Air-Cooled Screw Compressor Chiller Installation, Operation and Maintenance Manual 60 Hertz

Air-Cooled Screw Compressor Chiller Installation, Operation and Maintenance Manual 60 Hertz

CAUTION

Do not use automotive grade antifreeze. Industrial grade glycols must be used. Automotive antifreeze contains inhibitors that will cause plating on the copper tubes within the chiller evaporator. The type and handling of glycol used must be consistent with local codes.

Table 3, Propylene Glycol

%

P.G.

10

20

30

40

50

FREEZE

POINT.

o

F o

C

26

19

-3

-7

9

-5

-13

-21

-27 -33

CAP

0.987

0.975

0.962

0.946

0.965

POWER

0.992

0.985

0.978

0.971

0.965

FLOW

1.010

1.028

1.050

1.078

1.116

PD

1.068

1.147

1.248

1.366

1.481

Table 4, Ethylene Glycol

%

E.G.

10

20

30

40

50

FREEZE

POINT.

o

F o

C

26

18

7

-7

-28

-3

-8

-14

-22

-33

CAP

0.991

0.982

0.972

0.961

0.946

POWER

0.996

0.992

0.986

0.976

0.966

FLOW

1.013

1.040

1.074

1.121

1.178

PD

1.070

1.129

1.181

1.263

1.308

Remote Evaporator

General

The multiple compressor ALS air-cooled chillers are available with the evaporator shipped loose for remote mounting. This allows the main unit to be installed outdoors to save interior room and eliminates the need for anti-freeze solutions and heat tracing of chilled water lines since the chilled water system is indoors. There are some general guidelines to review before proceeding:

1. R-22 only.

2. Maximum line length of 50 ft (15 m) and Total Equivalent Length (TEL) of 120 ft (37 m).

3. Evaporator not more than 6 ft (1.8 m) above the compressor or 16 ft (5 m) below compressor.

4. No underground piping.

5. No hot gas bypass.

6. Units with remote evaporator are not included in the ARI Certification Program.

The remote evaporator is shipped separately, ready for quick and easy installation at the job site. All refrigerant accessories such as liquid-vapor line shut-off valves, replaceable core filter-driers, liquid line solenoid valves, electronic expansion valves, and sightglasses are already included on the ALS condensing unit. The evaporator is equipped with entering and leaving chilled water temperature sensor wells. The sensors are pre-wired to the ALS unit with 75 feet long sensor leads and must be field connected to the evaporator thermowells. Suction pressure transducers and temperature sensors must also be relocated to the evaporator. ALS units are factory charged with a full unit charge pumped down into the condensers. Field piping must be leak tested, evacuated and charged during installation. Do not exceed 150 psig test pressure unless the unit is blanked off from the piping.

Performance Derate Factors

All performance tables and adjustment factors found in the current version of the Air-Cooled Screw

Chiller catalog (PM ALS-x) are applicable for remote evaporator installations. However, a performance derate must be applied to the R-22 performance data due to additional pressure drops in the suction and liquid lines which cause a loss of compressor performance. These derates are based on a suction line pressure drop equivalent of approximately 2°F (1°C) change in saturation temperature.

For R-22 applications:

Capacity = Tons (kW) x 0.97

Power = Compressor kW x 0.99

IOMM ALS-4

13

14

Refrigerant Piping

General

Careful design of the refrigerant piping is necessary for efficient system operation. The refrigerant piping should be designed for a low refrigerant pressure drop to obtain maximum capacity and efficiency while maintaining adequate velocity. Lines should slope in the direction of flow to assure good oil return to the compressors. Cost considerations favor keeping line sizes as small as possible while not exceeding acceptable pressure drops in order to maintain unit performance.

NOTE

All refrigerant piping must be reviewed and approved by McQuay Application

Engineers prior to order entry and will be verified by McQuay startup technicians.

