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4057450/4
DFG300
Automatic or Manual Actuated
Boiler Blowdown Valves
Installation and Maintenance Instructions
IM-P405-38
AB Issue 4
DFG300A
DFG300AX
1. Safety information
2. General
product information
3. Installation
4. Operation
5. Maintenance
6. Spare parts
DFG300M
DFG300MX
2
IM-P405-38 AB Issue 4
1. Safety information
Safe operation of these products can only be guaranteed if they are properly installed, commissioned, used and maintained by qualified personnel (see Section 1.11) in compliance with the operating instructions. General installation and safety instructions for pipeline and plant construction, as well as the proper use of tools and safety equipment must also be complied with.
1.1 Intended use
Referring to the Installation and Maintenance Instructions, name-plate and Technical
Information Sheet, check that the product is suitable for the intended use/application.
The products listed below comply with the requirements of the European Pressure
Equipment Directive 97 / 23 / EC and carry the mark when so required. It should be noted that products rated as 'SEP' are required by the Directive not to carry the mark.
The products fall within the following European Pressure Equipment Directive categories:
DFG300A
Product
DN25 and DN32
DN40 and DN50
Group 1 Group 2 Group 1 Group 2
Gases Gases Liquids Liquids
2 SEP SEP SEP
2
2
1
SEP
SEP
SEP
SEP
SEP DFG300AX
DFG300M
DN25
DN25 and DN32
DN40 and DN50
DN25
2
2
2
SEP
1
SEP
SEP
SEP
SEP
SEP
SEP
SEP DFG300MX i) The DFG300A and DFG300M have been specifically designed for use on air, water/ condensate, diathermic oil and /or other fluids which are in Group 2 of the European
Pressure Equipment Directive.
The products’ use on other fluids which are in Group 1 and 2 may be possible but, if this is contemplated, Spirax Sarco should be contacted to confirm the suitability of the product for the application being considered and the request must be stated at the time of order placement.
ii) Check material suitability, pressure and temperature and their maximum and minimum values. If the maximum operating limits of the product are lower than those of the system in which it is being fitted, or if malfunction of the product could result in a dangerous overpressure or overtemperature occurrence, ensure a safety device is included in the system to prevent such over-limit situations.
iii) Determine the correct installation situation and direction of fluid flow. iv) Spirax Sarco products are not intended to withstand external stresses that may be induced by any system to which they are fitted. It is the responsibility of the installer to consider these stresses and take adequate precautions to minimise them.
v) Remove protection covers from all connections and protective film from all name-plates, where appropriate, before installation on steam or other high temperature applications.
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1.2 Access
Ensure safe access and if necessary a safe working platform (suitably guarded) before attempting to work on the product. Arrange suitable lifting gear if required.
1.3 Lighting
Ensure adequate lighting, particularly where detailed or intricate work is required.
1.4 Hazardous liquids or gases in the pipeline
Consider what is in the pipeline or what may have been in the pipeline at some previous time. Consider: flammable materials, substances hazardous to health, extremes of temperature.
1.5 Hazardous environment around the product
Consider: explosion risk areas, lack of oxygen (e.g. tanks, pits), dangerous gases, extremes of temperature, hot surfaces, fire hazard (e.g. during welding), excessive noise, moving machinery.
1.6 The system
Consider the effect on the complete system of the work proposed. Will any proposed action (e.g. closing isolation valves, electrical isolation) put any other part of the system or any personnel at risk?
Dangers might include isolation of vents or protective devices or the rendering ineffective of controls or alarms. Ensure isolation valves are turned on and off in a gradual way to avoid system shocks.
1.7 Pressure systems
Ensure that any pressure is isolated and safely vented to atmospheric pressure.
Consider double isolation (double block and bleed) and the locking or labelling of closed valves. Do not assume that the system has depressurised even when the pressure gauge indicates zero.
1.8 Temperature
Allow time for temperature to normalise after isolation to avoid danger of burns.
1.9 Tools and consumables
Before starting work ensure that you have suitable tools and /or consumables available. Use only genuine Spirax Sarco replacement parts.
1.10 Protective clothing
Consider whether you and / or others in the vicinity require any protective clothing to protect against the hazards of, for example, chemicals, high / low temperature, radiation, noise, falling objects, and dangers to eyes and face.
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1.11 Permits to work
All work must be carried out or be supervised by a suitably competent person.
Installation and operating personnel should be trained in the correct use of the product according to the Installation and Maintenance Instructions.
Where a formal ‘permit to work’ system is in force it must be complied with. Where there is no such system, it is recommended that a responsible person should know what work is going on and, where necessary, arrange to have an assistant whose primary responsibility is safety.
Post ‘warning notices’ if necessary.
