172-65169MA-08 (MC-COS Multi-control Valve) 28 May 2010
7
4. Recommended Straight Pipe Runs
In order to ensure stable steam flow, the piping upstream and downstream of the
multi-control valve must be straight runs. If a multi-control valve 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 multi-control valve be
installed on straight runs of piping, as illustrated below.
c
Inlet (primary side) of the multi-control valve
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)
Maintain a straight piping run
of
30 d or more
when another
pressure reducing valve is
installed.
(Two-stage pressure
reduction)
(Example: if nominal size is
25 mm (1 in), have 750 mm (30
in) or more)
d
Outlet (secondary side) of the multi-control valve
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 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)
Valve, strainer,
elbow, etc.
MC-COS
10 d or more
Valve, strainer,
elbow, etc.
Less than
10 d
Automatic
Valve
Automatic
Valve
30 d or more
15 d or more
Less than
15 d
30 d or more
Safety
Valve
Safety
Valve
Less than
30 d
30 d or more
Less than
30 d
Control or
Automated Valve
MC-COS
MC-COS
MC-COS
Less than
30 d
MC-COS
MC-COS
MC-COS
MC-COS
MC-COS
MC-COS
Control or
Automated Valve
30 d or more
Less than
30 d
MC-COS
MC-COS
Pressure
Reducing Valve
Pressure
Reducing Valve
