Spirax Sarco SRV2S User manual

IM-P186-03 CH Issue 4 1
SRV2S
Pressure Reducing Valve
Installation and Maintenance Instructions
IM-P186-03
CH Issue 4
1860050/4
1. Safety information
2. General
product information
3. Installation
4. Maintenance
5. Spare parts
6. Fault finding
Printed in the UK © Copyright 2007

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1. Safety information
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 product complies with the requirements of the European Pressure Equipment
Directive 97/23/EC and falls within category 'SEP'. It should be noted that products
within this category are required by the Directive not to carry the mark.
i) The product has been specifically designed for use on steam, compressed 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.
Safe operation of this product can only be guaranteed if it is 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.
Warning
The bellows assembly gasket contains a thin stainless steel support ring which may
cause physical injury if not handled and disposed of carefully.

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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 210°C (410°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
Fig. 1 SRV2S screwed body
Spring range ID disc
2.1 Description
The SRV2S is a compact, stainless steel, direct acting pressure reducing valve designed
for applications using steam or gases such as compressed air. All wetted parts are
constructed in 316L stainless steel.
SRV2S pressure reducing valves are supplied with one of three colour coded springs which
are identified by the disc (18) located on the adjustment handwheel (2):
Grey For downstream pressure control: 0.14 to 1.7 bar g (2.03 to 24.65 psi g)
Green For downstream pressure control: 1.40 to 4.0 bar g (20.30 to 58.00 psi g)
Orange For downstream pressure control: 3.50 to 8.6 bar g (50.75 to 124.70 psi g)
Note: Where control spring ranges overlap always use the lower range to give better control.
Standards
This product fully complies with the requirements of the European Pressure Equipment
Directive 97 / 23 / EC.
Certification
This product is available with certification to EN 10204 3.1. Note: All certification / inspection
requirements must be stated at the time of order placement.
Note: For further product data see Technical Information Sheet, TI-P186-05.
2.2 Sizes and pipe connections
½", ¾" and 1" screwed BSP ( BS 21 Rp ) or NPT.
DN15, DN20 and DN25 Flanged EN 1092 PN25 and ANSI 150.
(18)
Adjustment handwheel Tamper-proof pin (2)

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The product must not be used in this region.
Body design conditions PN25
Maximum design pressure 25 bar g @ 120°C (362 psi g @ 248°F)
Maximum design temperature 212°C @ 19 bar g (413°F @ 275 psi g)
Minimum design temperature 0°C (32°F)
Maximum operating pressure for saturated steam service 19 bar g (275 psi g)
Maximum operating temperature 212°C @ 19 bar g (413°F @ 275 psi g)
Minimum operating temperature 0°C (32°F)
Note: For lower operating temperatures consult Spirax Sarco
Maximum downstream reduced pressure 8.6 bar g (125 psi g)
Maximum differential pressure 19 bar (275 psi)
Maximum recommended turndown ratio 10:1 at maximum flow
Designed for a maximum cold hydraulic test pressure of: 38 bar g (551 psi g)
Note: With internals fitted, test pressure must not exceed: 19 bar g (275 psi g)
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Temperature °C
Pressure bar g
Steam
saturation
curve
2.3 Pressure /temperature limits
Pressure psi g
Temperature °F

