DP27, DP27E, DP27R and DP27Y Pilot Operated Pressure Reducing Valves

DP27, DP27E, DP27R and DP27Y Pilot Operated Pressure Reducing Valves
IM-P470-03
4700036/6
CH Issue 6
DP27, DP27E, DP27R and DP27Y
Pilot Operated Pressure Reducing Valves
Installation and Maintenance Instructions
1.Safety information
2.General
product information
3.Installation
4.Commissioning
5.Maintenance
6.Spare parts
7.Fault finding
IM-P470-03 CH Issue 6
© Copyright 2012
1
Printed in the UK
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.
The products fall within the following Pressure Equipment Directive categories:
Group 2
ProductGases
DN15 - DN40
SEP
DP27 and all derivatives
DN50
1
i) The products have been specifically designed for use on steam, air and inert
industrial gases which are in Group 2 of the above mentioned Pressure Equipment
Directive. The products’ use on other fluids 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.
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.
1.2Access
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.
1.3Lighting
Ensure adequate lighting, particularly where detailed or intricate work is required.
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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.
1.8Temperature
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.
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.
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1.12Handling
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 300°C.
Many products are not self-draining. Take due care when dismantling or removing the
product from an installation (refer to 'Maintenance instructions').
1.14Freezing
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.
1.15Disposal
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. However, if the valve has any PTFE components,
special care must be taken to avoid potential health hazards associated with
decomposition/burning of this material.
PTFE:
- Can only be disposed of by approved methods, not inceration.
- Keep PTFE waste in a separate container, do not mix it with other rubbish, and
consign it to a landfill site.
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IM-P470-03 CH Issue 6
2. General product information
2.1 General description
These instructions apply to the DP27 and most derivatives including the DP27E, DP27R
and DP27Y.
The instructions primarily relate to the use of the DP27 on steam but can be used as a
guide when the valve is used on compressed air.
Note: For additional information see the relevant Technical Information Sheets.
2.2 Sizes and pipe connections
Screwed BSP (BS 21 parallel) or NPT (DN15, DN20 and DN25 only).
Flanged DN15LC - Low Capacity version, DN15, DN20, DN25, DN32, DN40 and DN50.
DN15 - DN50 EN 1092 PN16 and PN25
Standard flanges:
DN25 - DN50 BS 10 Table H and ASME 300
DN15 - DN50 JIS 10 / 16 and ASME 150 Flanges available
DN15 - DN20 BS 10 Table F on request:
DN15 ASME 300
IM-P470-03 CH Issue 6
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DP27E
Temperature °C
DP27,
DP27R
and
DP27Y
Temperature °C
2.3 Pressure / temperature limits
A
D
B
Steam
saturation
curve
Pressure bar g
G
Steam
saturation
curve
E
C
G
Pressure bar g
The product must not be used in this region.
The product should not be used in this region as damage to the internals may occur.
A-D-E Screwed and flanged EN 1092 PN25, ASME 300, and BS 10 Table H.
A-B-C Flanged ASME 150.
G-GThe DP27E is limited to 10 bar and 190°C.
Note: DP27 has a variable rate conical pressure adjustable spring fitted providing a
downstream pressure range of 0.2 - 17 bar g.
DP27Y has a pressure spring with a range of 0.2 - 3 bar g.
DP27R Maximum downstream reduced pressure 15 bar g. The control pressure
signal to the pilot diaphragm must be approximately 0.7 bar above the required
reduced downstream pressure.
Body design conditions Maximum design pressure
Maximum design temperature
Minimum design temperature
DP27, DP27R, DP27Y
Maximum upstream pressure
for saturated steam service DP27E
DP27, DP27R, DP27Y
Maximum operating temperature
DP27E
Minimum operating temperature
Note: For lower operating temperatures consult Spirax Sarco.
Maximum differential pressure is limited to the PMO
Designed for a maximum cold hydraulic test pressure of: Note: With internals fitted, test pressure must not exceed: 6
PN25
25 bar g @ 120°C
232°C @ 21 bar g
-10°C
17 bar g
10 bar g
232°C
190°C
0°C
38 bar g
25 bar g
IM-P470-03 CH Issue 6
3. Installation
Note: Before actioning any maintenance programme for the pilot operated
pressure reducing valve (PRV) observe the 'Safety information' in Section 1.
Referring to these Installation and Maintenance Instructions,
name-plate and Technical Information Sheet, check that the product
is suitable for the intended installation.
