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3. Installation and commissioning
Note: Before actioning any installation observe the 'Safety information' in Section 1.
Important note
The valves covered by these instructions are for use with Spirax Sarco EL and SA control
systems Types 121, 122, 123 and 128. (The Types 122 and 128 SA control system are not
suitable for valves above 1" / DN25).
3.1 General installation
The valve should always be fitted in a horizontal pipeline with the flow in the direction indicated
by the arrow marked on the body with the sensor in a vertical plane below the pipeline as shown
in Figure 1 (SA control system). Valves should be mounted in the pipeline in accordance with
the actuator Installation and Maintenance Instructions.
A suitable strainer should always be fitted upstream of the valve. Additionally on steam
installations a separator should be fitted before the valve, plus a steam trap set on applications
where condensate may accumulate upstream of the valve.
Warning:
The SA control system actuator must be securely connected to the valve via the
screwed connection on the bottom of the valve and the half union coupling on the actuator
before any fluid is allowed to pass through the valve.
Similarly, the actuator should not be disconnected from the valve until the valve itself is
fully isolated.
It is important that line stresses i.e. expansion or inadequate supporting of the pipe are not
imposed on the valve body.
If the valve is properly sized for the duty it has to perform it will often be smaller than the
pipeline. This is particularly so where the medium passing through the valve is steam, in which
case any reduction in line size should be made using eccentric reducers. The piping on both
upstream and downstream sides of the valve must be of ample size to avoid undue pressure
drop in the line and any reduction to meet the size of the valve should be made close to the
valves as shown in Figure 1.
It is advisable to protect the valve by fitting a strainer on the upstream side. By fitting the strainer
on its side where the medium is steam you will prevent the body filling with water which would
reduce the screening area.
In most steam installations, water formed by condensation due to radiation losses will be
present in the upstream pipeline and should be removed by an adequate drain point and trap,
as shown in Figure 1.
3.2 Bypass arrangements
It is recommended that isolating valves be fitted upstream and downstream of the control
valve together with a manual regulating valve to bypass the group (see the dotted pipework,
Figure 1). The process may then be controlled by the bypass valve while the control valve is
isolated for maintenance purposes.
3.3 Commissioning
For commissioning instructions refer to the Operation, Installation and Maintenance Instructions,
covering Spirax Sarco control systems.
IM-S21-01 CH Issue 7
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