1.12 Handling
Manual handling of large and/or heavy products may present a risk of injury. Lifting, pushing, pulling, carrying or supporting a load by bodily force can cause injury particularly to the back. You are advised to assess the risks taking into account the task, the individual, the load and the working environment and use the appropriate handling method depending on the circumstances of the work being done.
1.13 Residual hazards
In normal use the external surface of the product may be very hot. If used at the maximum permitted operating conditions the surface temperature of some products may reach temperatures of 239°C (462°F).
Many products are not self-draining. Take due care when dismantling or removing the product from an installation (refer to ‘Maintenance instructions’).
1.14 Freezing
Provision must be made to protect products which are not self-draining against frost damage in environments where they may be exposed to temperatures below freezing point.
1.15 Disposal
Unless otherwise stated in the Installation and Maintenance Instructions, this product is recyclable and no ecological hazard is anticipated with its disposal providing due care is taken.
1.16 Returning products
Customers and stockists are reminded that under EC Health, Safety and
Environment Law, when returning products to Spirax Sarco they must provide information on any hazards and the precautions to be taken due to contamination residues or mechanical damage which may present a health, safety or environmental risk. This information must be provided in writing including
Health and Safety data sheets relating to any substances identified as hazardous or potentially hazardous.
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2. General product information
2.1 General
The DFG300 is specifically designed for the removal of suspended / deposited solids and water from the bottom of steam boilers. The valve has been designed for spring-to-close on power failure. The manual version can be upgraded to an automatic version.
Available types
DFG300A
DN25, DN32, DN40 and DN50 steel bodied air / water actuated valve supplied with manual actuation lever.
DFG300AX
DN25 stainless steel bodied air / water actuated valve supplied with manual actuation lever.
DFG300M
DN25, DN32, DN40 and DN50 steel bodied manually actuated valve complete with lever (can be automated).
DFG300MX
DN25 stainless steel bodied manually actuated valve complete with lever (can be automated).
When used with a Spirax Sarco blowdown controller the automatic version provides timed control of suspended solids blowdown, ensuring that the recommended blowdown occurs with the minimum of heat loss and avoids duplication and omissions.
The valve can be fitted with a mechanical switchbox. This can be linked to the blowdown controller or a BMS system to indicate when the valve has not closed.
3-way solenoid valve -
A ¼" 3-way solenoid valve is an available option that may be either directly mounted on the actuator or remotely fitted.
Actuator -
The actuator incorporates a rolling diaphragm that ensures a linear operation over the full operating stroke. The actuator can be air or water actuated. The air must, however, be dry and clean. Any other non-corrosive gas can also be used as the operating medium. If water is used, it must be clean, oil and contaminant free and at a temperature of below 70 °C (158°F).
Switch box -
A switch box containing a microswitch can be optionally mounted below the actuator on a bracket, and allows connection to a blowdown controller or a building management system if required. The microswitch is set to indicate whether the valve is 'closed' or not fully closed. Note: it does not indicate that the valve is 'fully open'.
The microswitch is adjustable.
Manual override lever -
A manual override lever is provided with the DFM300 valve.
In some countries (including the UK), regulations state that only one lever is permissible within the boiler house. If more than one DFM300 valve is used additional levers should be removed from the boiler house. When not in use the lever should be removed from the valve and stored in a safe place.
2.2 Sizes and pipe connections
DN25, DN32, DN40 and DN50 flanged EN 1092 PN40.
2.3 Technical data
Solenoid valve
Supply voltage
Protection rating (with connector)
Mechanical switch
Supply voltage
Protection rating (body)
Blowdown timer
Supply voltage controller
Protection rating (housing)
24 Vdc, 24 Vac, 230 Vac or 110 Vac
IP65
600 Vac and 250 Vdc max
IP67
230 Vac or 115 Vac
IP40
2.4 Kvs values
Valve size DN25 DN32 DN40
Seat diameter 25 mm (1") 40 mm (1 ½") 40 mm (1 ½")
Kvs values 17 20 24
For conversion: Cv (UK) = Kv x 0.963 Cv (US) = Kv x 1.156
DN50
40 mm (1 ½")
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IM-P405-38 AB Issue 4
2.5 Pressure / temperature limits
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Pressure psi g
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Steam saturation curve
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Pressure bar g
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The product must not be used in this region.
The product should not be used in this region or beyond its operating range as damage to the internals may occur.