3.1 Supply
DP27 (Figure 1)
These are supplied ready for fitting and have a variable rate conical pressure spring suitable
for a downstream pressure of 0.2 - 17 bar.
DP27Y (Figure 1)
The DP27Y is supplied as the DP27, but has a lower rate pressure adjustment spring for
a downstream pressure range of 0.2 - 3 bar.
Pressure setting adjustment screw
Lock-nut
Pressure adjustment spring
Recommended downstream pressure
balance pipe connection
(refer to Section 3.8, page 12)
Downstream internal
pressure balance pipe
Fig. 1 DP27 and DP27Y
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DP27E
The DP27E (Figure 2) is supplied as for the DP27 with a control spring but the maximum
pressure is limited to 10 bar g due to the addition of the solenoid valve. A solenoid operated
valve is fitted in the pipe between the pilot valve and the main diaphragm chamber and is
thus in series with the normal pilot valve.
The purpose of the solenoid valve is to override the pilot valve thus causing the main valve
to shut-off. It can be controlled by any device capable of interrupting the supply of current
to the solenoid coil.
The solenoid is arranged to open the valve when the coil is energised so that whatever
switching device is used it must be arranged to break the current to close the main valve. In
this way the unit will always 'fail-safe' i.e. will close the main valve in the event of a failure
in electrical supply.
Note: A special pilot valve assembly is used in the 'E' version to prevent leakage past the
pilot valve plunger when the solenoid is used to close the valve.
Electrical supply
It is important that the solenoid is connected to the correct voltage. Therefore always
check on the supply details which are stamped on the solenoid valve name-plate before
attempting to connect up.
Electrical connection is by cable plug to DIN 43650. All wiring, connectors, etc. in close
proximity to the valve should be of heat resisting type and comply with local and national
electrical codes.
Earth
The solenoid valve should be adequately earthed.
Solenoid valve
Fig. 2 DP27E
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DP27R
The DP27R (Figure 3) is supplied ready for fitting. Downstream pressure can be adjusted
remotely by a controlled air supply to the pilot diaphragm chamber. The actuating air supply
must be at a pressure approximately 0.7 bar g above the required downstream
pressure and controlled through a metal bodied self-relieving regulator. A check valve should
be fitted to prevent steam entering the air system, in the unlikely event of a failure of the
pilot diaphragm. Any filter should be fitted with a metal bowl and should preferably be on
the upstream side of the check valve.
The actuating air supply controlled by the regulator should be connected to the union
fitting attached to the air control block as shown in Figure 4. The air inlet connection is
suitable for 6 mm O/D copper tube. The maximum reduced pressure available through the
DP27R is 15 bar g. Typical installation is shown in Figure 9, page 15.
Fig. 3 DP27R
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3.2Fitting (Figures. 4, 5 and 6)
The valve should always be fitted in a horizontal pipeline with the main diaphragm
chamber below the line (Figure 4). To meet high capacities or widely varying loads, or
where stand-by facility is required, two or more valves may be used in parallel (Figure 5).
For pressure turndown in excess of 10 to 1 consideration should be given to using the two
valves in series. To avoid instability pipework volume between the valves should be equivalent
to at least 50 pipe diameters in length of the intermediate correctly sized pipework. To
ensure adequate drainage of the space between the two reducing valves a trap set should
be fitted as shown in Figure 6.
Strainer with
100 mesh stainless
steel screen
Separator
Pressure
sensing
pipe
Pressure
reducing
valve
Steam
supply
Spiratec
sensor
chamber
Strainer
Safety
valve
Discharge
pipe
Small bore
drain
0.9 m or
15 pipe diameters clear
on either side
See Section 3.6, page 11.
Check
valve
Downstream isolating valve to
provide no-load conditions for
setting pressure reducing valve
Float type
steam trap
DP27 and DP27E
Float type
steam trap
Alternative for
draining
separator
Steam supply
Strainer
Check
valve
Sight
glass
Separator
Compressed
air
Compressed
air
Regulator
Filter
DP27R
Fig. 4 Recommended installation
10
Installation for
compressed air
Compressed
air trap
IM-P470-03 CH Issue 6
­Q
Steam
supply
­Q
­Q See Section 3.6
Fig. 5 Two pressure reducing valves in parallel
3.3 Pipeline sizing
The piping on both sides of the valve must be sized so that velocities do not exceed 30 m / s.
This means that a properly sized valve will often be smaller than the connecting
pipework.
