4.12 Accessories
Always install a shutoff valve and pressure gauge at both the inlet and outlet, and a shutoff valve
in the bypass line. Ball valves, which will not retain condensate, are recommended for inlet and
outlet shutoff valves. The bypass pipe should be at least one half the size of the inlet pipe.
4.13 Piping Size / Diffuser
If the secondary steam flow velocity is expected to be more than 30 m/s (100 ft/s), install a
diffuser in order to keep the flow velocity below 30 m/s (100 ft/s). If the distance between the
reducing valve and the steam-using equipment is great, a possible drop in pressure should be
taken into consideration when selecting the piping size.
4.14 Two-stage Pressure Reduction
Two-stage pressure reduction should be performed whenever the pressure cannot be reduced
to the desired level with a single COS/COSR due to operating range limitations, such as when
the reduction ratio is greater than 10:1.
Globe Valve
Diffuser
Pressure
Gauge
Inlet
Bypass Valve
COS/COSR
Shutoff
Valve
Shutoff
Valve
Pressure
Gauge
Bypass Valve
Shutoff
Valve
COSR
Shutoff
Valve
Outlet
Safety Valve
(Relief Valve)
Pressure
Gauge
Straight piping: 10 d or longer upstream 15 d or longer downstream
Pressure
Gauge
Ball Valve
COS/COSR
Ball Valve
Pressure
Gauge
Safety Valve
(Relief Valve)
A strainer should be installed ahead of the COSR. The strainer should be 60 mesh or finer,
but not so fine that it causes constriction of the flow area and a subsequent pressure drop.
The strainer should be installed horizontally and at 90° to its normal orientation to the pipeline,
in order to prevent condensate accumulation in the screen body (see picture).
4.15 Strainer Installation (COSR)
English
11
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