Equivalent Line Lengths

Recommended refrigerant line sizes are based on equivalent line lengths of straight pipe, that is, a combination of straight pipe, fittings and valves. The pressure drop through valves and fittings is determined by establishing the equivalent straight length of pipe of the same size with the same friction loss. The "Total Equivalent Length" is the sum of the "Lineal Line Length" and the appropriate "Valve and Fitting Losses in Equivalent Feet of Pipe for Field Supplied Piping" given in

Table 5

Table 5, Fitting Equivalent Feet of Pipe

Line Size (in.)

1 1/8

1 3/8

1 5/8

2 1/8

2 5/8

3 1/8

Angle Valve

12

15

18

24

29

35

Globe Valve

29

38

43

55

69

84

90° Std. Radius Elbow 90° Long Radius Elbow

2.6

3.3

4.0

5.0

6.0

7.5

1.7

2.3

2.6

3.3

4.1

5.0

Location and Arrangement

Refrigerant lines should be as short and direct as possible to minimize tubing and fittings. Long radius elbows must be used (except for traps) to minimize the pressure drops. Traps should be as short as possible to minimize oil accumulation. Refrigerant piping should be arranged so that normal inspection of the equipment is not hindered. Adequate clearance should be provided between refrigerant piping and adjacent walls for insulation. Piping should be run so that it does not interfere with compressor service access, passages or obstruct headroom, windows and doors. Suction line hangers must be sized and located to support the weight of the piping in accordance with good piping practice.

Horizontal portions of the suction lines must be downward sloping toward the compressors. Slope all piping in the direction of flow. Vertical portions of the suction lines must be sized for oil return at minimum compressor load.

Note:

Double section risers must not be utilized on any circuit. Traps must be provided as shown on

Figure 9 and Figure 10.

Suction Line Sizing

Pressure drop in the suction line reduces system capacity and efficiency because it forces the compressor to operate at lower suction pressure. The suction line should be sized for a pressure drop approximately equivalent of 2°F (1

°

C) change in saturation temperature. For suction line sizing see

Table 7 and Table 8. For applications with the evaporator below the ALS unit, the vertical section of

the suction lines must be sized to return oil to the compressors at the minimum compressor capacity step.

IOMM ALS-4

IOMM ALS-4

Example of Suction Line Size Calculation

ALS150C condensing unit with refrigerant R-22

Evaporator located 5 feet below the ALS compressor

Lineal length of horizontal suction line is 25 feet

Suction line requires 7 long radius (90°) elbows; 3 in the horizontal, 4 in the riser

From Table 6, the nominal circuit capacities for circuit 1 and 2 are 65 and 80 tons respectively

Total lineal suction line length = 30 feet each circuit (25 feet horizontal plus 5 feet vertical riser).

For the first try, assume that the total equivalent suction line length is twice the lineal suction line length.

Therefore the estimated total equivalent suction line length = 60 feet

From Table 7 and Table 8, For nominal circuit capacities of 65 & 80 tons and total equivalent line

length of 60 ft, the suction line size = 2 5/8" for horizontal lines and 2 1/8" for vertical lines.

From Table 5, Fitting loss for 2 5/8" long radius (90°) elbow = 4.1 ft, and 3.3 ft for the 2 1/8 elbows.

Therefore fitting loss in equivalent feet of pipe for (3) 2 5/8" long radius (90°) elbow = 12.3 ft, and 13.2 ft for (4) 2 1/8" elbows.

Therefore the actual equivalent suction line length = 30 + 12.3 + 13.2 = 55.5 feet

From and Table 8, For nominal circuit capacities of 65 & 80 tons and equivalent line length of 55.5 ft

the suction line size is correct.

Table 6, ALS 141C-420C Nominal Circuit Capacities

ALS Model

141

150

171

186

190

200

206

218

Circuit 1

Tons (kW)

65 (229)

65 (229)

80 (262)

80 (262)

80 (262)

95 (334)

95 (334)

95 (334)

Circuit 2

Tons (kW)

65 (229)

80 (262)

80 (262)

95 (334)

95 (334)

95 (334)

95 (334)

95 (334)

Table 7, Vertical Upflow Suction Line Sizes

Nominal Circuit

Capacity

Tons (kW)

65 (229)

80 (262)

95 (334)

Vertical Upflow Suction Lines

Equivalent Line Length Ft (m) Suction Line Size (in.)