3.4 Pipeline stresses
Line stresses caused by expansion or inadequate support should not be imposed on the
valve body.
3.5 Isolating valves
These should preferably be of the full bore type.
3.6 Removal of condensate
It is recommended that a separator with trap set is fitted upstream of the valve to ensure
dry steam conditions.
If there is a rise in the low pressure line from the valve then a further drain point should
be provided to keep the valve drained after shutdown.
Steam supply
Separator
­Q
­Q See Section 3.6
Trap set
Trap set
Fig. 6 Two pressure reducing valves installed in series
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3.7 Protection from dirt
The valve should be protected by a pipeline strainer with 100 mesh screen. The strainer
should be fitted on its side to prevent the accumulation of water. The strainer screen should
be examined and cleaned at regular intervals.
3.8 Pressure sensing
For applications that require closer control, improved stability or maximum capacity condition
the internal balance pipe should be replaced by an external pressure sensing pipe
(supplied by others) as follows:
Remove the internal balance pipe assembly.
The resulting " BSP tapping in the side of the body should be blanked using the plug provided
in the linen bag attached to the valve (which also contains the fitting instructions). The other
" BSP tapping in the side of the pilot valve chamber, should be used to fit the external
pressure sensing pipe. This is suitable for the fitting of 6 mm O/D pipe. If suitable pipe is not
available the compression fitting can be removed and ¼" nominal bore steel pipe screwed
directly into the pilot valve chamber.
The pressure sensing pipe should be connected into the top of the reduced pressure main
at a point where in either direction there is a length of straight pipe uninterrupted by fittings
for at least 1 m or 15 pipe diameters whichever is the greater. It should be arranged with a
positive fall so that any condensate can drain away from the DP27. Where the size of the
reduced pressure main makes it difficult to maintain a fall when entering the top of the main,
the pressure sensing pipe may be connected in the side of the main.
3.9 Pressure gauges
It is essential to fit a pressure gauge on the upstream and downstream side so that the
valve can be properly set and monitored.
3.10 Continuous duty
For continuous duty applications where a constant steam supply is essential then a parallel
stand-by PRV station is recommended to allow for planned maintenance, see Figure 5,
page 11. Alternatively a bypass line can be used (see Figures 8 and 9, page 15). It is important
that the bypass should have a similar capacity to the pressure reducing valve which is achieved
by choosing an appropriately sized valve or by using a reduced orifice in the line.
The handwheel should be padlocked to prevent unauthorised use, and when in use should
be under constant manual supervision.
The bypass may be arranged above or to the side of the main assembly but never below it.
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3.11 Safety valve
A safety valve should be fitted to protect the downstream equipment from excessive
pressure. It should be set to lift below the safe working pressure of the downstream equipment,
and will normally be sized to pass the full capacity of the PRV should the PRV fail in the fully
open position. The safety valve set pressure should take account of its reseat characteristic
and the 'No-load' pressure setting of the PRV. For example, the typical blowdown value
(reseat differential) for a DIN type safety valve is 10% of set pressure. The minimum possible
safety valve set pressure must therefore equal the no-load set pressure of the reducing valve
plus the blowdown value of the safety valve plus a small margin of at least 0.1 bar. If the safety
valve lifts and the working pressure is too close then it will not be able to close properly and
will simmer, creating a leak which is often wrongly diagnosed as a result of a leaking reducing
valve.
Discharge pipework should be taken to a safe place.
3.12 Position in relation to other control valves
A
DP27
B
A
C
D
Fig. 7 DP27 position in relation to other control equipment
Line or system isolation valves (A), either remotely actuated or manual, should be installed on
the upstream side of the DP27 reducing valve.
Where there is downstream control equipment (B), particularly when it is fast acting (for
instance pulsed piston actuated valves) ensure the control equipment is at least 50 pipe
diameters away from the DP27 to prevent pressure pulses being transmitted back causing
unstable operation and premature wear or if this is impractical an intermediate vessel can
provide a similar benefit.
Where a safety valve (C) is required to protect the system downstream of a DP27 and where
a control valve is also being used downstream of the DP27, it is recommended that the safety
valve is fitted downstream of the control valve rather than in between the DP27 and the control
valve. If any slight leakage occurs this will avoid any pressure build-up causing nuisance
operation of the safety valve but provide complete protection for the downstream system.
Where valves are installed downstream of the DP27 (B) the intermediate downstream
pipework must be properly trapped (D) to ensure no condensate can build up on the downstream
side of the DP27.
