172-65169MA-08 (MC-COS Multi-control Valve) 28 May 2010
14
13. External secondary pressure-sensing line (when required)
North American Models are factory prepared for external sensing.
An external sensing line MUST be installed.
DO NOT SUPPLY STEAM until all piping and a 10 mm (
3
/
8
in) secondary
pressure sensing line with a slightly falling pitch have been properly installed.
Install a shutoff valve in the pressure sensing line for maintenance purposes.
Keep the shutoff valve open at all times during operation. If the shutoff
valve is closed, MC-COS will fully open and PRIMARY PRESSURE WILL BE
SUPPLIED TO THE EQUIPMENT (see “Piping Example” on next page).
CAUTION
Non-North American Models:
Factory-standard MC-COS employs an internal secondary pressure-sensing
channel built into the body, saving the need to install an external pressure-
sensing line to detect the secondary pressure.
Installation of an external secondary pressure-sensing line involves closing the
internal pressure-sensing channel and installing a line from the sensing line port
to the point where pressure should be controlled. This can increase stability of
pressure control where steam loss in secondary piping and flowrate fluctuation is
high. In addition, the rated flowrate will be greater than an internal pressure-
sensing channel under the operational pressure reduction ratio of 2:1 or more.
Installation procedure
1)
Loosen and remove the bolts that attach the pilot body to the main body (15 –
50 mm (
1
/
2
– 2 in)) or the pilot cover (65 – 100 mm (2
1
/
2
– 4 in)) and remove
the pilot body.
2)
Install the blind pin (optional) by first removing the connector from the main
body or pilot cover and then substituting the blind pin.
3)
Re-install the pilot body and fasten the bolts evenly to the proper torque
(see Reassembly, page 29).
4)
Remove the plug Rc(PT)
⅜
or NPT
⅜
and connect the secondary pressure
sensing line.
5)
Install the secondary pressure sensing line with a slightly falling pitch. The end
of the secondary pressure sensing line should be connected to the place on
the main piping where the pressure is to be sensed (see the piping example
on next page). A shut-off valve and union should be installed in the secondary
pressure sensing line.