40 (12)

75 (23)

40 (12)

75 (23)

40 (12)

75 (23)

2 1/8

2 1/8

2 1/8

2 1/8

2 5/8

2 5/8

Table 8, Horizontal and Vertical Downflow Suction Line Sizes

Vertical Downflow and Horizontal Suction Lines Nominal Circuit

Capacity

Tons (kW)

65 (229)

80 (262)

95 (334)

Equivalent Line Length Ft (m)

40 (12)

75 (23)

115 (35)

40 (12)

75 (23)

115 (35)

40 (12)

75 (23)

115 (35)

Suction Line Size, in.

2 5/8

2 5/8

2 5/8

2 5/8

2 5/8

3 1/8

2 5/8

3 1/8

3 1/8

15

16

Liquid-Vapor Lines

The liquid-vapor line from the ALS condensing unit to the evaporator liquid connection is not a conventional liquid line since it carries both liquid and vapor. The compressors on the ALS units utilize a liquid cooled motor and an economizer. Therefore the expansion valve which feeds the full flow of liquid refrigerant into the compressor for motor cooling is mounted in the liquid line between the condenser sub-cooling coil and the compressor inlet, not at the evaporator inlet. The liquid-vapor line to the evaporator is a low-pressure line downstream of the expansion valve and the size is slightly

larger than a normal liquid line. For liquid line sizing see Table 9 and Table 10.

Table 9, Vertical Upflow Liquid-Vapor Line Sizes

Nominal Circuit

Capacity

Tons (kW)

65 (229)

80 (262)

95 (334)

Vertical Upflow Liquid-Vapor Lines

Equivalent Line Length

Ft (m)

Liquid-Vapor Line Size o.d (in.)

40 (12)

75 (23)

1 3/8

1 3/8

40 (12)

75 (23)

40 (12)

75 (23)

1 3/8

1 3/8

1 5/8

1 5/8

Table 10, Horizontal and Vertical Downflow Liquid-Vapor Line Sizes

Nominal Circuit

Capacity

Tons (kW)

65 (229)

80 (262)

95 (334)

Vertical Downflow and Horizontal Liquid-Vapor Lines

Equivalent Line Length

Ft (m)

Liquid-Vapor Line Size

o.d (in.)

40 (12)

75 (23)

115 (35)

1 3/8

1 3/8

1 3/8

40 (12)

75 (23)

115 (35)

40 (12)

75 (23)

115 (35)

1 3/8

1 5/8

1 5/8

1 5/8

1 5/8

1 5/8

Figure 9, Evaporator Above ALS Unit

Evaporator

Trap

ALS Unit

Suction Line

Figure 10, Evaporator Below ALS Unit

ALS Unit

Suction Line

Evaporator

Trap

NOTE: Keep the trap width at a minimum to avoid trapping excessive oil.

IOMM ALS-4

IOMM ALS-4

Insulation

All piping joints and fittings must be thoroughly leak tested before insulation is applied. Suction lines must be insulated and should not be installed underground. Suction line insulation must be selected to prevent condensation under local ambient conditions with the lines at 40°F to 50°F (4.4

°

C to 10

°

C) operating temperatures. The liquid-vapor lines will operate at 40°F to 60°F (4.4

°

C to 15.6

°

C) and

must

also be insulated to prevent sweating and heat gain.

Startup Procedures

NOTE

: McQuayService or a factory authorized McQuay service agent must do initial start-up and commissioning.

Filter Driers

Following an initial 24 hour operation the pressure drop across the replaceable core filter-drier should

be checked. If this pressure drop exceeds the values given in Table 11 at the various load conditions

the filter drier cores must be replaced. Also if the moisture indicating sight glass shows a wet system condition after 24 hours of operation the filter cores must be changed. This should remove any contaminants introduced during field piping. The filter drier cores must also be changed anytime the system is opened for servicing.

