Spirax Sarco DP27S User manual

IM-IBR16-27IN Issue 6 1
1. Safety information
2. General
product information
3. Installation
4. Commissioning
5. Maintenance
6. Spare parts
7.Faultnding
© Copyright 2016
Printed in India
DP27S and DP27SY
Pilot Operated Pressure Reducing Valves
Installation and Maintenance Instructions
IM-IBR16-27IN
Issue 6

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1. Safety information
Safe operation of these products can only be guaranteed if they are properly
installed, commissioned, used and maintained by qualied 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 Indian Boiler
Regulations, 1950.
i) The products have been specically designed for use on steam and air. The
product s’ use on oth er ui d s m ay be possible but, if this is contem p lated, Spirax
Sarco should be contacted to conrm the suitability of the product for the
application being considered.
i i ) C h e c k m a t e r i a l s u i t a b i l i t y , p r e s s u r e a n d t e m p e r a t u r e a n d t h e i r m a x i m u m a n d
m i n i m u m v a l u e s . I f t h e m a x i m u m o p e r a t i n g l i m i t s o f t h e p r o d u c t a r e l o w e r t h a n
those of the system in which it is being tted, 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 uid ow.
iv) Spirax Sarco products are not intended to withstand external stresses that may
be induced by any system to which they are tted. 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 lm from all
name-plates, where appropriate, before installation on steam or other high
temperature applications.
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
p r e v i o u s t i m e . C o n s i d e r :  a m m a b l e m a t e r i a l s , s u b s t a n c e s h a z a r d o u s t o h e a l t h ,
extremes of temperature.

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1.5 Hazardous environment around the product
Consider: explosion risk areas, lack of oxygen (e.g. tanks, pits), dangerous gases,
e x t r e m e s o f t e m p e r a t u r e , h o t s u r f a c e s ,  r e h a z a r d ( e . g . d u r i n g w e l d i n g ) , e x c e s s i v e
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.
C o n s i d e r d o u b l e i s o l a t i o n ( d o u b l e b l o c k a n d b l e e d ) a n d t h e l o c k i n g o r l a b e l l i n g
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.
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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1.12 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 232°C.
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. 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 landll site.

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2.2 Sizes and pipe connections
Screwed BSP or NPT (DN15, DN20 and DN25 only).
Flanged DN15LC - Low Capacity version, DN15, DN20, DN25, DN32, DN40 and DN50.
DN15 - DN50 ASME 150
Standard flanges: DN15 ASME 300
DN25 - DN50 ASME 300
2. General product information
2.1 General description
These instructions apply to the DP27S and the derivative DP27SY.
The instructions primarily relate to the use of the DP27S 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.

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2.3 Pressure / temperature limits
The product must not be used in this region.
For optimum performance, the maximum design pressure should not exceed 17.2 bar g
A-D-C Screwed and flanged ASME 300
A-B-C Flanged ASME 150.
Note: DP27S has a variable rate conical pressure adjustable spring fitted providing a
downstream pressure range of 0.2 - 17 bar g.
DP27SY has a pressure spring with a range of 0.2 - 3 bar g.
Body design conditions PN25
Maximum design pressure 17.2 bar g @ 232°C
Maximum design temperature 232°C @ 17.2 bar g
Minimum design temperature -10°C
Maximum upstream pressure for saturated steam service 17 bar g
Maximum operating temperature 232°C
Minimum operating temperature 0°C
Note: For lower operating temperatures consult Spirax Sarco.
Maximum differential pressure 17 bar
Designed for a maximum cold hydraulic test pressure of: 25.8 bar g

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




Pressure bar g
Temperature °C
A
Steam
saturation
curve
C
BD

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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
DP27S (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.
DP27SY (Figure 1)
The DP27SY is supplied as the DP27S, but has a lower rate pressure adjustment spring for
a downstream pressure range of 0.2 - 3 bar.
Pressure adjustment spring
Downstream internal
pressure balance pipe
Pressure setting adjustment screw
Lock-nut
Recommended downstream pressure
balance pipe connection
(refer to Section 3.8, page 10)
Fig. 1
3. Installation

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Pressure
sensing
pipe
Small bore
drain
Strainer with
100 mesh stainless
steel screen
Separator
Steam
supply Spiratec
sensor
chamber
Float type
steam trap
Pressure
reducing
valve
DP27S
0.9 m or
15 pipe diameters clear
on either side
See Section 3.6, page 9
Downstream isolating valve to
provide no-load conditions for
setting pressure reducing valve
Safety
valve
Discharge
pipe
Isolation
valve
Strainer
3.2 Fitting (Figures. 2, 3 and 4)
The valve should always be fitted in a horizontal pipeline with the main diaphragm
chamber below the line (Figure 2). 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 3).
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 4.
Separator
Compressed
air
Fig. 2 Recommended installation
Installation for
compressed air Compressed
air trap
Float type
steam trap
Alternative for
draining
separator
Strainer Sight
glass
Isolation
valve

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Fig. 3 Two pressure reducing valves in parallel
Steam
supply
Q See Section 3.6
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
Q See Section 3.6
Fig. 4 Two pressure reducing valves installed in series
Q
Q
Q
Separator
Trap set Trap set

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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 DP27S. 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 3,
page 9. Alternatively a bypass line can be used (see Figure 6, page 12). 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.