IM-P470-03 CH Issue 6
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4. Commissioning
4.1 Setting procedure (Figure 8 and Figure 9)
1. Ensure that all connections are properly made and that all valves are closed.
DP27, DP27E and DP27Y (Figure 8)
DP27R (Figure 9)
2. Close all valves at reducing valve station, 2. Close all valves at reducing valve station,
including valves on bypass line if fitted.
including the valve on the bypass line, if fitted.
3. Check that adjustment screw is turned
fully anticlockwise until spring is slack.
3. Check that the actuating air supply is off
and the pressure is zero.
4. Check that the pressure gauge isolating cocks are open.
5. For correct operation of the valve it is important that the pilot and main
valves are not subjected to dirt or other hard particles. Therefore, prior
to bringing the valve into operation, ensure that the upstream pipework
has been cleared of all loose dirt and hard particles and that the main
strainer screen is examined and cleaned if necessary.
6. Slowly open the upstream isolating valve until it is fully open.
DP27, DP27E and DP27Y
DP27R
7. Using a 19 mm A/F spanner slowly turn
adjustment screw in a clockwise direction
until desired downstream pressure reading
is obtained.
7. S lowly admit actuating air through the
pressure regulator until the desired
downstream pressure is obtained.
8. Holding the adjustment screw in position
with the spanner tighten down the lock-nut
to secure the setting of the adjustment
spring.
Note
To facilitate resetting of the reducing valve it
may be desirable to position the downstream
pressure gauge at a viewpoint close to the
air regulator.
If this necessitates fitting the pressure gauge
below the steam line, the interconnecting
pipe should be drained at the low point
otherwise the gauge will give a false reading.
9. Slowly open the downstream valve until it is fully open.
Note: After installation or maintenance ensure that thet system is fully functional. Carry
out tests on any alarms or protective devices. It is recommended that after commissioning
the pilot filter is changed and the spare one supplied with the valve is fitted.
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IM-P470-03 CH Issue 6
4.2 Two or more valves in parallel
When more than one reducing valve is used it is an advantage to use two valves of unequal
size, the smaller one being chosen to meet the lower load requirements and the larger valve
to come into operation so that both meet the normal and maximum demand.
It is necessary to commission each valve independently (one at a time) following the procedure
detailed in Section 4.1 but setting the smaller valve at a pressure higher than the larger valve.
2
Optional bypass line (see Section 3.10)
3
2, 6
4
4
Steam flow
5
2, 9
­Q
5
Condensate
return
­Q See Section 3.6, page 11
Fig. 8 Setting procedure sequence DP27, DP27E and DP27Y
2
Optional bypass line (see Section 3.10)
2, 6
Steam flow
4
4
3, 7, 8
5
2, 9
­Q
5
Condensate
return
­Q See Section 3.6, page 11
Fig. 9 Setting procedure sequence DP27R
IM-P470-03 CH Issue 6
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5. Maintenance
Note: Before actioning any maintenance programme observe
the 'Safety information' in Section 1.
Warning:
The body gasket (all DP27 derivatives) and actuating chamber gasket (DP27R)
contains a thin stainless steel support ring which may cause physical injury
if not handled and disposed of correctly.
5.1 Routine maintenance
It is recommended that the valve is dismantled once every twelve to eighteen months for a
complete overhaul and ideally this should be carried out with the valve removed from the line.
The following parts should be inspected and refurbished or replaced as necessary:
- Main valve seat and valve head.
- Pilot valve assembly.
- Pilot filter element.
- Internal strainer screen.
- Main diaphragms.
- Pilot diaphragms.
Pilot valve assembly
Pilot diaphragms
Pilot filter element
Body gasket
Internal strainer screen
Main valve seat
and valve head
Main diaphragms
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IM-P470-03 CH Issue 6
5.2 How to renew the pilot filter element
1. Isolate the reducing valve and zero the pressure.
Filter
2. Unscrew the filter cap and carefully withdraw the filter
element
element.
3. Replace the element and tighten the filter cap to
90 - 100 N m.
Note: The gasket is re-usable.
Filter cap
5.3 How to renew or change the
pressure adjustment spring
2
1
Isolate the reducing valve and zero the pressure in order to
change the pressure adjustment spring.
1. Release the adjustment lock-nut.
2. Turn the adjustment screw anticlockwise. Ensure there
is no compression on the pressure adjustment spring.
3. Undo the 4 off spring housing securing nuts and remove
the spring housing.
