172-65174MA-11 (COSR Pressure Reducing Valve) 16 Feb 2022
6
4. Precautions for the Installation of Additional Fittings Before or After the Reducing Valve
In order to ensure stable steam flow, the piping upstream and downstream of the
COSR must be straight runs. If a COSR is installed either directly before or after
an elbow or control valve, unevenness in steam flow may result in chattering and
unstable pressure.
To ensure stable steam flow, it is recommended that the COSR be installed on
straight runs of piping, as illustrated below.
①
Inlet (primary side) of the COSR
NOTE: d = pipe diameter
Maintain a straight piping run of
10 d or more
when a manual
valve, a strainer or an elbow, etc.
is installed.
(Example: if nominal size is 25 mm (1
in), have 250 mm (10 in) or more)
Maintain a straight piping run of
30 d or more
when an automated
valve (on-off valve) is installed.
(Example: if nominal size is 25 mm (1
in), have 750 mm (30 in) or more)
②
Outlet (secondary side) of the COSR
Maintain a straight piping run of
15 d or more
when a manual
valve, a strainer or an elbow, etc.
is installed.
(Example: if nominal size is 25 mm (1
in), have 375 mm (15 in) or more)
Maintain a straight piping run of
30 d or more
when a safety valve
is installed.
(Example: if nominal size is 25 mm (1
in), have 750 mm (30 in) or more)
Maintain a straight piping run of
30 d or more
when another
COSR is installed. (Two-stage
pressure reduction)
(Example: if nominal size is 25 mm (1
in), have 750 mm (30 in) or more)
Maintain a straight piping run of
30 d or more
when a control
valve or an automated valve (on-
off valve) is installed.
(Example: if nominal size is 25 mm (1
in), have 750 mm (30 in) or more)
10d or more
COSR
Valve,
Strainer,
Elbow, etc.
Less
than
10d
COSR
Valve,
Strainer,
Elbow, etc.
30d or more
Automated
Valve
COSR
Less than
30d
COSR
Automated
Valve
COSR
15d or more
Valve,
Strainer,
Elbow, etc.
Less than
15d
COSR
Valve,
Strainer,
Elbow, etc.
30d or more
Safety Valve
COSR
Less than
30d
Safety Valve
COSR
COSR
Pressure
Reducing
Valve
30d or more
COSR
Pressure
Reducing
Valve
Less than
30d
Control or
Automated
Valve
COSR
30d or more
COSR
Control or
Automated
Valve
Less than
30d