Body design conditions
PMA Maximum allowable pressure 40 bar g @ 120 °C
TMA Maximum allowable temperature 300 °C @ 27.5 bar g
Minimum allowable temperature
PMO Maximum operating pressure
TMO Maximum operating temperature
Ambient operating temperature range
239
-20
0
32 bar g @ 239
°C
°C
°C @ 32 bar g
°C to +90°C
PN40
(580 psi g @ 248 °F)
(572 °F @ 399 psi g)
(32
(464 psi g @ 462
(462
°F)
°F)
°F @ 464 psi g)
(-4 °F to +194°F)
Maximum operating air / water pressure 6 bar g (87 psi g)
Minimum air
Metric
Differential pressure ( P) across the valve
10 bar g
15 bar g
20 bar g
25 bar g
30 bar g
32 bar g pressure 145 psi g
217 psi g
290 psi g
362 psi g Imperial
435 psi g
Maximum temperature for a water actuated valve
464 psi g
70
°C
Designed for a maximum cold hydraulic test pressure of 60 bar g
Minimum air pressure
4 bar g
4.5 bar g
5 bar g
5.5 bar g
6 bar g
6 bar g
58 psi g
65 psi g
72 psi g
80 psi g
87 psi g
87 psi g
(158
°F)
(870 psi g)
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2.6 Materials
No. Part
1
2
3
4
Body
Valve seat
A or M
AX or MX
DN25
Material
Steel
Stainless steel
Stellited stainless steel
Bonnet / yoke
DN32 to DN50 Stainless steel
Actuator housing
Steel
Pressed steel
GP 240 GH
AISI 316
ASTM A479 316
BS 970 431 S29
GP 240 GH
5
6
7
8
9
Valve head
Gland seals
Bottom cover
A or M
AX or MX
Spring guide
Spring
10 Gland follower
11 Stuffing box flange
12 Body nuts
13 Body studs
14 Body gasket
15 Diaphragm
Air / water ¼" BSP
Stellited stainless steel
Graphite rings
Steel
Stainless steel
Steel
Spring steel
Stainless steel
Steel
Steel
Steel
Graphite
Fabric reinforced nitrile rubber
ASTM A479 316
GP 240 GH
AISI 316
Fe 37B
ASTM A479 316
Fe 37B
ASTM A194 2H
ASTM A193 B7
Air / water ¼" BSP
15
Vented plug
4
Vented plug
1
9
11
10
6
8
3
1
2
9
11
10
6
2
12 14 5 7 13
Fig. 1 DFG300A and DFG300AX DN25
8
12 14 5 7 13
Fig. 2 DFG300A DN32 to DN50
IM-P405-38 AB Issue 4
3. Installation
WARNING
Read Section 1, 'Safety information' before attempting any installation.
3.1 General
The valve should preferably be installed with the actuator vertically above the pipework and having the arrow pointing in the direction of flow as indicated on the valve body, but it can also be fitted in other positions, except upside down. Install the valve between matching flanges taking care to ensure correct alignment.
The valve should be installed in such a position as to allow full access to both actuator and valve for maintenance purposes.
WARNING: The actuator housing must only be pressurised on the opposite side of the diaphragm to the springs.
The air / water supply to the solenoid valve / actuator must be in 10 mm ( ") minimum diameter pipe.
The air / water inlet connection
Actuator maximum air pressure
¼" BSP (G)
6 bar g (87 psi g)
3.2 Water actuation
For water actuation a suitable 3-way solenoid valve must be used. We recommend the
Spirax Sarco WAV1 solenoid valve.
Maximum water temperature onto the actuator should be 70 °C (158°F). If water hotter than
70 °C (158°F) is being used a cooling leg / water seal pot should be used.
A suitable water seal pot is the Spirax Sarco WS4.
3.3 Switch box -
optional extra
Refer to Figure 3 for product assembly and proceed as follows:
- Disconnect the air supply from the
pneumatic actuator.
- Loosen and unscrew the locking
grub screw and then the actuator.
- The actuator can now be removed.
- Fit the mounting bracket over the top
of the actuator yoke with the special
tongue pointing vertically downwards,
so that the bracket doesn't move.
- Then install the switch box below the
mounting bracket on the opposite side
of the yoke to the grub screw.
- Refit and fully tighten the actuator.
- Replace and tighten the grub screw.
- The mechanical switch should be
located in such a position as to allow
the correct sliding of the roller on the
upper surface of the fork arm. This
action takes place on the opposite side
of the yoke to the grub screw, towards
the hand lever connection, as shown
in Figure 3.
- Adjust the switch lever stroke so that
vertical movement of the fork causes
the switch to operate.
- Tighten the bracket bolts. Take care to
ensure that the switch roller is correctly
located, so that it slides without any
interference and always remains within
its working line of the fork arm.
- The switch terminal connections are
shown in the Installation and Maintenance
Instructions for the switch box.