3, 6
4. Remove the pressure adjustment spring and the top
spring plate.
5. Reassemble in reverse order.
4
5.4 How to renew the pilot valve assembly
6. DP27, DP27E and DP27Y
Isolate the reducing valve and zero the pressure and proceed to unscrew the 4 off spring
housing securing nuts and remove spring housing, bottom spring plate and diaphragms.
DP27R
Isolate the actuating air supply and zero the pressure and proceed to unscrew the 4 off
actuating chamber nuts and remove the air control block and diaphragms.
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7. Unscrew and remove the pilot valve assembly (19 mm A/F). The pilot assembly has
an integral PTFE seal.
The following handling precautions should be observed.
Handling precautions for PTFE
Within its working temperature range PTFE is a completely inert material, but when heated
to its sintering temperature it gives rise to gaseous decomposition products or fumes which
can produce unpleasant effects if inhaled. Fumes can be produced during processing: for
example, when the material is heated to sinter it, or when brazed connections are being
made to cable insulated PTFE. The inhalation of these fumes is easily prevented by
applying local exhaust ventilation to atmosphere as near to their source as possible.
Smoking should be prohibited in workshops where PTFE is handled because tobacco
contaminated with PTFE will during burning give rise to polymer fumes. It is therefore
important to avoid contamination of clothing, especially the pockets, with PTFE and to
maintain a reasonable standard or personal cleanliness by washing hands and removing
any PTFE particles lodged under the fingernails.
8. Apply superlube grease to the threads before screwing the new pilot valve into the housing.
Torque 45 - 50 N m.
9. Check that there is a very slight clearance between the top of the plunger and a straight
edge placed across the diaphragm location recess.
Straight edge
9
10. Refit the two diaphragms making sure that they are fitted the same way round as they
were removed and that all contact faces are clean. Diaphragms showing signs of wear or
damage should be replaced.
11. DP27, DP27E and DP27Y
Replace the bottom spring plate.
12. DP27, DP27E and DP27Y
Assemble the spring housing and tighten the nuts to the recommended torques
shown in Table 1.
DP27R
Assemble the air control block and tighten the nuts to the recommended torques
shown in Table 1.
Bring the valve back into commission, following as many Steps as necessary in Section 4,
page 14.
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11
10
7
8
Table 1
Recommended tightening torques for spring
housing/actuating chamber cover securing studs and nuts
Size of valve
DN15, DN20, DN25 and DN32
DN40 and DN50
IM-P470-03 CH Issue 6
Nut size
M10
M12
Tightening torques
40 - 50 N m
45 - 55 N m
19
5.5 How to clean or replace the internal strainer screen
DP27, DP27E and DP27Y
Isolate the reducing valve and zero the pressure.
DP27R
Isolate the actuating air supply and zero the pressure.
13. Unscrew the unions and release the pipework.
14. Unscrew the nuts.
15. DP27, DP27E and DP27Y
Remove the pilot valve housing; complete with spring housing assembly.
DP27R
Remove the pilot valve housing, complete with air control block.
16. Remove the internal strainer screen and clean or replace.
17. Ensure the gasket faces are clean.
18. Check that the main valve return spring is in position.
19. Fit a new gasket.
20. Replace the internal strainer screen.
21. DP27, DP27E and DP27Y
Assemble the pilot valve housing complete with spring housing assembly and tighten
the nuts to the recommended torques shown in Table 1, page 19.
DP27R
Assemble the pilot valve housing complete with air control block and tighten the nuts
to the recommended torques shown in Table 1, page 19.
22. Refit the pipework and retighten unions to ensure a tight seal.
Bring the valve back into commission, following as many steps as necessary in Section 4,
page 14.
14
14
21
15
13
16
13
17
17
20
20
22
19
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5.6 How to renew the pilot valve diaphragms
DP27, DP27E and DP27Y
Isolate the reducing valve and zero the pressure.
DP27R
Isolate the actuating air supply and zero the pressure.
23. DP27, DP27E and DP27Y
Unscrew the nuts and remove: spring housing, bottom spring plate and old diaphragms.
DP27R
Unscrew the nuts and remove the air control block and old diaphragms.
24. Ensure that all contact faces are cleaned. New diaphragms should be fitted such that the
precoated sealant (which is only applied to one diaphragm) faces down contacting the
sealing face of the diaphragm chamber.
25. DP27, DP27E and DP27Y
Replace the bottom spring plate.
