigerant vapor from the evaporator to the compressor.
Application Guide AG 31-011 47
Superheated Vapor A vapor that has been heated beyond the saturation condition resulting in increased temperature and enthalpy. This is done to make sure the refrigerant in the suction line entering the compressor is truly a vapor.
Temperature (T) Represents the average motion of the molecules in the fluid. It is measured in °F
(Fahrenheit) (Celsius or °C).
Thermal Expansion (TX) Valve A pressure regulating valve used in refrigeration systems to lower the liquid refrigerant pressure from the condensing pressure to the evaporation pressure. Thermal expansion valves modulate refrigerant flow based on superheat in the suction line.
Trap A “P” shaped piping fitting that holds either liquid refrigerant or oil.
Venturi An alternative device to a distributor for feeding two phase refrigerant flow into each tube of a DX evaporator. It is usually part of the coil and is directly down stream of the TX valve.
Volume (V) The geometrical space occupied by a fluid. It is measured in cubic feet or ft³ (cubic meters or m³)
Volumetric Efficiency (ŋ
va
rate/ideal volume flow rate.
) Measure of compressor performance defined as actual volume flow
Zeotropic Refrigerants Refrigerant blends where the components do not behave asone substance.
Zeotropic refrigerants experience glide. An example is R-407C.
48 Application Guide AG 31-011
Appendix 2 – Refrigerant Piping Tables (Inch-Pound)
3 5/8
4 1/8
5 1/8
6 1/8
2 1/8
2 5/8
3 1/8
7/8
1 1/8
1 3/8
1 5/8
5/8
3/4
8 1/8
Table 3 - Copper Tube Data
Nominal
Dia.
Type
Wall
Dia.
Inside
D (in)
Outside
(ft²/ft)
Area
Inside
(ft²/ft)
Meta l
Area
(in²)
Flow
Area
(in²)
Weight
Tube
(lb/ft)
Working Pressure
ASTM B88 To
250°F
Annealed
(PSIG)
Draw n
(PSIG
)
0.131 894 1676
0.131 638 1197
0.164 715 1341
0.164 584 1094
0.196 596 1117
0.196 511 958
0.229 677 1270
0.229 469 879
0.295
0.295
527
405
988
760
0.360 431
0.360 365
0.425 404
808
684
758
0.425
0.556
0.556
0.687
0.687
0.818
0.818
337
356
300
330
278
318
263
0.949 302
0.949 252
1.080 296
1.080 243
1.342 285
1.342 222
1.603 286
1.603 208
2.127 304
2.127 224
566
472
555
456
534
417
536
391
570
421
631
668
573
619
521
596
492
6
ASHRAE Handbook HVAC Systems And Equipment, Chapter 41, 2004. © American Society of
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.
Application Guide AG 31-011 49
2 5/8
3 1/8
3 5/8
4 1/8
5 1/8
6 1/8
8 1/8
1/2
5/8
7/8
1 1/8
1 3/8
1 5/8
2 1/8
Table 4 - Equivalent Length for Fittings (feet)
Nominal
Dia.
90°
Std
90°
Long
Radius
Smooth Elbows
1.4 0.9
1.6 1.0
2.0 1.4
2.6 1.7
3.3 2.3
4.0 2.6
5.0 3.3
90°
Street
45°
Std
45°
Street
180°
Std
Tee
Branch
Flow
Smooth Bend Tee Connections
Straight Through Flow
No
Reduction
Reduced
25%
Reduced
50%
2.3 0.7 1.1 2.3 2.7 0.9
2.5 0.8 1.3 2.5 3.0 1.0
3.2 0.9 1.6 3.2 4.0 1.4
4.1 1.3 2.1 4.1 5.0 1.7
5.6 1.7 3.0 5.6 7.0 2.3
6.3 2.1 3.4 6.3 8.0 2.6
8.2 2.6 4.5 8.2 10.0 3.3
5.2 4.1
6.4 5.0
7.3 5.9
10.0 6.7 17.0 6.7
11.0 8.2
16.0 10.0 25.0 7.9 13.0 25.0 30.0 10.0
20.0 13.0 - 10.0 - 33.0 40.0 13.0
1.2 1.4
1.4 1.6
1.9 2.0
2.2 2.6
3.1 3.3
3.7 4.0
4.7 5.0
5.6
7.0
8.0
9.0
6.0
7.5
9.0
10.0
12.0 13.0
14.0 16.0
18.0 20.0
Table 5 - Equivalent Length For Valves And Refrigeration Devices (feet)
Nominal
Diameter
Globe Or
Solenoid
60°
Wye
Valve
45°
Wye
Valve
Angle
Valve
Gate
Valve
Swing
Check
Sight
Glass
Filter
Drier
3 1/8
3 5/8
4 1/8
5 1/8
6 1/8
8 1/8
1/2
5/8
7/8
1 1/8
1 3/8
1 5/8
2 1/8
2 5/8
Suction
Filter
17 8 6 6 0.6 5 1.0 12 15
18 9 7 7 0.7 6 1.2 15 17
22 11 9 9 0.9 8 1.6 21 22
29 15 12 12 1.0 10 2.0 26 25
38 20 15 15 1.5 14 2.5 35 36
43 24 18 18 1.8 16 2.6 - 40
55 30 24 24 2.3 20
69 35 29 29 2.8 25
84 43 35 35 3.2 30
100 50 41 41 4.0 35
120 58 47 47 4.5 40
140 71 58 58 6.0 50
170 88 70 70 7.0 60
220 115
7
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
8
Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org
.
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org
.
50 Application Guide AG 31-011
Table 6 - R-22 Refrigerant Line Sizing Table (tons)
1/2
5/8
7/8
1 1/8
1 3/8
1 5/8
2 1/8
2 5/8
3 1/8
3 5/8
4 1/8
Suction Discharge
SST 0 o
F 20 o
F 40 o
F 0 o
F 20 o
F 40 o
F
ΔT 2
Δp
(PSI)
OD
(in) o
F 1 o
F 0.5
o
F 2 o
F 1 o
F 0.5
o
F 2 o
F 1 o
F 0.5
o
F 1 o
F 1 o
F 1 o vel =
1.60 0.813 0.406 2.22 1.104 0.552 2.91 1.455 0.727 3.05 3.05 3.05
100fpm o
F
3.05
- 0.18 0.12 0.40 0.27 0.19 0.6 0.40 0.27 0.8 0.8 0.8 2.3 3.6
0.51 0.34 0.23 0.76 0.52 0.35 1.1 0.75 0.51 1.5 1.6 1.6 3.7 6.7
1.3 0.91 0.62 2.0 1.37 0.93 2.9 1.97 1.35 4.0 4.1 4.2 7.8 18.2
2.7 1.86 1.27 4.0 2.77 1.90 5.8 3.99 2.74 8.0 8.3 8.5 13.2 37.0
4.7 3.25 2.22 7.0 4.84 3.32 10.1 6.96 4.78 14.0 14.4 14.8 20.2 64.7
7.5 5.16 3.53 11.1 7.67 5.26 16.0 11.00 7.57 22.1 22.7 23.4 28.5 102.5
15.6 10.71 7.35 23.1 15.92 10.96 33.1 22.81 15.73 45.7 47.1 48.5 49.6 213.0
27.5 18.97 13.04 40.8 28.19 19.40 58.3 40.38 27.84 80.4 82.9 85.4 76.5 376.9
44.0 30.31 20.85 65.0 44.93 31.00 92.9 64.30 44.44 128.2 132.2 136.2 109.2 601.5
65.4 45.09 31.03 96.6 66.81 46.11 137.8 95.68 66.09 190.3 196.2 202.1 147.8 895.7
92.2 63.71 43.85 136.3 94.25 65.12 194.3 134.81 93.22 267.8 276.1 284.4 192.1 1263.2
Values in Table 6 are based on 105°F condensing temperature. Multiply table capacities by the following factors for other condensing temperatures.
Condensing Temperature (°F)
80
90
100
110
120
130
140
Suction Line Discharge Line
1.11 0.79
1.07 0.88
1.03 0.95
0.97 1.04
0.90 1.10
0.86 1.18
0.80 1.26
Notes for Table 6:
1. Table capacities are in tons of refrigeration.
2. Δp = pressure drop due to line friction, psi per 100 ft of equivalent line length
3. Δt = corresponding change in saturation temperature, °F per 100 ft
4. Line capacity for other saturation temperatures Δt and equivalent lengths L e
Line Capacity
=
Table Capacity
⎛
⎜⎜
Table
Acutal
L e
L e
×
Actual
Δ
t
Table
Δ
t
⎞
⎟⎟
0 .
55 e
Δ
t
=
Table
Δ
t
⎛
⎜⎜
Actual L e
Table L e
⎞
⎟⎟
⎛
⎜⎜
Actual Capacity
Table Capacity
⎞
⎟⎟
1 .
8
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ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
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.
Application Guide AG 31-011 51
Table 7 - R-134a Refrigerant Line Size Table (tons)
2 5/8
3 1/8
3 5/8
4 1/8
5 1/8
6 1/8
1/2
5/8
7/8
1 1/8
1 3/8
1 5/8
2 1/8
Suction
SST 0 o
F 20 o
F 40 o
F 0 o
F 20 o
F 40 o
F
ΔT 2
Δp
(PSI) o
F 1 o
F 0.5
o
F 2 o
F 1 o
F 0.5
o
F 2 o
F 1 o
F 0.5
o
F 1 o
F 1 o
F 1 o vel = o
F
1.00 0.50 0.25 1.41 0.71 0.35 1.93 0.97 0.48 2.20 2.20 2.20
100fpm
2.20
OD
(in)
0.14 0.10 0.07 0.23 0.16 0.11 0.35 0.24 0.16 0.5 0.6 0.6 2.13 2.79
0.27 0.18 0.12 0.43 0.29 0.20 0.66 0.45 0.31 1.0 1.1 1.1 3.42 5.27
0.71 0.48 0.33 1.14 0.78 0.53 1.75 1.20 0.82 2.7 2.8 2.9 7.09 14
1.45 0.99 0.67 2.32 1.59 1.08 3.54 2.43 1.66 5.4 5.7 6.0 12.1 28.4
2.53 1.73 1.18 4.04 2.77 1.89 6.17 4.25 2.91 9.4 9.9 10.4 18.4 50
4.02 2.75 1.88 6.39 4.40 3.01 9.77 6.72 4.61 14.9 15.7 16.4 26.1 78.6
8.34 5.73 3.92 13.3 9.14 6.27 20.20 14.0 9.59 30.8 32.4 34.0 45.3 163
14.80 10.2 6.97 23.5 16.2 11.1 35.80 24.7 17.0 54.4 57.2 59.9 69.9 290
23.70 16.2 11.1 37.5 25.9 17.8 57.10 39.4 27.2 86.7 91.2 95.5 100 462
35.10 24.2 16.6 55.8 38.5 26.5 84.80 58.7 40.4 129.0 135. 142.0 135 688
49.60 34.2 23.5 78.7 54.3 37.4 119.4 82.6 57.1 181.0 191. 200.0 175 971
88.90 61.3 42.2 141.0 97.2 67.1 213.0 148. 102. 323.0 340. 356.0 -
143.0 98.8 68.0 226.0 157. 108. 342.0 237. 165. 518.0 545. 571.0 -
-
-
Values in Table 7 are based on 105°F condensing temperature. Multiply table capacities by the following factors for other condensing temperatures.