Tongue
Locking grub screw
Fork
Hand lever connection
Actuator yoke
Fig. 3 Mechanical switch mounting
Actuator
Mounting bracket
Mechanical switch box
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4. Operation
The frequency of bottom blowdown normally depends upon the boiler operating regime and the boiler manufacturers instructions, as a minimum it is typically done once a day for up to five seconds.
The air / water supply is switched on by the solenoid valve, causing the piston to move against the spring pressure.
The valve spindle (attached to the piston) moves the valve cone away from the seat, opening the valve fully. As the valve is opened, a scraper ring removes any deposits on the valve stem protecting the seals. On release of the air / water pressure, the springs return the valve to the closed position.
The solenoid valve has an override switch, which is pushed in and then turned to lock it, allowing the DFG300A or DFG300AX to be operated independently of an electricity supply.
The manual override lever is pushed downwards to lift the stem and open the valve.
5. Maintenance
WARNING
Read Section 1, ‘Safety information’ before attempting any maintenance work.
Isolate the actuator electrically and pneumatically before any maintenance is carried out.
M6 Actuator bolts
18
8
9
11
10
6
11
10
6
Fig. 4
10
12 14 5 7 13
Fig. 5
IM-P405-38 AB Issue 4
5.1 General
Periodically check that all fasteners remain tight. No routine maintenance is required.
However periodic inspections of all parts are recommended.
5.2 Overhauling the valve
Please refer to Figure 4 for location of parts for the following replacement procedures or fitting of accessories.
1. Actuator – Ensure the actuator is vented and isolated and simply unscrew the actuator (4) from the valve.
2. Actuator diaphragm (15) – Open the actuator by removing the M6 bolts. Ensure the inside of the actuator is clean and apply grease to the operating piston and piston guide.
Replace the diaphragm and the actuator lid and replace and tighten the bolts evenly
(see Table 1 - Recommended tightening torques, page 12).
3. Gland seals (6):
- Remove the actuator (DFG300A and DFG300AX) or the stop nut on top of the manual
version (DFG300M and DFG300MX).
- Remove the lever by unscrewing the bolts attached to the spring guide (8) and the
lever hinge.
- Unscrew the spring guide lock-nut (18).
- Mark the position of the spring guide on the valve spindle. Using a screwdriver inserted
in the slot on top of the spindle to avoid rotation, unscrew the spring guide ( 8).
- Unscrew the 4 x M14 nuts and remove the spring guide, spring, stuffing box flange (11),
gland follower ( 10) and gland seals (6).
- Ensure all parts are clean, in particular the seal locating faces.
- Insert the new gland seals as shown in Figure 5. Reassembly the gland follower and
stuffing box flange taking care that the gland follower is correctly located in the stuffing
box flange.
- Re-assemble the spring and spring guide in the bonnet / yoke assembly.
- Ensure the spindle is clean and lubricated and replace the bonnet gasket. Carefully
assemble the Yoke assembly over the spindle.
- Using the screwdriver to avoid rotation of the spindle tighten the spring guide
until it is at it’s original marked position and lock its position with the lock nut.
- Tighten the 4 x M14 nuts and replace the lever ensuring it is correctly attached to the
spring guide.
- Replace the actuator (DFG300A and DFG300AX) or the stop nut (DFG300M and
DFG300MX).
Warning: Do not operate the lever without the actuator or stop nut reassembled.
4. Replacement of the switchbox:
- Isolate the electrical supply.
- Disconnect the wiring to the switchbox.
- Unscrew the 4 screws that attach the switchbox to the square support bracket.
- Mount and attach the new switchbox.
- Adjust the position of the lever in order to operate the switch at the desired position.
- If further adjustment is required loosen the screws on the support bracket that connects
to the yoke and move the switch box assembly. Tighten the screws when the desired
position is reached.
- Restore the electrical connections and the electrical supply.
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6. Spare parts
Spare parts
The spare parts available are detailed below. No other parts are supplied as spares.
Available spares
Stuffing box packing (3 off)
Actuator diaphragm
Gaskets kit (2 sets)
Mechanical switch (without mounting kit)
Manual actuation lever
6
15
14
How to order spares
Always order spares by using the description given in the column headed 'Available spares' and state the type and size of the valve.
Example: 1 off Actuator diaphragm for a Spirax Sarco DN40 DFG300A automatic boiler blowdown valve.
15 15
6
6
14
Fig. 6 DFG300A and DFG300AX DN25
14
Fig. 7 DFG300A DN32 to DN50
Table 1 Recommended tightening torques
Part
Actuator bolts
Body nuts
Lever hinge nuts
Spring guide
12
10 A/F
22 A/F
17 A/F
10 A/F
mm
M6
M14
M10
M12
N m lbf ft
5 - 6
70
5
25
3.5 - 4.5
51.5
3.5
18.5
IM-P405-38 AB Issue 4
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