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3. Installation
A Steam trap
B Strainer
C Isolating valve
D Safety valve
E Pressure gauge
F Separator
3.1 General installation
Always install the SRV2S with the flow direction arrow (on the body) pointing downstream.
The SRV2S pressure reducing valve is available as follows:
Screwed ½", ¾" and 1" BSP (BS 21 Rp) or
Flanged DN15, DN20 and DN25 EN 1092 PN25 and ANSI 150.
The Spirax Sarco SRV2S pressure reducing valve should always be fitted in a horizontal
pipeline. The adjustment head may be above or below the valve.
Isolating valves should be installed, upstream and downstream of the SRV2S, with a clear run
of 8 to 10 pipe diameters on either side.
It is important that line stresses, caused by expansion or inadequate pipe support, are not
imposed on the valve body.
Upstream and downstream piping must be of ample size to avoid undue pressure drop.
Any reduction in line size should be made using eccentric reducers.
Fitting a strainer on the upstream side will give additional protection to the valve. Install the
strainer on its side to prevent the body filling with water, which will reduce the effective
screening area. If the steam supply is wet a separator/trap set should be installed upstream.
Alternatively, an adequate drain pocket and a trap from the Spirax Sarco range should
be fitted.
A pressure gauge is essential on the downstream pipework to allow setting of the operating
pressure. It is an advantage to have a gauge on the upstream side of the valve, as well.
Safety valve
A safety valve should be fitted to protect the downstream equipment from excessive pressure
(to meet local standards). 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 SRV2S should
it 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 SRV2S. Discharge pipework should
be taken to a safe place.
Note: Before actioning any installation observe the 'Safety information' in Section 1.
Note: If you experience difficulty with installation or operation of this equipment please contact:
Spirax-Sarco Limited, Charlton House, Cheltenham, Gloucestershire, GL53 8ER
Tel: [phone], Fax: [phone]
Fig. 2 Recommended installation
C1 C2
C3
F
A
B
SRV2S
D
E2
E1

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3.2 Start-up and adjustment for the SRV2S
Before final installation, all pipework should be thoroughly 'blown through' to remove dirt,
surplus jointing material, etc.
Pressure adjustment is made by turning the adjustment handwheel clockwise to increase
pressure and anticlockwise to reduce pressure.
With the upstream stop valve fully open and the downstream stop valve closed, slowly
increase the downstream pressure by turning the adjustment handwheel clockwise until the
desired pressure (shown on the downstream pressure gauge) is achieved.
Slowly open the downstream stop valve.
Under normal flow condition, the reduced pressure setting will fall slightly, but will control
under 'dead end' co ons. If required the pressure setting can be increased by readjusting the
SRV2S control. There will be a slight increase in set pressure under 'No-load' conditions.
3.3 How to make the SRV2S tamper-proof:
- When the required set pressure has been achieved, lift out the coloured spring range ID
disc (grey, green or orange) from the adjustment handwheel recess. This is carried out by
inserting a small screwdriver blade under the edge of the ID disc.
- A small loose pin will be found in the recess in the adjustment handwheel.
- This tamper-proof pin is inserted into the locking hole 'A', and into one of a ring of 10 matching
holes in the top of the spring housing. The SRV2S is now tamper-proof.
- Replace the coloured spring range ID disc firmly into the recess of the adjustment
handwheel.
A
Fig. 3
Spring range ID disc
Tamper-proof pin
Adjustment handwheel

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4. Maintenance
Note: Before actioning any maintenance programme observe
the 'Safety information' in Section 1.
Warning
The bellows assembly gasket contains a thin stainless steel support ring which may
cause physical injury if not handled and disposed of carefully.
4.1 General information
Refer to Fig 4 (page 7) for view of parts.
The valve and valve seat must be kept clean.
Any strainer fitted upstream of the SRV2S and strainer screen (15) fitted inside the SRV2S
should be cleaned regularly so that the flow to the valve is not restricted.
The internal strainer is part of the valve seat assembly. This may be withdrawn by removing
the spring housing (1) and bellows assembly and unscrewing the valve assembly, using a
32 mm A / F spanner.
4.2 How to fit a new valve and seat or clean the strainer screen:
i. Release the adjustment spring pressure by turning the adjustment handwheel (2) fully
anticlockwise.
ii. Remove the spring housing by undoing the 4 spring housing bolts (7) using 13 mm A/ F spanner.
iii. Lift out the bellows assembly (5) and the gasket (6).
iv. Using a 32 mm A /F spanner, unscrew the valve seat (11) and remove the valve, the return
spring, the strainer screen, the pushrod and the guide bush.
v. Clean the strainer screen (15) or replace with a new valve and seat assembly. Note: the valve
and seat assembly incorporates the strainer screen.
vi. Reassemble in the reverse order, using new gaskets, ensuring that the components and
seating faces are clean.
vii. Tighten the valve seat (11) to the following torque 162 - 198 N m (119 - 146 lbf ft).
viii. Tighten the spring housing bolts (7) to the following torque 18 - 24 N m (13 - 18 lbf ft).
4.3 How to fit the new bellows:
Follow Steps i to iii, Section 4.2, then proceed as follows:
ix. Replace the bellows gasket and assembly, adjustment spring and the spring housing, and
tighten the spring housing bolts (7) to the following torque 18 - 24 N m (13 - 18 lbf ft).
4.4 How to fit a replacement pressure adjustment spring:
Follow Steps i and ii, Section 4.2, then proceed as follows:
x. Replace the spring (4) and bonnet assembly and tighten the spring housing bolts (7) to the
following torque 18 - 24 N m (13 - 18 lbf ft).
xi. Lift out the spring identification disc (18) and press in a new disc (if spring range has been
changed).
4.5
xii. The lower body section can be cleaned internally by removing the bottom cap (16).
xiii. Replace the 'O' ring (13) and retighten the bottom cap (16) to the required torque.
Table 1 Recommended tightening torques
or
Item No. Part N m (lbf ft)
mm
7 Hex. bolts 13 A / F M8 x 25 18 - 24 (13 - 18)
11 Valve seat 32 A / F 162 - 198 (119 - 146)
16 Bottom cap 32 A / F 115 - 125 (85 - 93)