Condensing Temperature (°F)
80
90
100
110
120
130
Suction Line Discharge Line
1.158 0.804
1.095 0.882
1.032 0.961
0.968 1.026
0.902 1.078
0.834 1.156
Notes for Table 7:
1. Table capacities are in tons of refrigeration.
2. Δp = pressure drop due to line friction, psi per 100 ft of equivalent line length
3. Δt = corresponding change in saturation temperature, °F per 100 ft
4. Line capacity for other saturation temperatures Δt and equivalent lengths L e
Line Capacity
=
Table Capacity
⎛
⎜⎜
Table
Acutal
L e
L e
×
Actual
Δ
t
Table
Δ
t
⎞
⎟⎟
0 .
55
Δt for other capacities and equivalent lengths L e
Δ
t
=
Table
Δ
t
⎛
⎜⎜
Actual L e
Table L e
⎞
⎟⎟
⎛
⎜⎜
Actual Capacity
Table Capacity
⎞
⎟⎟
1 .
8
10
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org
.
52 Application Guide AG 31-011
Table 8 - R-410A Refrigerant Line Size Table (tons)
Suction
SST 0 o
F 20 o
F 40 o
F 0 o
F 20 o
F 40 o
F
ΔT 2
Δp
(PSI) o
F 1 o
F 0.5
o
F 2 o
F 1 o
F 0.5
o
F 2 o
F 1 o
F 0.5
o
F 1 o
F 1 o
F 1 o vel =
2.57 1.29 0.64 3.46 1.73 0.87 4.50 2.25 1.13 4.75 4.75 4.75
100fpm
OD
(in) o
F 5 o
F
4.75 23.30
1/2
5/8
7/8
1 1/8
0.4 0.3 0.2 0.6 0.4 0.3 0.9 0.6 0.4 1.3 1.3 1.3 2.0 4.6 10.8
0.8 0.5 0.4 1.2 0.8 0.6 1.7 1.2 0.8 2.4 2.4 2.5 3.2 8.6 20.2
2.1 1.4 1.0 3.1 2.1 1.5 4.4 3.0 2.1 6.2 6.4 6.5 6.7 22.6 52.9
1 3/8
1 5/8
2 1/8
2 5/8
3 1/8
11.6 8.0 5.5 17.1 11.8 8.2 24.3 16.7 11.6 34.3 35.3 36.1 24.6 125.9 291.5
24.1 16.6 11.4 35.5 24.5 16.9 50.2 34.8 24.1 70.8 72.8 74.6 42.8 260.7 601.1
42.5 29.4 20.2 62.5 43.3 30.0 88.4 61.4 42.5 124.5 128.3 131.2
67.8 46.8 32.4 99.5 69.1 47.8 140.8 97.9 67.9 198.4 204.3 209.0
66.0
94.2
459.7 1056.4
733.0 1680.5
3 5/8
100.5 69.7 48.1 147.7 102.7 71.0 208.7 145.3 100.8 293.9 302.7 309.6 127.4 1087.5 2491.0
4 1/8
141.6 98.3 67.9 208.2 144.7 100.2 293.7 204.8 142.1 413.8 426.1 435.9 165.7 1530.2 3500.9
5 1/8
253.1 175.4 121.5 370.8 258.0 179.2 523.2 365.0 253.8 737.3 759.3 776.7 258.2 2729.8 6228.4
6 1/8
405.8 282.3 195.7 594.9 414.5 287.8 839.8 586.1 407.6 1180.9 1216.2 1244.1 371.1 4383.7
Values in Table 8 are based on 105°F condensing temperature. Multiply table capacities by the following factors for other condensing temperatures.
Condensing Temperature (°F)
80
90
100
110
120
130
Suction Line Discharge Line
1.170 0.815
1.104 0.889
1.035 0.963
0.964 1.032
0.889 1.096
0.808 1.160
Notes for Table 8:
1. Table capacities are in tons of refrigeration.
2. Δp = pressure drop due to line friction, psi per 100 ft of equivalent line length
3. Δt = corresponding change in saturation temperature, °F per 100 ft
4. Line capacity for other saturation temperatures Δt and equivalent lengths L e
Line Capacity
=
Table Capacity
⎛
⎜⎜
Table
Acutal
L e
L e
×
Actual
Δ
t
Table
Δ
t
⎞
⎟⎟
0 .
55 e
Δ
t
=
Table
Δ
t
⎛
⎜⎜
Actual L e
Table L e
⎞
⎟⎟
⎛
⎜⎜
Actual Capacity
Table Capacity
⎞
⎟⎟
1 .
8
11
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
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.
Application Guide AG 31-011 53
Table 9 - R-407C Refrigerant Line Size Table
Suction
SST 0 o
F 20 o
F 40 o
F 0 o
F 20 o
F 40 o
F
ΔT 2
Δp
(PSI) o
F 1 o
F 0.5
o
F 2 o
F 1 o
F 0.5
o
F 2 o
F 1 o
F 0.5
o
F 1 o
F 1 o
F 1 o
1.55 0.78 0.39 2.16 1.08 0.54 2.92 1.46 0.73 3.30 3.30 3.30 vel =
100fpm o
F 5 o
F
3.30 16.90
OD
(in)
1/2
5/8
7/8
1 1/8
1 3/8
0.2 0.2 0.1 0.4 0.3 0.2 0.5 0.4 0.3 0.8 0.9 0.9 2.1 3.8 8.9
0.4 0.3 0.2 0.7 0.5 0.3 1.0 0.7 0.5 1.5 1.6 1.7 3.4 7.1 16.7
1.2 0.8 0.5 1.8 1.2 0.8 2.7 1.8 1.3 4.1 4.2 4.4 6.9 18.7 43.7
2.3 1.6 1.1 3.6 2.5 1.7 5.4 3.7 2.6 8.2 8.5 8.9 11.8 37.9 88.2
4.1 2.8 1.9 6.3 4.4 3.0 9.5 6.5 4.5 14.2 14.8 15.4 18.0 66.2 153.5
1 5/8
2 1/8
2 5/8
6.4 4.4 3.0 10.0 6.9 4.7 14.9 10.3 7.1 22.5 23.4 24.3 25.5 104.7 241.9
13.4 9.2 6.3 20.7 14.3 9.8 30.9 21.4 14.7 46.5 48.4 50.3 44.4 217.1 499.2
23.6 16.3 11.2 36.6 25.3 17.4 54.5 37.8 26.1 82.0 85.4 88.7 68.5 383.7 879.9
3 1/8
3 5/8
37.8 26.1 17.9 58.3 40.3 27.8 86.9 60.2 41.6 130.5 136.0 141.2 97.7 611.3 1401.5
56.2 38.8 26.7 86.6 60.0 41.4 128.9 89.5 61.8 193.3 201.4 209.2 132.0 907.9 2076.6
4 1/8
79.2 54.7 37.7 122.1 84.6 58.5 181.3 126.1 87.3 272.6 284.0 295.0 171.8 1281.5 2923.4
5 1/8
141.6 97.9 67.6 218.1 151.2 104.7 323.5 225.1 156.1 485.5 505.8 525.3 267.8 2288.8 5209.1
6 1/8
227.9 157.6 109.0 350.4 243.2 168.4 519.6 361.7 251.1 779.0 811.6 843.0 385.0 3676.9 8344.1
Values in Table 9 are based on 105°F condensing temperature. Multiply table capacities by the following factors for other condensing temperatures.
Condensing Temperature (°F)
80
90
100
110
120
130
Suction Line Discharge Line
1.163 0.787
1.099 0.872
1.033 0.957
0.966 1.036
0.896 1.109
0.824 1.182
Notes for Table 9:
1. Table capacities are in tons of refrigeration.
2. Δp = pressure drop due to line friction, psi per 100 ft of equivalent line length
3. Δt = corresponding change in saturation temperature, °F per 100 ft
4. Line capacity for other saturation temperatures Δt and equivalent lengths L e
Line Capacity
=
Table Capacity
⎛
⎜⎜
Table
Acutal
L e
L e
×
Actual
Δ
t
Table
Δ
t
⎞
⎟⎟
0 .
55
Δt for other capacities and equivalent lengths L e
Δ
t
=
Table
Δ
t
⎛
⎜⎜
Actual L e
Table L e
⎞
⎟⎟
⎛
⎜⎜
Actual Capacity
Table Capacity
⎞
⎟⎟
1 .
8
12
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org
.
54 Application Guide AG 31-011
20
0
40
-40
-20
Table 10 - R-22 Minimum Capacity For Suction Riser (tons)
Saturated
Suction
Temp
Suction
Gas Temp
Pipe O.D.