26. DP27, DP27E and DP27Y
Assemble the spring housing and tighten the nuts to the recomended torque shown in
Table 1, page 19.
DP27R
Assemble the air control block and tighten the nuts to the recommended torques shown
in Table 1, page 19.
Bring the valve back into commission, following as many Steps as necessary in Section 4,
page 14.
23
27
26
28
25
24
30
5.7 How to renew or clean main diaphragms
Isolate the reducing valve and zero the pressure.
29
27. Undo the long union nut and pull away.
28. Undo the M12 nuts and bolts.
29. Drop away the lower diaphragm chamber, the two diaphragms, diaphragm plate and
the pushrod assembly.
30. Thoroughly clean the lower diaphragm chamber making sure contact faces are clean.
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31. Replace the diaphragm plate and pushrod assembly and loosely fit the lower diaphragm
chamber on two bolts either side of the union connection to locate the spigot in the recess.
32. Bring the two new diaphragms together (where precoated sealant is applied this should
face outwards) and slide into position.
If the diaphragms are not renewed, but cleaned only, care must be taken to replace
the diaphragms in their original order.
33. Push the lower diaphragm chamber home to locate in the recess and refit the M12 nuts
and bolts. Progressively and evenly tighten to a torque of 80 - 100 N m.
34. Retighten the long union nut to ensure a steam tight seal.
Bring the valve back into commission, following as many Steps as necessary in Section 4,
page 14.
32
37
31
36
35
33
35
34
5.8 How to service or renew the main valve and seat
DP27, DP27E and DP27Y
Isolate the reducing valve and zero the pressure.
DP27R
Isolate the actuating air supply and zero the pressure.
35. Unscrew the unions and release the pipework.
36. Unscrew the nuts.
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IM-P470-03 CH Issue 6
37. DP27, DP27E and DP27Y
Remove the pilot valve housing, complete with spring housing assembly.
DP27R
Remove the pilot valve housing, complete with air control block.
38. Remove the main valve plus internal strainer screen and clean.
39. Remove the main valve spring and the main valve head. Clean to remove dirt or scale
as necessary.
40. Remove the main valve seat. Clean and remove dirt and scale as necessary.
Note: Examine the faces of the main valve head and seat. If they are only slightly worn
they may be lapped on a flat plate using a fine grinding paste. If either is badly worn or
unfit for further use they must be replaced.
41. Refit the valve seat applying jointing compound to the seating faces and tighten to the
recommended torque shown in Table 2, page 24.
Where a new part has been fitted it will be necessary to reset the main valve pushrod
to give the correct valve lift.
To do this it is necessary to expose the main diaphragm plate and pushrod assembly.
42. Undo the long nuts and pull away.
43. Undo the M12 nuts and bolts.
44. Drop away the lower diaphragm chamber, the two diaphragms, diaphragm plate and
pushrod assembly.
38, 39
41
42
43
40
44
IM-P470-03 CH Issue 6
23
Table 2 Recommended tightening torques for main valve seat
Size of valve
DN15 and DN15 LC
DN20 DN25 DN32
DN40
DN50
Width across flats
30 mm A / F (External)
36 mm A / F (External)
19 mm A / F (Inside)
24 mm A / F (Inside)
30 mm A / F (Inside)
41 mm A / F (Inside)
Tightening torques
110 - 120 N m
140 - 150 N m
230 - 250 N m
300 - 330 N m
450 - 490 N m
620 - 680 N m
45. Refit the pushrod assembly.
46. Refit the main valve head, make sure valve locates on seat.
47. Check the valve lift shown in Table 3 using a depth gauge and adjust if necessary by
screwing the pushrod in or out of the diaphragm plate.
Depth gauge
46
47
50
48
45
Table 3
Size of valve
DN15LC DN15 DN20 DN25 DN32 DN40 DN50 24
49
47
Valve lift
2.5 mm
2.5 mm
2.5 mm
3.0 mm
3.5 mm
4.5 mm
5.0 mm
IM-P470-03 CH Issue 6
48. Thoroughly clean the lower diaphragm chamber making sure contact faces are clean.
49. Replace the diaphragm plate and pushrod assembly and loosely fit the lower diaphragm
chamber on two bolts either side of the union connection to locate the spigot in the recess.
50. Refit the diaphragms in exactly the same way as when they were dismantled.
51. Push the lower diaphragm chamber home to locate in the recess and refit the M12 nuts
and bolts. Progressively and evenly tighten to a torque of 80 - 100 N m.