Table 11, Filter Drier Pressure Drop

Percent Circuit

Loading (%)

100

75

50

25

Maximum Recommended Pressure Drop Across Filter Drier

psig (kPa)

7 (48.3)

5 (34.5)

3 (20.7)

3 (20.7)

Refrigerant and Oil Charge

The relative position of the ALS unit and the evaporator and the distance between them plays a critical role in determining suction and liquid line sizes and the field refrigerant and oil charges. ALS units with the remote evaporator option are shipped with a unit operating charge of refrigerant and oil.

It will be necessary to evacuate the evaporator and field installed line and top off the charge See

Table 12 for refrigerant charge for suction and liquid-vapor lines. McQuay Service will supply and

add additional oil as required. The correct oil is Planetelf

ACD68AW, McQuay Part No.

735030439 (5 gal.), 735030438 (1 gal.).

Charging Procedure

The calculated refrigerant charge must be added through the factory supplied charging valve located on the liquid-vapor line coming out of the compressor. Sufficient charge must be added to clear the liquid line sight glass located at the outlet of the condenser. Add an extra 10 lb. of refrigerant after the sight glass is clear.

Table 12, Refrigerant Charge for Suction and Liquid-Vapor Lines

Lineal Tubing

Length ft (m)

10 (3)

20 (6)

30 (9)

40 (12)

Notes: See next page

Suction Line Refrigerant Charge

lb (kg)

Line (in.)

2 1/8

2 5/8

3 1/8

R-22

0.33 (0.15)

0.51 (0.23)

0.71 (0.32)

2 1/8

2 5/8

3 1/8

2 1/8

2 5/8

3 1/8

2 1/8

2 5/8

3 1/8

0.66 (0.30)

1.02 (0.46)

1.42 (0.64)

0.99 (0.45)

1.53 (0.69)

2.13 (0.96)

1.32 (0.60)

2.04 (0.92)

2.84 (1.29)

Liquid-Vapor Line Refrigerant Charge lb (kg)

Line (in.)

1 3/8

1 5/8

R-22

3.6 (1.6)

5.0 (2.3)

1 3/8

1 5/8

1 3/8

1 5/8

1 3/8

1 5/8

7.2 (3.3)

10.0 (4.5)

10.8 (4.9)

15.0 (6.8)

14.4 (6.5)

20.0 (9.0)

17

1. The only approved oil is that identified on the label attached to the compressors. All POE oils are hygroscopic and care should be exercised in handling the oil to avoid absorption and retention of moisture.

2. Do not leave the oil container open for more than a minute while charging oil. Do not use oil that has not been properly sealed and stored.

3. Charge must never be added through the compressor suction line

Dimensions

Use the ALS dimension drawings Figure 14 for the ALS with remote evaporator. The refrigerant

connections are located approximately where the refrigerant connections to the unit mounted

evaporator are on a packaged chiller. The remote evaporator dimensions are Figure 11 Figure 12.

Dimensions, Remote Evaporator

Figure 11, Evaporator for ALS 141 - ALS 200

18

ALS

Model

Evaporator

Model

Water

Volume gal. (l)

141 CDE350332801 34 (128)

150-200 CDE350332901 40 (150)

Refrigerant

Volume cu. ft. (L)

1.4 (40.0)

1.8 (52.4)

Unit Weights lb. (kg)

Operating Shipping

934 (424)

1127 (512)

635 (288)

758 (343)

R-22 Operating Charge lb. (kg)

Circuit 1 Circuit 2

34 (15.4)

45 (20.4)

34 (15.4)

45 (20.4)

ALS

Model

141

150-200

Overall Dimensions in. (mm)

Length "K" Height "A"

94.6 (2403)

95.5 (2426)

17.8 (452)

18.4 (467)

"B" "C" "D" "H" "J"

Conn.

"G"

11.0 (279) 10.2 (259) 12.8 (325) 6.4 (163) 85.2 (2164) 5 (152)

12.0 (305) 10.2 (259) 14.0 (356) 6.8 (173) 84.0 (2134) 8 (203)

IOMM ALS-4

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