(inches)
(°F) (°F)
1/8 1 5/8 2 1/8
Area (in
2
)
2 5/8 3 1/8 3 5/8 4 1/8
0.146 0.233 0.348 0.484 0.825 1.256 1.780 3.094 4.770 6.812 9.213 11.970
-30
-10
10
-10
10
0.067 0.119 0.197 0.298 0.580 0.981 1.52 3.03 5.20 8.12 11.8 16.4
0.065 0.117 0.194 0.292 0.570 0.963 1.49 2.97 5.11 7.97 11.6 16.1
0.066 0.118 0.195 0.295 0.575 0.972 1.50 3.00 5.15 8.04 11.7 16.3
0.087 0.156 0.258 0.389 0.758 1.28 1.98 3.96 6.80 10.6 15.5 21.5
0.085 0.153 0.253 0.362 0.744 1.26 1.95 3.88 6.67 10.4 15.2 21.1
30
10
0.086 0.154 0.254 0.383 0.747 1.26 1.95 3.90 6.69 10.4 15.2 21.1
0.111 0.199 0.328 0.496 0.986 1.63 2.53 5.04 8.66 13.5 19.7 27.4
30 0.108 0.194 0.320 0.484 0.842 1.59 2.46 4.92 8.45 13.2 19.2 26.7
50
30
50
70
50
70
90
0.109 0.195 0.322 0.486 0.946 1.60 2.47 4.94 8.48 13.2 19.3 26.8
0.136 0.244 0.403 0.608 1.18 2.00 3.10 6.18 10.6 16.6 24.2 33.5
0.135 0.242 0.399 0.603 1.17 1.99 3.07 6.13 10.5 16.4 24.0 33.3
0.135 0.242 0.400 0.605 1.18 1.99 3.08 6.15 10.6 16.5 24.0 33.3
0.167 0.300 0.495 0.748 1.46 2.46 3.81 7.6 13.1 20.4 29.7 41.3
0.165 0.296 0.488 0.737 1.44 2.43 3.75 7.49 12.9 20.1 29.3 40.7
0.165 0.296 0.488 0.738 1.44 2.43 3.76 7.50 12.9 20.1 29.3 40.7
Refrigeration capacity in tons is based on 90°F liquid temperature and superheat as indicated by the listed temperature. Multiply table capacities by the following factors for other liquid line temperatures.
Liquid Temperature (°F)
50 60 70 80 100 110 120 130 140
1.17 1.14 1.10 1.06 0.98 0.94 0.89 0.85 0.80
13
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
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.
Application Guide AG 31-011 55
20
0
40
-40
-20
Table 11 - R-134a Minimum Capacity For Suction Riser (tons)
Saturated
Suction
Temp
Suction
Gas Temp
Pipe O.D.
(inches)
(°F) (°F)
1/8 1 5/8 2 1/8
Area (in
2
)
2 5/8 3 1/8 3 5/8 4 1/8
0.146 0.233 0.348 0.484 0.825 1.256 1.780 3.094 4.770 6.812 9.213 11.970
-30
-10
10
-10
10
30
10
30
50
30
50
70
50
70
90
0.089 0.161 0.259 0.400 0.78 1.32 2.03 4.06 7.0 10.9 15.9 22.1
0.075 0.135 0.218 0.336 0.66 1.11 1.71 3.24 5.9 9.2 13.4 18.5
0.072 0.130 0.209 0.323 0.63 1.07 1.64 3.28 5.6 8.8 12.8 17.8
0.101 0.182 0.294 0.453 0.88 1.49 2.31 4.61 7.9 12.4 18.0 25.0
0.084 0.152 0.246 0.379 0.74 1.25 1.93 3.86 6.6 10.3 15.1 20.9
0.081 0.147 0.237 0.366 0.71 1.21 1.87 3.73 6.4 10.0 14.6 20.2
0.113 0.205 0.331 0.510 0.99 1.68 2.6 5.19 8.9 13.9 20.3 28.2
0.095 0.172 0.277 0.427 0.83 1.41 2.17 4.34 7.5 11.6 17.0 23.6
0.092 0.166 0.268 0.413 0.81 1.36 2.1 4.20 7.2 11.3 16.4 22.8
0.115 0.207 0.335 0.517 1.01 1.7 2.63 5.25 9.0 14.1 20.5 28.5
0.107 0.193 0.311 0.480 0.94 1.58 2.44 4.88 8.4 13.1 19.1 26.5
0.103 0.187 0.301 0.465 0.91 1.53 2.37 4.72 8.1 12.7 18.5 25.6
0.128 0.232 0.374 0.577 1.12 1.9 2.94 5.87 10.1 15.7 22.9 31.8
0.117 0.212 0.342 0.528 1.03 1.74 2.69 5.37 9.2 14.4 21.0 29.1
0.114 0.206 0.332 0.512 1.00 1.69 2.61 5.21 8.9 14.0 20.4 28.3
Refrigeration capacity in tons is based on 90°F liquid temperature and superheat as indicated by the listed temperature. Multiply table capacities by the following factors for other liquid line temperatures.
Liquid Temperature (°F)
50 60 70 80 100 110 120 130 140
1.26 1.20 1.13 1.07 0.94 0.87 0.80 0.74 0.67
Table 12 - R-410A Minimum Capacity For Suction Riser (tons)
Saturated
Suction
Temp
Suction
Gas
Temp
Pipe O.D.
(inches)
(°F) (°F)
1/8 1 5/8
Area (in
2
)
2 1/8 2 5/8 3 1/8 3 5/8 4 1/8
0.146 0.233 0.348 0.484 0.83 1.26 1.78 3.094 4.770 6.812 9.213 11.97
0
20
40
10 0.167 0.317 0.542 0.833 1.67 2.92 4.58 9.58 17.17 26.67 40.00 55.83
10 0.192 0.363 0.667 0.958 1.96 3.42 5.33 11.08 19.58 30.83 45.83 64.17
10 0.213 0.400 0.683 1.067 2.17 3.75 6.00 12.42 21.67 35.00 51.67 71.67
Refrigeration capacity in tons is based on 90°F liquid temperature and superheat as indicated by the listed temperature. Multiply table capacities by the following factors for other liquid line temperatures. (Table data based on line size pressure drop formula shown on page 2.17 of ASHRAE Handbook Refrigeration 2006.)
Liquid Temperature (°F)
80 90 100 110 120 130 140
1.05 1.00 0.94 0.90 0.83 0.77 0.72
14
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org
.
56 Application Guide AG 31-011
Table 13 - R-407C Minimum Capacity For Suction Riser (tons)
Saturated
Suction
Temp
Suction
Gas
Temp
Pipe O.D.
(inches)
(°F) (°F)
1/8 1 5/8
Area (in
2
)
2 1/8 2 5/8 3 1/8 3 5/8 4 1/8
0.146 0.233 0.348 0.484 0.83 1.26 1.78 3.094 4.770 6.812 9.213 11.97
0
20
40
10 0.127 0.242 0.413 0.642 1.31 2.29 3.58 7.42 13.08 20.83 30.83 43.33
10 0.150 0.283 0.483 0.758 1.54 2.67 4.25 8.75 15.42 24.58 36.67 50.83
10 0.171 0.325 0.550 0.867 1.75 3.08 4.83 10.00 17.50 27.83 41.67 58.33
Refrigeration capacity in tons is based on 90°F liquid temperature and superheat as indicated by the listed temperature. Multiply table capacities by the following factors for other liquid line temperatures. (Table data based on line size pressure drop formula shown on page 2.17 of ASHRAE Handbook Refrigeration 2006.)
Liquid Temperature (°F)
80 90 100 110 120 130 140
1.05 1.00 0.95 0.90 0.85 0.80 0.74
Saturated
Temp
Table 14 - R-22 Minimum Capacity For Discharge Riser (tons)
Discharge
Gas Temp
Pipe O.D. (in)
(°F) (°F)
1/8 1 5/8 2 1/8
Area (in
2
)
2 5/8 3 1/8 3 5/8 4 1/8
0.146 0.233 0.348 0.484 0.825 1.256 1.780 3.094 4.770 6.812 9.213 11.970
90
100
80
110
120
110
140
170
120
150
180
130
160
190
140
170
200
150
0.235 0.421 0.695 1.050 2.03 3.46 5.35 10.70 18.3 26.8 41.8 57.9
0.223 0.399 0.659 0.996 1.94 3.28 5.05 10.10 17.4 27.1 39.6 54.9
0.215 0.385 0.635 0.960 1.87 3.16 4.89 9.76 16.8 26.2 38.2 52.9
0.242 0.433 0.716 1.060 2.11 3.56 5.50 11.00 18.9 29.5 43.0 69.6
0.226 0.406 0.671 1.010 1.97 3.34 5.16 10.30 17.7 27.6 40.3 55.9
0.216 0.387 0.540 0.956 1.88 3.18 4.92 9.82 16.9 26.3 38.4 53.3
0.247 0.442 0.730 1.100 2.15 3.83 5.62 11.20 19.3 30.1 43.9 60.8
0.231 0.414 0.884 1.030 2.01 3.40 5.26 10.50 18.0 28.2 41.1 57.0
0.220 0.394 0.650 0.982 1.91 3.24 3.00 9.96 17.2 26.8 39.1 54.2
0.251 0.451 0.744 1.120 2.19 3.70 5.73 11.40 19.6 30.6 44.7 62.0
0.235 0.421 0.693 1.050 2.05 3.46 3.35 10.70 18.3 28.6 41.8 57.9
0.222 0.399 0.658 0.994 1.94 3.28 5.06 10.10 17.4 27.1 39.5 54.8
0.257 0.460 0.760 1.150 2.24 3.78 5.85 11.70 20.0 31.3 45.7 63.3
180 0.239 0.428 0.707 1.070 2.08 3.51 5.44 10.80 18.6 29.1 42.4 58.9
210 0.225 0.404 0.666 1.010 1.96 3.31 5.12 10.20 17.6 27.4 40.0 55.5
Refrigeration capacity in tons based on saturated suction temperature of 20 o
F with 15 o saturated condensing temperature with 15 o
F superheat at indicated
F sub-cooling. For other saturated suction temperatures with 15 o
F superheat, use correction factors in the following table.
Saturated Suction Temperature (°F)
-40 -20 0 +40
0.92 0.95 0.97 1.02
15
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org
.