52. Retighten the long union nut to ensure a steam tight seal.
51
52
57 
58
55
58
54
56
53
53. Refit the main valve head.
54. Replace the main valve return spring.
55. Fit a new gasket.
56. Replace the internal strainer screen.
57. DP27, DP27E and DP27Y
Assemble the pilot valve housing complete with spring housing assembly and tighten
the nuts to the recommended torques shown in Table 1, page 19.
DP27R
Assemble the pilot valve housing complete with air control block and tighten the
nuts to the recommended torques shown in Table 1, page 19.
58. Refit the pipework and retighten the unions to ensure a tight seal.
Bring the valve back into commission, following as many Steps as necessary in Section 4,
page 14.
IM-P470-03 CH Issue 6
25
5.9 How to service or renew the solenoid valve
DP27E
Depressurize the valve and turn off the electrical power supply.
59. Undo the retaining nut and slip the entire solenoid enclosure off the solenoid base and
sub-assembly or plugnut / core tube sub-assembly.
60. Unscrew the bonnet or solenoid base sub-assembly and remove the core spring, core
assembly and body gasket.
All parts are now accessible for cleaning replacement. Replace worn or damaged parts
with a complete Spare parts kit (item 'W', pages 28 and 29) for best results.
61. Reassemble in reverse order paying careful attention to exploded views provided.
62
59, 63
61
60
CAUTION
The solenoid must be fully reassembled as the housing
is part of, and completes the magnetic circuit.
5.10 Coil replacement
Switch off the electrical power supply and disconnect the coil lead wires.
62. Undo the retaining nut.
63. Slip the washer, insulating washers and coil off the solenoid base sub-assembly.
Reassemble in reverse order (see CAUTION above).
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IM-P470-03 CH Issue 6
6. Spare parts
Interchangeability of spares
The following table shows how in certain sizes some parts are interchangeable. For example
in the line headed 'Main diaphragm' the diaphragm used in the screwed valves ½" and ¾" is
common to these sizes by the letter 'a', the letter 'c' indicates that one diaphragm is common to
the DN40 and DN50 valves. All spares are interchangeable with the DP27T and where marked
† are interchangeable with the 37D temperature control.
†
†
†
†
†
†
Screwed
Flanged
Size DN ½"LC ½" ¾" 1" 15LC 15 20 25 32 40 50
Maintenance kit
a aab f f a bc de
Main diaphragm
a aab a a a bb cc
Pilot diaphragms
a aaa a a a aa aa
Pilot valve assembly
a aaa a a a aa bb
Pilot filter element
a aaa a a a aa aa
Main valve assembly
a b cd a b c d e f g
Internal strainer screen
a aab f f a bc de
Main valve return spring
a aaa a a a aa cc
Pressure adjustment spring
a aaa a a a aa aa
Control pipe assembly
a aab f f a bc de
Balance pipe assembly
a aab f f a bc de
Body gasket
a aaa a a a aa bb
Set of spring housing
a aaa a a a aa bb
securing studs and nuts
† Set of main body studs and nuts
† Set of diaphragm
securing bolts and nuts
Pushrod and main diaphragm
plate assembly
IM-P470-03 CH Issue 6
a aaa a a a aa bb
a aaa a a a aa bb
a aab a a a bb cc
27
Spare parts
The spare parts available are shown in solid outline. Parts drawn in broken line are not
available as spares.
Available spares
Maintenance kit
A stand-by set of spares for general maintenance purposes and covers all spares marked *
A
* Main diaphragm (2 off)
* Pilot diaphragm (2 off)
B
C or C1
* Pilot valve assembly
Pilot valve filter element and gasket (3 pieces)
E, F
K, L
Main valve assembly
M
* Internal strainer screen
* Main valve return spring
N
Pressure adjustment spring DP27 and DP27E
(Not required for DP27R)DP27Y
Control pipe assembly
0.2 to 17 bar
0.2 to 3 bar
O
P
* Downstream pressure balance pipe assembly (internal pressure sensing pipe)Q
R
* Body gasket (3 off) Pilot valve block gasket (DP27R only)
R1
Set of spring housing / actuating chamber cover securing studs and nuts (set of 4) S
Set of main body studs and nuts (set of 4)
Set of diaphragm securing bolts and nuts Valve sizes
Pushrod and main diaphragm plate assembly
DN15 - DN32 (set of 10)
DN40 and DN50 (set of 12)
T
V
Y
Type DP27E only
Solenoid valve complete
W
Replacement coil
X1
Valve seat and core assembly
X2
How to order spares
Always order spares by using the description given in the column headed 'Available spares'
and state the size and type of the pressure reducing valve.