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Fig. 4
Pressure
adjustment
spring
2
7
Spring housing
hexagon bolts
Bellows assembly
19
11
Valve and seat
assembly
18
4
5
6
12
6
Gasket set
12
6
13
1
15
16

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*
*
*
*
*
5. Spare parts
The spare parts available are shown in heavy outline. Parts drawn in broken line are not
supplied as spares.
Available spares
Grey 0.14 to 1.7 bar g 4, 18
Pressure adjustment spring Green 1.40 to 4.0 bar g 4, 18
Orange 3.5 0 to 8.6 bar g 4, 18
Bellows (stainless steel) 5, 6
Spring housing hex. bolts (set of 4) 7
Valve and seat assembly 6, 11, 12, 15, 19
Set of gaskets /'O' ring 6, 12, 13
Common to all sizes.
How to order spares
Always order spares by using the description given in the column headed 'Available spares' and
state the size, type and pressure range of the reducing valve.
Example: 1 off Spirax Sarco pressure adjustment spring, having a downstream pressure range
of 3.5 to 8.6 bar g (orange) for a DN15 type SRV2S pressure reducing valve.

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Fig. 5
Pressure
adjustment
spring
7
Spring housing
hexagon bolts
Bellows set
19
11
Valve and seat
assembly
18
4
5
6
12
6
Gasket set
12
6
13
15

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6. Fault finding
Before investigating any fault ensure that both upstream and downstream isolating valves
are shut off and that the SRV2S is vented.
SYMPTOM Downstream pressure increases above set pressure.
CAUSE 1 Bellows failure or bellows leakage.
CHECK and CURE Replace bellows set. Check valve is not subject to rapid oscillation causing
bellows fatigue failure.
CAUSE 2 Damage or erosion to valve seat.
CHECK and CURE Replace valve and seat assembly.
CAUSE 3 Excessive dirt / scale build up on seat and head, blocked pressure.
sensing orifice/sticking pushrod.
CHECK and CURE Replace valve and seat assembly.
SYMPTOM Downstream pressure is below set pressure under
full load conditions.
CAUSE 4 Valve was set at 'No-load'.
CHECK and CURE Reset at full load (Refer to start-up and adjustment, Section 3).
CAUSE 5 Valve is undersized for required duty.
CHECK and CURE Check maximum installed load and valve size selected and installed.
SYMPTOM Adjustment knob will not turn.
CAUSE 6 Tamper-proof pin is preventing adjustment.
CHECK and CURE Remove pin from cap.
SYMPTOM Hunting/ unstable control.
CAUSE 7 Wet steam.
CHECK and CURE Ensure lines are properly trapped, install separator if necessary.
CAUSE 8 Externally transmitted signals.
CHECK and CURE Check proximity of valve to other associated control equipment e.g.
on/ off valves.
CAUSE 9 Sticking pushrod due to dirt /scale build up.
CHECK and CURE Replace valve and seat assembly.

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