Application Guide AG 31-011 57
Saturated
Temp
Table 15 - R-134a Minimum Capacity For Discharge Riser (tons)
Discharge
Gas Temp
Pipe O.D. (in)
(°F) (°F)
1/8 1 5/8 2 1/8
Area (in
2
)
2 5/8 3 1/8 3 5/8 4 1/8
0.146 0.233 0.348 0.484 0.825 1.256 1.780 3.094 4.770 6.812 9.213 11.970
80
90
100
110
120
110 0.199 0.36 0.581 0.897 1.75 2.96 4.56 9.12 15.7 24.4 35.7 49.5
140 0.183 0.311 0.535 0.825 1.61 2.72 4.20 8.39 14.4 22.5 32.8 45.6
170 0.176 0.318 0.512 0.791 1.54 2.61 4.02 8.04 13.8 21.6 31.4 43.6
120
150
0.201 0.364 0.587 0.906 1.76 2.99 4.61 9.21 15.8 24.7 36.0 50.0
0.184 0.333 0.538 0.830 1.62 2.74 4.22 8.44 14.5 22.6 33.0 45.8
180 0.177 0.32 0.516 0.796 1.55 2.62 4.05 8.09 13.9 21.7 31.6 43.9
130 0.206 0.72 0.600 0.926 1.8 3.05 4.71 9.42 16.2 25.2 36.8 51.1
160 0.188 0.34 0.549 0.848 1.65 2.79 4.31 8.62 14.8 23.1 33.7 46.8
190 0.180 0.326 0.526 0.811 1.58 2.67 4.13 8.25 14.2 22.1 32.2 44.8
140 0.209 0.378 0.610 0.942 1.83 3.10 4.79 9.57 16.5 25.7 37.4 52.0
170
200
150
180
0.191 0.346 0.558 0.861 1.68 2.84 4.38 8.76 15.0 23.5 34.2 47.5
0.183 0.331 0.534 0.824 1.61 2.72 4.19 8.38 14.4 22.5 32.8 45.5
0.212 0.383 0.618 0.953 1.86 3.14 4.85 9.69 16.7 26 37.9 52.6
0.194 0.351 0.566 0.873 1.7 2.88 4.44 8.88 15.3 23.8 34.7 48.2
210 0.184 0.334 0.538 0.830 1.62 2.74 4.23 8.44 14.5 22.6 33.0 45.8
Refrigeration capacity in tons based on saturated suction temperature of 20 o
F with 15 o saturated condensing temperature with 15 o
F superheat at indicated
F sub-cooling. For other saturated suction temperatures with 15 o
F superheat, use correction factors in the following table.
Saturated Suction Temperature (°F)
-40 -20 0 +40
Sat.
Suction
Temp
Table 16 – R-410A Minimum Capacity For Discharge Riser (tons)
Discharge
Temp
Pipe O.D.
(inches)
(°F) (°F)
1/8 1 5/8
Area (in
2
)
2 1/8 2 5/8 3 1/8 3 5/8 4 1/8
0.146 0.233 0.348 0.484 0.83 1.26 1.78 3.094 4.770 6.812 9.213 11.97
80
100
140
160
0.33 0.610 1.060 1.590 3.19 5.54 8.75 13.80 24.40 38.90 57.80 81.70
0.34 0.628 1.092 1.638 3.29 5.71 9.01 14.21 25.13 40.07 59.53 84.15
120 180 0.35 0.647 1.125 1.687 3.38 5.88 9.28 14.64 25.89 41.27 61.32 86.68
Refrigeration capacity in tons based on saturated suction temperature of 40 saturated condensing temperature with 15 o o
F with 15 o
F superheat at indicated
F sub-cooling. For other saturated suction temperatures with 15 o
F superheat, use correction factors in the following table. (Table data based on line size pressure drop formula shown on page 2.17 of ASHRAE Handbook Refrigeration 2006.)
Saturated Suction Temperature (°F)
0.90 0.94 1.00 1.06
16
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org
.
58 Application Guide AG 31-011
Table 17 - R-407C Minimum Capacity For Discharge Riser (tons)
Sat.
Suction
Temp
Discharge
Temp
Pipe O.D.
(inches)
1/2 5/8 3/4 7/8 1 3/8 1 5/8
(°F) (°F)
Area (in
2
)
2 1/8 2 5/8 3 1/8 3 5/8 4 1/8
0.146 0.233 0.348 0.484 0.83 1.26 1.78 3.094 4.770 6.812 9.213 11.97
80 140 0.29 0.530 0.913 1.390 2.79 4.85 7.67 12.10 21.30 33.99 50.70 71.40
100 160 0.30 0.546 0.940 1.432 2.87 5.00 7.90 12.46 21.94 35.01 52.22 73.54
120 180 0.31 0.562 0.969 1.475 2.96 5.15 8.14 12.84 22.60 36.06 53.79 75.75
Refrigeration capacity in tons based on saturated suction temperature of 40 o
F with 30 o saturated condensing temperature with 10 o
F superheat at indicated
F sub-cooling. For other saturated suction temperatures with 30 o
F superheat, use correction factors in the following table. (Table data based on line size pressure drop formula shown on page 2.17 of ASHRAE Handbook Refrigeration 2006.)
Saturated Suction Temperature (°F)
0.96 0.98 1.00 1.02
Application Guide AG 31-011 59
Table 18 - R-22 Refrigerant Charge (lbs. Per 100 Feet of Pipe)
Line Size Flow Suction Line Liquid Line Discharge Line
OD Area inches in
2
2 5/8
3 1/8
3 5/8
4 1/8
5 1/8
6 1/8
8 1/8
1/2
5/8
7/8
1 1/8
1 3/8
1 5/8
2 1/8
40 o
F 105 o
F 140 o
F
68.72 lb./ft
3
0.145 0.15 6.92 0.70
0.233 0.25 11.12 1.13
0.484 0.51 23.10 2.34
0.825 0.87 39.37 3.99
1.257 1.33 59.99 6.08
1.779 1.88 84.90 8.61
3.905 4.13 186.36 18.90
4.772 5.04 227.73 23.09
6.812 7.20 325.08 32.97
9.213 9.74 439.66 44.58
11.977 12.66 571.57 57.96
18.665 19.72 890.74 90.33
26.832 28.35 1280.48 129.85
46.869 49.53 2236.69 226.81
Refrigerant weight per 100 feet of pipe is based on 105°F condensing temperature and 10°F sub-cooling, 140°F discharge temperature, and 40°F saturated suction temperature.
Table 19 - R-134a Refrigerant Charge (lbs. Per 100 Feet of Pipe)
Line Size Flow Suction Line Liquid Line Discharge Line
OD Area inches in
2
2 5/8
3 1/8
3 5/8
4 1/8
5 1/8
6 1/8
8 1/8
1/2
5/8
7/8
1 1/8
1 3/8
1 5/8
2 1/8
40 o
F 105 o
F 140 o
F
69.93 lb./ft
3
0.145 0.11 7.04 0.55
0.233 0.17 11.32 0.88
0.484 0.35 23.50 1.83
0.825 0.60 40.06 3.13
1.257 0.92 61.04 4.76
1.779 1.30 86.39 6.74
3.905 2.85 189.64 14.79
4.772 3.48 231.74 18.08
6.812 4.96 330.81 25.81
9.213 6.71 447.41 34.90
11.977 8.73 581.63 45.38
18.665 13.60 906.42 70.71
26.832 19.56 1303.03 101.65
46.869 34.16 2276.08 177.57
Refrigerant weight per 100 feet of pipe is based on 105°F condensing temperature and 10°F sub-cooling, 140°F discharge temperature, and 40°F saturated suction temperature.
60 Application Guide AG 31-011
Table 20 - R-410A Refrigerant Charge (lbs. Per 100 Feet of Pipe)
Line Size Flow Suction Line Liquid Line Discharge Line
OD Area
40 o
F 105 o
F 140 o
F
2 5/8
3 1/8
3 5/8
4 1/8
5 1/8
6 1/8
8 1/8
1/2
5/8
7/8
1 1/8
1 3/8
1 5/8
2 1/8
inches in
2
0.145 0.22 5.88
0.233 0.36 9.44
1.27
2.03
0.484 0.74 19.62 4.22
0.825 1.26 33.44 7.20
1.257 1.93 50.95 10.97
1.779 2.72 72.11 15.53
3.905 5.98 158.29 34.09
4.772 7.31 193.43 41.66
6.812 10.43 276.12 59.46
9.213 14.11 373.45 80.42
11.977 18.34 485.48 104.55
18.665 28.59 756.58 162.93
26.832 41.10 1087.63 234.22
46.869 71.79 1899.82 409.12
Refrigerant weight per 100 feet of pipe is based on 105°F condensing temperature and 10°F sub-cooling, 140°F discharge temperature, and 40°F saturated suction temperature.
Table 21 - R-407C Refrigerant Charge (lbs. Per 100 Feet of Pipe)
Line Size Flow Suction Line Liquid Line Discharge Line
OD Area
40 o
F 105 o
F 140 o
F
2 5/8
3 1/8
3 5/8
4 1/8
5 1/8
6 1/8
8 1/8
1/2
5/8
7/8
1 1/8
1 3/8
1 5/8
2 1/8
inches in
2
0.145 0.17 6.51 0.87
0.233 0.27 10.46 1.40
0.484 0.57 21.73 2.91
0.825 0.97 37.04 4.95
1.257 1.48 56.43 7.55
1.779 2.09 79.87 10.68
3.905 4.59 175.32 23.44
4.772 5.61 214.24 28.65
6.812 8.01 305.83 40.89
9.213 10.83 413.63 55.30
11.977 14.09 537.72 71.90
18.665 21.95 837.98 112.04
26.832 31.56 1204.65 161.07
46.869 55.12 2104.22 281.34
Refrigerant weight per 100 feet of pipe is based on 105°F condensing temperature and 10°F sub-cooling, 140°F discharge temperature, and 40°F saturated suction temperature.
Application Guide AG 31-011 61
Figure 21 - R-22 Suction Gas Velocity
Figure 21 is based on 40°F Suction temperature and 105°F condensing temperature. For other conditions, apply correction factors from Table 22.