Example:
1 - Main valve assembly for a Spirax Sarco DN25 DP27 pilot operated pressure reducing valve.
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IM-P470-03 CH Issue 6
DP27E
W
X2
Solenoid valve complete
X1
S
S
R1
O
C
DP27R
or
B
P
F
Main valve assembly
E
N
K
L
DP27,
DP27R
and
DP27Y
R
V
C1
S
R
DP27E
Q
T
T
Y
M
A
V
IM-P470-03 CH Issue 6
29
7. Fault finding
7.1 Preliminary procedure
Before undertaking the following fault finding procedure, ensure the valve has been isolated
and that upstream and downstream pressures are zero. Possible fault checks are given in a
logical order below.
7.2 Downstream pressure zero or too low
If downstream pressure drops below set pressure or is zero check the following:
1. No high pressure steam reaching the reducing valve. Check that steam is turned on and
that the strainer is clear. (To assist with commissioning and fault finding it is recommended
to fit an upstream pressure gauge).
2. Pressure adjustment spring broken.
3. Pipe assembly (Item 'P' on page 29) blocked. Remove by uncoupling union nuts and
blow through to clear obstruction.
4. Control orifice blocked. Unscrew from outlet port and clear out obstruction. For identification
this coupling has a groove around the hex.
5. Main diaphragms fractured. Replace diaphragms following Steps 27 to 34, Section 5.7.
6. Pilot valve plunger too short. Check as Section 5.4, Step 9.
7. Valve capacity insufficient for downstream conditions.
a) Check that the upstream pressure is correct. If it is low, the capacity of the valve will
be reduced.
b) Ensure that the pressure sensing pipe is fitted as recommended in Section 3.8 and if
necessary fit an external pressure sensing pipe as described. If the downstream
pressure is still too low, then a larger valve with more capacity is required.
7.3 Downstream pressure too high
If the pressure on the downstream side of the reducing valve has risen above the required
set pressure check the following:
1. Downstream pressure sensing pipe blocked. Dismantle and blow through.
2. Control orifice (item 'P1' on page 29) blocked. Unscrew pipework from side of body and
clean out. For identification this coupling has a groove around the hex.
3. Pilot valve diaphragms fractured. Check and replace (see Section 5.6, page 21).
4. Pilot valve or pilot valve plunger is sticking. Follow Steps 6 to 9, Section 5.4. Check as
Section 5.4, Steps 6 to 12
5. Main valve not seating. Check and replace (see Section 5.8).
6. Main valve pushrod sticking. Follow Steps 27 to 34, Section 5.7.
7. Pilot valve plunger too long. Check as Section 5.4, Step 9.
8. Pilot valve not seating. Check as Section 5.4, Steps 6 to 12.
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IM-P470-03 CH Issue 6
7.4 Hunting
Hunting may coincide with variations in steam load. If this is the case, the following checks
should be made before dismantling the valve:
1. Check that the upstream pressure is stable. If the pressure drops during full-load conditions,
it is possible that there is a partial blockage upstream, or that the upstream pipework is
undersized. If the upstream pressure is low, the effect will be to reduce the capacity of the
valve with the possibility of not maintaining the downstream pressure during full-load
conditions.
2. If the upstream pressure is correct, and stable, set the valve on dead-end conditions.
Apply full-load to the valve.
If the downstream pressure drops excessively during full-load condition, it is likely that the
valve is undersized, in which case it should be replaced.
Once it has been determined that the upstream pressure is correct and stable, and that
the valve is correctly sized, the following check should be carried out on the valve:
3. Steam is very wet. Ensure the valve installation is as recommended in Figure 4, page 10.
4. The point at which the external pressure sensing pipe is tapped into the main is in a
turbulent area. Refer to Section 3.8 for guidance.
5. Loose dirt in pipe assembly (Item 'P' on page 29). Remove pipe assembly. Blow through
to clear.
6. Pilot valve or pilot valve plunger is sticking. Follow Steps 6 to 9, Section 5.4.
7. Main valve pushrod sticking. Follow Steps 27 to 34, Section 5.7.
8. Pilot diaphragms or main diaphragms overstretched. To replace, see Section 5.6, page 21.
IM-P470-03 CH Issue 6
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IM-P470-03 CH Issue 6
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