Table 22 - R-22 Suction Gas Velocity Correction Factors
Cond
Temp (°F)
Suction Temperature (°F)
10 15 20 25 30 35 40 45 50
120
125
130
135
140
145
85
90
95
100
105
110
115
62 Application Guide AG 31-011
Figure 22 - R-134a Suction Gas Velocity
Figure 22 is based on 40°F Suction temperature and 105°F condensing temperature. For other conditions, apply correction factors from Table 23
.
Table 23 - R-134a Suction Gas Velocity Correction Factors
Cond
Temp (°F)
Suction Temperature (°F)
10 15 20 25 30 35 40 45 50
105
110
115
120
85
90
95
100
125
130
135
140
145
Application Guide AG 31-011 63
Figure 23 - R-410A Suction Gas Velocity
Figure 23 is based on 40°F Suction temperature and 105°F condensing temperature. For other conditions, apply correction factors from Table 24.
Table 24 - R-410A Suction Gas Velocity Correction Factors
Cond
Temp (°F)
Suction Temperature (°F)
10 15 20 25 30 35 40 45 50
105
110
115
120
125
85
90
95
100
130
135
140
145
64 Application Guide AG 31-011
Figure 24 - R-407C Suction Gas Velocity
Figure 24 is based on 40°F Suction temperature and 105°F condensing temperature. For other conditions, apply correction factors from Table 25.
Table 25 - R-407C Suction Gas Velocity Correction Factors
Cond
Temp (°F)
Suction Temperature (°F)
10 15 20 25 30 35 40 45 50
115
120
125
130
135
140
145
85
90
95
100
105
110
Application Guide AG 31-011 65
Figure 25 - R-22 Discharge Gas Velocity
Figure 25 is based on 40°F Suction temperature and 105°F condensing temperature. For other conditions, apply correction factors from Table 26.
Table 26 R-22 Discharge Gas Velocity Correction Factors
Cond
Temp (°F)
Suction Temperature (°F)
115
120
125
130
135
140
145
85
90
95
100
105
110
66 Application Guide AG 31-011
Figure 26 - R-134a Discharge Gas Velocity
Figure 26 is based on 40°F Suction temperature and 105°F condensing temperature. For other conditions, apply correction factors from Table 27.
Table 27 - R-134a Suction Gas Velocity Correction Factors
Cond
Temp (°F)
Suction Temperature (°F)
115
120
125
130
135
140
145
85
90
95
100
105
110
Application Guide AG 31-011 67
Figure 27 - R-410A Discharge Gas Velocity
Figure 27 is based on 40°F Suction temperature and 105°F condensing temperature. For other conditions, apply correction factors from Table 28.
Table 28 - R-410A Suction Gas Velocity Correction Factors
Suction Temperature (°F)
Cond
Temp (°F)
105
110
115
120
125
85
90
95
100
130
135
140
145
68 Application Guide AG 31-011
Figure 28 - R-407C Discharge Gas Velocity
Figure 28 is based on 40°F Suction temperature and 105°F condensing temperature. For other conditions, apply correction factors from Table 29
Table 29 - R-407C Suction Gas Velocity Correction Factors
Suction Temperature (°F)
Cond
Temp (°F)
120
125
130
135
140
145
85
90
95
100
105
110
115
Application Guide AG 31-011 69
Appendix 3 – Refrigerant Piping Tables (SI)
22
28
15
18
35
42
54
67
130
156
79
92
105
206
Table 30 - Copper Tube Data
Nominal
Dia. Type
Wall
Dia. Diameter Surface
Outside
D, (mm)
Inside d (mm)
Outside
(m²/m)
Inside
(m²/m)
Metal
Area
(mm²)
Flow
Area
(mm²)
Tube
(kg/m)
Working Pressure
ASTM B88 To 120°C
Annealed
(MPa)
Drawn
(MPa)
L 0.89 12.70 10.92 0.040 0.0344 33 94 0.295 4.399 8.253
K 1.24 15.88 13.39 0.050 0.0421 57 141 0.512 4.930 9.246
L 1.02 15.88 13.84 0.050 0.0436 48 151 0.424 4.027 7.543
K 1.24 19.05 16.56 0.060 0.0521 70 215 0.622 4.109 7.702
L 1.07 19.05 16.92 0.060 0.0530 60 225 0.539 3.523 6.605
K 1.65 22.23 18.92 0.070 0.0594 106 281 0.954 4.668 8.757
L 1.14 22.23 19.94 0.070 0.0628 75 312 0.677 3.234 6.061
K 1.65 28.58 25.27 0.090 0.0792 139 502 1.249 3.634 6.812
L 1.27 28.58 26.04 0.090 0.0817 109 532 0.973 2.792 5.240
K 1.65 34.93 31.62 0.110 0.0994 173 785 1.543 2.972 5.571
L 1.40 34.93 32.13 0.110 0.1009 147 811 1.316 2.517 4.716
K 1.83 41.28 37.62 0.130 0.1183 226 1111 2.025 2.786 5.226
L 1.52 41.28 38.23 0.130 0.1201 190 1148 1.701 2.324 4.351
K 2.11 53.98 49.76 0.170 0.1564 343 1945 3.070 2.455 4.606
L 1.78 53.98 50.42 0.170 0.1585 292 1997 2.606 2.069 3.951
K 2.41 66.68 61.85 0.209 .01942 487 3004 4.35 2.275 4.268
L 2.03 66.68 62.61 0.209 0.1966 413 3079 3.69 1.917 3.592
K 2.77 79.38 73.84 0.249 0.2320 666 4282 5.96 2.193 4.109
L 2.29 79.38 74.80 0.249 0.2350 554 4395 4.95 1.813 3.392
K 3.05 92.08 85.98 0.289 0.2701 852 5806 7.62 2.082 3.903
L 2.54 92.08 87.00 0.289 0.2733 714 5944 6.39 1.738 3.254
97.97 0.329 2.041 3.827
99.19 0.329 1.675 3.144
0.409 1.965 3.682
0.409 1.531 2.875
0.489 1.972 3.696
17
ASHRAE Handbook HVAC Systems And Equipment, Chapter 41, 2004. © American Society of
Heating, Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org
.
70 Application Guide AG 31-011
Table 31 - Equivalent Length For Fittings (meters)
Nominal
Dia.
90°
Std
90°
Long
Radius
Smooth Elbows
90°
Street
45°
Std
45°
Street
180°
Std
Tee
Smooth Bend Tee Connections
Straight Through Flow
Branch
Flow
No
Reduction
Reduced
25%
Reduced
50%
105
130
156
206
12 0.4 0.3 0.7 0.2 0.3 0.7 0.8 0.3 0.4 0.4
0.4 0.8 0.9 0.3 0.4 0.5
22
0.6 0.4 1.0 0.3 0.5 1.0 1.2 0.4 0.6 0.6
28
35
42
54
67
79
90
0.8 0.5 1.2 0.4 0.6 1.2 1.5 0.5 0.7 0.8
1.0 0.7 1.7 0.5 0.9 1.7 2.1 0.7 0.9 1.0
1.2 0.8 1.9 0.6 1.0 1.9 2.4 0.8 1.1 1.2
1.5 1.0 2.5 0.8 1.4 2.5 3.0 1.0 1.4 1.5
1.8 1.2 3.0 1.0 1.6 3.0 3.7 1.2 1.7 1.8
2.3 1.5 3.7 1.2 2.0 3.7 4.6 1.5 2.1 2.3
2.7 1.8 4.6 1.4 2.2 4.6 5.5 1.8 2.4 2.7
257
300
3.0 2.0 5.2 1.6 2.6 5.2 6.4 2.0 2.7 3.0
4.0 2.5 6.4 2.0 3.4 6.4 7.6 2.5 3.7 4.0
4.9 3.0 7.6 2.4 4.0 7.6 9 3.0 4.3 4.9
6.1 4.0 - 3.0 - 10 12 4.0 5.5 6.1
7.6 4.9 - 4.0 - 13 15 4.9 7.0 7.6
9.1 5.8 - 4.9 - 15 18 5.8 7.9 9.1
Table 32 - Equivalent Length For Valves And Refrigeration Devices (meters)
Nominal
Dia.
12
15
22
28
35
42
54
67
79
90
105
130
156
206
257
300
Globe Or
Solenoid
5.2
5.5
60° Wye
Valve
45° Wye
Valve
Angle
Valve
Gate
Valve
Swing
Check
Sight
Glass
Filter
Drier
Suction
Filter
18
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
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.
19
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org
.
Application Guide AG 31-011 71
Table 33 - R-22 Refrigerant Line Sizing Table (kW)
SST -20 o
C -5 o
C 5 o
C -40 o
C -20 o
C 5 o
C
ΔT (K/m) 0.04 0.02 0.01 0.04 0.02 0.01 0.04 0.02 0.01 0.02 0.02 0.02
Δp
(Pa/m) 378 189 94.6 572 286 143 366 189 183 74.90
OD (mm)
12
15
18
22
28
35
42
54
67
79
105 vel =
0.02
749
0.75 0.51 0.34 1.25 0.87 0.59 1.76 1.20 0.82 2.30 2.44 2.60 7.08 11.24
1.43 0.97 0.66 2.45 1.67 1.14 3.37 2.30 1.56 4.37 4.65 4.95 11.49 21.54
2.49 1.70 1.15 4.26 2.91 1.98 5.85 4.00 2.73 7.59 8.06 8.59 17.41 37.49
4.39 3.00 2.04 7.51 5.14 3.50 10.31 7.07 4.82 13.32 15.15 15.07 26.66 66.18
8.71 5.95 4.06 14.83 44.57 131.0
15.99 10.96 7.48 27.22 18.69 12.8 37.31 25.66 17.59 48.03 51.05 54.37 70.52 240.7
26.56 18.20 12.46 45.17 31.03 21.27 61.84 42.59 29.21 79.50 84.52 90.00 103.4 399.3
52.81 36.26 24.88 89.69 61.79 42.43 122.7 84.60 58.23 157.3 167.2 178.1 174.1 794.2
94.08 64.79 44.48 159.5 110.05 75.68 218.3 150.08 103.80 279.4 297.0 316.3 269.9 1415.0
145.9 100.51 69.04 247.2 170.64 117.39 337.9 233.56 161.10 431.3 458.5 488.2 376.5 2190.9
312.2 215.39 148.34 527.8 365.08 251.92 721.9 499.16 344.89 919.7 977.6 1041.0 672.0 4697.0
Values in Table 33 are based on 40°C condensing temperature. Multiply table capacities by the following factors for other condensing temperatures.
Condensing Temperature (°C)
20
30
40
50
Suction Line
1.18
1.10
1.00
0.91
Discharge Line
0.80
0.88
1.00
1.11
Notes for Table 33:
1. Table Capacities are in kilowatts of refrigeration.
2. Δp = pressure drop per unit equivalent length of line, Pa/m
3. Δt = corresponding change in saturation temperature, K/m
4. Line capacity for other saturation temperatures Δt and equivalent lengths L e
Line Capacity
=
Table Capacity
⎛
⎜⎜
Table
Acutal
L e
L e
×
Actual
Δ
t
Table
Δ
t
⎞
⎟⎟
0 .
55
ΔT for other capacities and equivalent lengths L e
Δ
t
=
Table
Δ
t
⎛
⎜⎜
Actual L e
Table L e
⎞
⎟⎟
⎛
⎜⎜
Actual Capacity
Table Capacity
⎞
⎟⎟
1 .
8
20
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
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.
72 Application Guide AG 31-011
Table 34 - R-134a Refrigerant Line Size Table (kW)
Suction Discharge
SST 0 o
C 5 o
C 10 o
C -10 o
C 0 o
C 10 o
C
ΔT (K/m)
Δp
0.04 0.02 0.01 0.04 0.02 0.01 0.04 0.02 0.01 0.02 0.02 0.02 vel =
0.5
(Pa/m) 425 212 106 487 243 121 555 278 136 538 538 538 m/s
OD
(mm)
0.02
538
12
15
18
22
28
35
42
54
67
79
105
0.92 0.63 0.43 1.11 0.76 0.51 1.33 0.91 0.62 1.69 1.77 1.84 6.51 8.50
1.76 1.20 0.82 2.12 1.45 0.99 2.54 1.74 1.19 3.23 3.37 3.51 10.6 16.30
3.60 2.09 1.43 3.69 2.53 1.72 4.42 3.03 2.07 5.61 5.85 6.09 16.0 28.40
5.40 3.69 2.52 6.50 4.46 3.04 7.77 5.34 3.66 9.87 10.3 10.7 24.5 50.1
10.7 7.31 5.01 12.8 8.81 6.02 15.3 10.6 7.24 19.5 20.3 21.1 41.0 99.5
19.5 13.4 9.21 23.5 16.2 11.1 28.1 19.4 13.3 35.6 37.2 38.7 64.9 183.0
32.4 22.3 15.3 39.0 26.9 18.4 46.5 32.1 22.1 59.0 61.6 64.1 95.2 304.0
64.4 44.4 30.5 77.3 53.4 36.7 92.2 63.8 44.0 117.0 122.0 127.0 160.0 605.0
115.0 79.0 54.4 138.0 95.0 65.4 164.0 113.0 78.3 208.0 217.0 226.0 248.0 1080.0
177.0 122.0 84.3 213.0 147.0 101.0 253.0 176.0 122.0 321.0 335.0 349.0 346.0 1670.0
379.0 262.0 181.0 454.0 315.0 217.0 541.0 375.0 260.0 686.0 715.0 744.0 618.0 3580.0
Values in Table 34 are based on 40°C condensing temperature. Multiply table capacities by the following factors for other condensing temperatures.
Condensing Temperature (°C)
20
30
40
50
Suction Line
1.239
1.120
1.0
0.888
Discharge Line
0.682
0.856
1.0
1.110
Notes for Table 34:
1. Table Capacities are in kilowatts of refrigeration.
2. Δp = pressure drop per unit equivalent length of line, Pa/m
3. Δt = corresponding change in saturation temperature, K/m
4. Line capacity for other saturation temperatures Δt and equivalent lengths L e
Line Capacity
=
Table Capacity
⎛
⎜⎜
Table
Acutal
L e
L e
×
Actual
Δ
t
Table
Δ
t
⎞
⎟⎟
0 .
55 e
Δ
t
=
Table
Δ
t
⎛
⎜⎜
Actual L e
Table L e
⎞
⎟⎟
⎛
⎜⎜
Actual Capacity
Table Capacity
⎞
⎟⎟
1 .
8
21
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org
.
Application Guide AG 31-011 73
Table 35 - R-410A Refrigerant Line Size Table
12
15
18
22
28
35
42
54
67
79
105
Suction
SST -20 o
ΔT
C -5 o
C 5 o
C -20 o
C -5 o
C 5 o
C
(K/m) 0.04 0.02 0.01 0.04 0.02 0.01 0.04 0.02 0.01 0.02 0.02 0.02
Δp
(Pa/m) 599.1 299.6 149.8 894.2 447.1 223.6 1137.6 568.8 284.4 1172.1 1172.1 1172.1 vel =
2
0.5 m/s
1179
OD
(mm)
1.20 0.82 0.56 2.05 1.40 0.96 2.83 1.94 1.32 3.84 4.00 4.07 6.2 14.3
2.29 1.57 1.07 3.90 2.68 1.83 5.37 3.69 2.53 7.31 7.60 7.75 10.1 27.2
3.98 2.73 1.86 6.76 4.65 3.19 9.30 6.41 4.39 12.67 13.16 13.42 15.4 47.3
7.00 4.81 3.28 11.89 8.19 5.61 16.32 11.26 7.74 22.20 23.08 23.53 23.5 83.0
13.82 9.51 6.51 23.43 16.15 11.09 32.11 22.19 15.28 43.70 45.42 46.31 39.3 163.7
25.33 17.44 11.95 42.82 29.56 20.38 58.75 40.66 27.99 79.84 82.98 84.62 62.2 299.6
42.00 28.92 19.88 70.89 49.03 33.75 97.02 67.28 46.41 131.87 137.06 139.76 91.3 495.7
83.26 57.48 39.55 140.29 97.22 67.10 191.84 133.10 92.11 260.80 271.06 276.39 153.7 982.0
147.94 102.34 70.53 249.16 172.78 119.50 340.33 236.73 163.91 462.73 480.93 490.40 238.2 1746.4
229.02 158.27 109.33 384.65 267.04 184.82 525.59 365.38 253.23 713.37 741.44 756.03 332.2 2695.2
488.64 338.41 234.20 820.20 569.83 395.31 1119.32 778.82 541.15 1519.45 1579.22 1610.30 592.9 5744.4
Values in Table 35 are based on 40°C condensing temperature. Multiply table capacities by the following factors for other condensing temperatures.
Condensing Temperature (°C)
20
30
40
50
Suction Line
1.238
1.122
1.000
0.867
Discharge Line
0.657
0.866
1.000
1.117
Notes for Table 35:
1. Table Capacities are in kilowatts of refrigeration.
2. Δp = pressure drop per unit equivalent length of line, Pa/m
3. Δt = corresponding change in saturation temperature, K/m
4. Line capacity for other saturation temperatures Δt and equivalent lengths L e
Line Capacity
=
Table Capacity
⎛
⎜⎜
Table
Acutal
L e
L e
×
Actual
Δ
t
Table
Δ
t
⎞
⎟⎟
0 .
55
ΔT for other capacities and equivalent lengths L e
Δ
t
=
Table
Δ
t
⎛
⎜⎜
Actual L e
Table L e
⎞
⎟⎟
⎛
⎜⎜
Actual Capacity
Table Capacity
⎞
⎟⎟
1 .
8
22
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
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.
74 Application Guide AG 31-011
Table 36 - R-407C Refrigerant Line Size Table (kW)
12
15
18
22
28
35
42
54
67
79
105
Suction
SST -20 o
C -5 o
C 5 o
C -20
ΔT o
C -5 o
C 5 o
C
Δp
(Pa/m) 358.5 179.3 89.6 561.9 281 140.5 734.3 367.1 183.6 799.8 799.8 799.8 vel =
0.5 m/s
OD
(mm)
2
854.9
0.65 0.44 0.30 1.19 0.81 0.55 1.72 1.17 0.80 2.47 2.61 2.70 6.5 11.7
1.24 0.85 0.58 2.28 1.56 1.06 3.27 2.24 1.53 4.71 4.98 5.15 10.5 22.3
2.17 1.48 1.00 3.96 2.71 1.85 5.67 3.89 2.66 8.16 8.63 8.91 16.0 38.8
3.82 2.61 1.78 6.97 4.78 3.26 9.98 6.86 4.70 14.34 15.16 15.67 24.5 68.2
7.56 5.17 3.53 13.76 9.45 6.47 19.66 13.54 9.29 28.24 29.85 30.84 40.9 134.8
13.90 9.52 6.51 25.18 17.36 11.9 35.97 24.8 17.06 51.69 54.65 56.47 64.7 247.2
23.04 15.82 10.84 41.76 28.75 19.76 59.52 41.12 28.32 85.46 90.34 93.35 94.9 409.8
45.84 31.50 21.63 82.78 57.14 39.32 117.94 81.62 56.27 169.13 178.79 184.76 159.7 813.2
81.59 56.25 38.59 147.33 101.74 70.12 209.38 145.23 100.33 300.43 317.59 328.18 247.6 1446.8
126.37 87.17 59.91 227.71 157.62 108.68 323.76 224.39 155.40 463.81 490.30 506.66 345.2 2239.0
270.09 186.59 128.63 485.80 337.06 232.78 690.10 479.50 332.20 987.20 1043.58 1078.40 616.2 4783.9
Values in Table 36 are based on 40°C condensing temperature. Multiply table capacities by the following factors for other condensing temperatures.
Suction Line Discharge Line
1.202 0.605
1.103 0.845
1.000 1.000
0.891 1.133
Condensing Temperature (°C)
20
30
40
50
Notes for Table 36:
1. Table Capacities are in kilowatts of refrigeration.
2. Δp = pressure drop per unit equivalent length of line, Pa/m
3. Δt = corresponding change in saturation temperature, K/m
4. Line capacity for other saturation temperatures Δt and equivalent lengths L e
Line Capacity
=
Table Capacity
⎛
⎜⎜
Table
Acutal
L e
L e
×
Actual
Δ
t
Table
Δ
t
⎞
⎟⎟
0 .
55 e
Δ
t
=
Table
Δ
t
⎛
⎜⎜
Actual L e
Table L e
⎞
⎟⎟
⎛
⎜⎜
Actual Capacity
Table Capacity
⎞
⎟⎟
1 .
8
23
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org
.
Application Guide AG 31-011 75
Table 37 - R-22 Minimum Capacity For Suction Riser (kW)
Saturated
Suction
Temp
(°C)
Suction
Gas Temp
Pipe O.D.
(mm)
(°C) 12 15 18 22 28 35 42 54 67 79 105 130
-5
5
-40
-20
-35
-25
-15
-15
-5
5
0
10
20
10
20
30
0.182 0.334 0.561 0.956 1.817 3.223 5.203 9.977 14.258 26.155 53.963 93.419
0.173 0.317 0.532 0.907 1.723 3.057 4.936 9.464 16.371 24.811 51.189 88.617
0.168 0.307 0.516 0.880 1.672 2.967 4.791 9.185 15.888 24.080 49.681 86.006
0.287 0.527 0.885 1.508 2.867 5.087 8.213 15.748 27.239 41.283 85.173 147.449
0.273 0.501 0.841 1.433 2.724 4.834 7.804 14.963 25.882 39.226 80.929 140.102
0.264 0.485 0.815 1.388 2.638 4.680 7.555 14.487 25.058 37.977 78.353 135.642
0.389 0.713 1.198 2.041 3.879 6.883 11.112 21.306 36.854 55.856 115.240 199.499
0.369 0.676 1.136 1.935 3.678 6.526 10.535 20.200 34.940 52.954 109.254 189.136
0.354 0.650 1.092 1.861 3.537 6.275 10.131 19.425 33.600 50.924 105.065 181.884
0.470 0.862 1.449 2.468 4.692 8.325 13.441 25.771 44.577 67.560 139.387 241.302
0.440 0.807 1.356 2.311 4.393 7.794 12.582 24.126 41.731 63.246 130.488 225.896
0.422 0.774 1.301 2.217 4.213 7.476 12.069 23.141 40.027 60.665 125.161 216.675
Refrigeration capacity in kilowatts is based on saturated evaporator as shown in table and condensing temperature of 40 o
C. For other liquid line temperatures, use correction factors in the following table.
Liquid Temperature (°C)
20 30 50
1.17 1.08 0.91
Table 38 - R-134a Minimum Capacity For Suction Riser (kW)
Saturated
Suction
Temp
(°C)
Suction
Gas Temp
Pipe O.D.
(mm)
(°C) 12 15 18 22 28 35 42 54 67 79 105 130
-5
5
-10
10
-35
-25
-15
-15
-5
5
0
10
20
10
20
30
0.274 0.502 0.844 1.437 2.732 4.848 7.826 15.006 25.957 39.340 81.164 140.509
0.245 0.450 0.756 1.287 2.447 4.342 7.010 13.440 23.248 35.235 72.695 125.847
0.238 0.436 0.732 1.247 2.370 4.206 6.790 13.019 22.519 31.129 70.414 121.898
0.296 0.543 0.913 1.555 2.956 5.244 8.467 16.234 28.081 42.559 87.806 152.006
0.273 0.500 0.840 1.431 2.720 4.827 7.792 14.941 25.843 39.168 80.809 139.894
0.264 0.484 0.813 1.386 2.634 4.674 7.546 14.468 25.026 37.929 78.254 135.471
0.357 0.655 1.100 1.874 3.562 6.321 10.204 19.565 33.843 51.292 105.823 183.197
0.335 0.615 1.033 1.761 3.347 5.938 9.856 18.380 31.792 48.184 99.412 172.098
0.317 0.582 0.978 1.667 3.168 5.621 9.075 17.401 30.099 45.617 94.115 162.929
0.393 0.721 1.211 20.63 3.921 6.957 11.232 21.535 37.250 56.456 116.479 201.643
0.370 0.679 1.141 1.944 3.695 6.555 10.583 20.291 35.098 53.195 109.749 189.993
0.358 0.657 1.104 1.881 3.576 6.345 10.243 19.640 33.971 51.486 106.224 183.891
Refrigeration capacity in kilowatts is based on saturated evaporator as shown in table and condensing temperature of 40 o
C. For other liquid line temperatures, use correction factors in the following table.
Liquid Temperature (°C)
20 30 50
1.20 1.10 0.89
24
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org
.
25
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org
.
76 Application Guide AG 31-011
Table 39 - R-410A Minimum Capacity For Suction Riser (kW)
Saturated
Suction
Temp
Suction
Gas
Temp
Pipe O.D.
(mm)
-17
-7
-12 0.586 1.113 1.905 2.93 5.86 10.26 16.1 33.70 60.36 93.8 140.6 196.3
-12 0.674 1.275 2.344 3.37 6.89 12.0 18.8 38.97 68.86 108.4 161.2 225.6
5 -12 0.747 1.406 2.403 3.75 7.62 13.19 21.1 43.66 76.18 123.1 181.7 252.0
Refrigeration capacity in tons is based on 32°C liquid temperature and superheat as indicated by the listed temperature.
Multiply table capacities by the following factors for other liquid line temperatures. (Table data based on line size pressure drop formula shown on page 2.17 of ASHRAE Handbook Refrigeration 2006.)
Liquid Temperature (°C)
27 32 38 43 49 54 60
1.05 1.00 0.94 0.90 0.83 0.77 0.72
Table 40 - R-407C Minimum Capacity For Suction Riser (kW)
Saturated
Suction
Temp
Suction
Gas
Temp
Pipe O.D.
(mm)
-17
-7
5
-12 0.447 0.850 1.450 2.26 4.60 8.06 12.6 26.07 46.00 73.25 108.4 152.4
-12 0.527 0.996 1.699 2.67 5.42 9.38 14.94 30.77 54.21 86.44 128.9 178.7
-12 0.601 1.143 1.934 3.05 6.15 10.8 16.99 35.16 61.53 97.86 146.5 205.1
Refrigeration capacity in tons is based on 32°C liquid temperature and superheat as indicated by the listed temperature. Multiply table capacities by the following factors for other liquid line temperatures. (Table data based on line size pressure drop formula shown on page 2.17 of ASHRAE Handbook Refrigeration 2006.)
Liquid Temperature (°C)
27 32 38 43 49 54 60
1.05 1.00 0.95 0.90 0.85 0.80 0.74
Application Guide AG 31-011 77
Table 41 - R-22 Minimum Capacity For Discharge Riser (kW)
Saturated
Discharge
Temp
(°C)
Discharge
Gas
Temp
Pipe O.D.
(mm)
(°C) 12 15 18 22 28 35 42 54 67 79 105 130
40
50
20
30
70 0.5494 1.006 1.691 2.881 5.477 9.717 15.687 30.078 52.027 48.851 162.682 281.630
Refrigeration capacity in kilowatts is based on saturated evaporator at -5 o
C, and condensing temperature as shown in table. For other liquid line temperatures, use correction factors in the following table.
Saturated Suction Temperature (°C)
-50 -40 -30 -20 0 5 10
0.87 0.90 0.93 0.96 - 1.02 -
Saturated
Discharge
Temp
(°C)
40
20
30
50
Table 42 - R-134a Minimum Capacity For Discharge Riser (kW)
Discharge
Gas
Temp
Pipe O.D.
(mm)
(°C) 12 15 18 22 28 35 42 54 67 79 105 130
60
70
80
70
80
90
80
90
100
90
0.469 0.860 1.445 2.462 4.681 8.305 13.408 25.709 44.469 67.396 139.050 240.718
0.441 0.808 1.358 2.314 4.399 7.805 12.600 24.159 41.788 63.334 130.668 226.207
0.431 0.790 1.327 2.261 4.298 7.626 12.311 23.605 40.830 61.881 127.671 221.020
0.493 0.904 1.519 2.587 4.918 8.726 14.087 27.011 46.722 70.812 145.096 252.916
0.463 0.849 1.426 2.430 4.260 8.196 13.232 25.371 43.885 66.512 137.225 237.560
0.452 0.829 1.393 2.374 4.513 8.007 19.926 24.785 42.870 64.974 134.052 232.066
0.507 0.930 1.563 2.662 5.061 8.979 14.496 27.794 48.075 72.863 150.328 260.242
0.477 0.874 1.469 2.502 4.756 8.439 13.624 26.122 45.184 68.480 141.285 244.588
0.465 0.852 1.432 2.439 4.637 8.227 13.281 25.466 44.048 66.759 137.735 238.443
0.510 0.936 1.573 2.679 5.093 9.037 14.589 27.973 48.385 73.332 151.296 261.918
0.479 0.878 1.476 2.514 4.779 8.480 13.690 26.248 45.402 68.811 141.696
2485.77
2 100
110 0.467 0.857 1.441 2.454 4.665 8.278 13.364 25.624 44.322 67.173 138.590 239.921
Refrigeration capacity in kilowatts is based on saturated evaporator at -5 o
C, and condensing temperature as shown in table. For other liquid line temperatures, use correction factors in the following table.
Saturated Suction Temperature (°C)
-50 -40 -30 -20 0 5 10
26
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org
.
27
ASHRAE Handbook Refrigeration, Chapter 2, 2006. © American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org
.
78 Application Guide AG 31-011
Table 43 – R-410A minimum Capacity For Discharge Riser (kW)
Saturated
Suction
Temp
Discharge
Temp
Pipe O.D.
(mm)
(°C) (°C) 12 15 18 22 28 35 42 54 67 79 92 105
27
38
60
71
1.160 2.15 3.727 5.590 11.2 19.5 30.8 48.5 85.79 136.8 203.2 287.3
1.195 2.21 3.839 5.758 11.6 20.1 31.7 49.9 88.36 140.9 209.3 295.9
49 82 1.231 2.28 3.954 5.931 11.9 20.7 32.6 51.4 91.02 145.1 215.6 304.8
Refrigeration capacity in tons based on saturated suction temperature of 4 saturated condensing temperature with -10 o o
C with -10 o
C superheat at indicated
C sub-cooling. For other saturated suction temperatures with -10 o
C superheat, use correction factors in the following table. (Table data based on line size pressure drop formula shown on page 2.17 of ASHRAE Handbook Refrigeration 2006.)
Saturated Suction Temperature (°C)
-18 -7 4 16
0.90 0.94 1.00 1.06
Table 44 - R-407C Minimum Capacity For Discharge Riser (kW)
Saturated
Suction
Temp
Discharge
Temp
Pipe O.D.
(mm)
(°C) (°C) 12 15 18 22 28 35 42 54 67 79 92 105
27
38
60
71
1.020 1.87 3.210 4.887 9.81 17.1 26.9 42.54 74.89 119.6 178.3 251.0
1.050 1.92 3.306 5.034 10.1 17.6 27.8 43.82 77.14 123.1 183.7 258.6
49 82 1.082 1.98 3.406 5.185 10.4 18.1 28.6 45.14 79.45 126.8 189.1 266.3
Refrigeration capacity in tons based on saturated suction temperature of 4 saturated condensing temperature with -10 o o
C with -10 o
C superheat at indicated
C sub-cooling. For other saturated suction temperatures with -10 o
C superheat, use correction factors in the following table. (Table data based on line size pressure drop formula shown on page 2.17 of ASHRAE Handbook Refrigeration 2006.)
Saturated Suction Temperature (°C)
-18 -7 4 16
0.96 0.98 1.00 1.02
Application Guide AG 31-011 79
Table 45 - R-22 Refrigerant Charge (kg Per 30.5 meters of Pipe)
Line Size Flow Suction Line Liquid Line Discharge Line
OD Area
4.44
o
C 40.56
o
C 60 o
C
92
105
130
156
206
28
35
42
54
67
79
mm mm
2 kg/m
3
12
15
22
kg/m
3
94 0.07 3.15
151 0.11
312 0.23
5.07
10.47
532 0.39 17.85
811 0.60 27.21
1148 0.85 38.52
2519 1.87 84.52 kg/m
3
0.32
0.51
1.06
1.81
2.76
3.91
8.57
3079 2.29 103.31 10.48
4935 3.66 165.58 16.79
5944 4.41 199.43 20.23
7727 5.73 259.26 26.30
12042 8.94 404.03
17311 12.85 580.82
40.98
58.91
30238 22.44 1014.55 102.90
Refrigerant weight per 30.5 meters of pipe is based on 40.56°C condensing temperature, 60°C discharge temperature, and 4.44°C saturated suction temperature.
Table 46 - R-134a Refrigerant Charge (kg Per 30.5 meters of Pipe)
Line Size
OD
Flow
Area
Suction Line Liquid Line Discharge Line
4.44
o
C 40.56
o
C 60 o
C
54
67
79
92
105
130
12
15
22
28
35
42
mm mm
2 kg/m
3 kg/m
3 kg/m
3
94 0.05 3.21
151 0.08 5.16
312 0.16 10.65
532 0.27 18.16
0.25
0.40
0.83
1.42
811 0.42 27.69
1148 0.59 39.20
2519 1.29 86.01
3079 1.58 105.13
2.16
3.06
6.72
8.21
4935 2.53 168.49 13.16
5944 3.05 202.94 15.85
156
206
7727 3.96
12042 6.17
263.82
411.15
17311 8.87 591.05
30238 15.50 1032.41
20.60
32.10
46.15
80.61
Refrigerant weight per 30.5 meters of pipe is based on 40.56°C condensing temperature, 60°C discharge temperature, and 4.44°C saturated suction temperature.
80 Application Guide AG 31-011
Table 47 - R-410A Refrigerant Charge (kg Per 30.5 meters of Pipe)
Line Size Flow Suction Line Liquid Line Discharge Line
67
79
92
105
130
156
206
12
15
22
28
35
42
54
OD Area
4.44
o
C 40.56
o
C 60 o
C mm mm
2 kg/m
3 kg/m
3 kg/m
3
94 0.10 2.68 0.58
151 0.16 4.30 0.93
312 0.34 8.89 1.91
532 0.57 15.16 3.26
811 0.88 23.11 4.98
1148 1.24 32.71 7.05
2519 2.72 71.77 15.46
3079 3.32 87.73 18.90
4935 5.32 140.61 30.29
5944 6.41 169.36 36.48
7727 8.34 220.16 47.42
12042 12.99 343.11 73.90
17311 18.68 493.24 106.24
30238 32.63 861.56 185.58
Refrigerant weight per 30.5 meters of pipe is based on 40.56°C condensing temperature, 60°C discharge temperature, and 4.44°C saturated suction temperature.
Table 48 - R-407C Refrigerant Charge (kg Per 30.5 meters of Pipe)
Line Size
OD
Flow
Area
Suction Line Liquid Line Discharge Line
4.44
o
C 40.56
o
C 60 o
C
35
42
54
67
79
92
mm mm
2 kg/m
3
12
15
22
28
94 0.08 2.97
151 0.12 4.77
312 0.26
532 0.44 kg/m
3
9.85
16.79
811 0.67 25.60
1148 0.95 36.24
2519 2.08 79.51
3079 2.54 97.19
105
130
156
206
kg/m
3
0.40
0.64
1.32
2.24
3.42
4.84
10.63
12.99
4935 4.07 155.77 20.82
5944 4.90 187.62 25.07
7727 6.38 243.90 32.60
12042 9.94 380.10 50.80
17311 14.28 546.42
30238 24.95 954.46
73.03
127.56
Refrigerant weight per 30.5 meters of pipe is based on 40.56°C condensing temperature, 60°C discharge temperature, and 4.44°C saturated suction temperature.
Application Guide AG 31-011 81
Figure 29 - R-22 Suction Gas Velocity
Figure 29 is based on 4.4°C Suction temperature and 41°C condensing temperature. For other conditions, apply correction factors from Table 49.
Table 49 - R-22 Suction Gas Velocity Correction Factors
Cond
Temp (
°
C)
Suction Temperature (
°
C)
-12.2 -9.4 -6.7 -3.9 -1.1 1.7 4.5 7.2 10.0
48.9
51.7
54.5
57.3
60.0
62.8
29.5
32.2
35.0
37.8
40.6
43.4
46.1
82 Application Guide AG 31-011
Figure 30 - R-134a Suction Gas Velocity
Figure 30 is based on 4.4°C Suction temperature and 41°C condensing temperature. For other conditions, apply correction factors from Table 50.
Table 50 - R-134a Suction Gas Velocity Correction Factors
Cond
Temp (
°
C)
Suction Temperature (
°
C)
-12.2 -9.4 -6.7 -3.9 -1.1 1.7 4.5 7.2 10.0
46.1
48.9
51.7
54.5
57.3
60.0
62.8
29.5
32.2
35.0
37.8
40.6
43.4
Application Guide AG 31-011 83
Figure 31 - R-410A Suction Gas Velocity
Figure 31 is based on 4.4°C Suction temperature and 41°C condensing temperature. For other conditions, apply correction factors from Table 51.
Table 51 - R-410A Suction Gas Velocity Correction Factors
Cond
Temp (
°
C)
Suction Temperature (
°
C)
-12.2 -9.4 -6.7 -3.9 -1.1 1.7 4.5 7.2 10.0
29.5
32.2
35.0
37.8
40.6
43.4
46.1
48.9
51.7
54.5
57.3
60.0
62.8
84 Application Guide AG 31-011
Figure 32 - R-407C Suction Gas Velocity
Figure 32 is based on 4.4°C Suction temperature and 41°C condensing temperature. For other conditions, apply correction factors from Table 52.
Table 52 - R-407C Suction Gas Velocity Correction Factors
Cond
Temp (
°
C)
Suction Temperature (
°
C)
-12.2 -9.4 -6.7 -3.9 -1.1 1.7 4.5 7.2 10.0
51.7
54.5
57.3
60.0
62.8
29.5
32.2
35.0
37.8
40.6
43.4
46.1
48.9
Application Guide AG 31-011 85
Figure 33 - R-22 Discharge Gas Velocity
Figure 33 is based on 28°C discharge temperature and 5°C condensing temperature. For other conditions, apply correction factors from Table 53.
Table 53 R-22 Discharge Gas Velocity Correction Factors
Cond
Temp (
°
C)
Suction Temperature (
°
C)
46.1
48.9
51.7
54.5
57.3
60.0
62.8
29.5
32.2
35.0
37.8
40.6
43.4
86 Application Guide AG 31-011
Figure 34 - R-134a Discharge Gas Velocity
Figure 34 is based on 28°C discharge temperature and 5°C condensing temperature. For other conditions, apply correction factors from Table 54.
Table 54 - R-134a Discharge Gas Velocity Correction Factors
Cond
Temp (
°
C)
Suction Temperature (
°
C)
48.9
51.7
54.5
57.3
60.0
62.8
29.5
32.2
35.0
37.8
40.6
43.4
46.1
Application Guide AG 31-011 87
Figure 35 - R-410A Discharge Gas Velocity
correction factors from Table 55.
Table 55 - R-410A Discharge Gas Velocity Correction Factors
Cond
Temp (
°
C)
Suction Temperature (
°
C)
46.1
48.9
51.7
54.5
57.3
60.0
62.8
29.5
32.2
35.0
37.8
40.6
43.4
88 Application Guide AG 31-011
Figure 36 - R-407C Discharge Gas Velocity
Figure 36 is based on 28°C discharge temperature and 5°C condensing temperature. For other conditions, apply correction factors from Table 56
.
Table 56 - R-407C Discharge Gas Velocity Correction Factors
Cond
Temp (
°C
)
Suction Temperature (
°C
)
29.5
32.2
35.0
37.8
40.6
43.4
46.1
48.9
51.7
54.5
57.3
60.0
62.8
Application Guide AG 31-011 89
Notes
90 Application Guide AG 31-011
Application Guide AG 31-011 91
advertisement
Key Features
- R-22, R-407C, R-410A, and R-134a refrigerant support
- Size refrigerant piping
- Commercial air conditioning systems
- Avoid liquid refrigerant slugging
- Adequate refrigerant flow
- Sufficient oil return
- Clean and dry piping
