11
11. Two-stage Pressure Reduction
Whenever the pressure cannot be reduced to the desired level with a single
PN-
COS-16
due to operating range limitations, such as when the reduction ratio is
greater than 10:1, the pressure reducing valve should be installed at the primary
side.
PN-COS
Pressure
Gauge
Pressure
Gauge
Pressure
Gauge
Bypass
Valve
Primary
Side
Shut-off
Valve
Shut-off
Valve
Pressure
Reducing
Valve
Bypass
Valve
Shut-off
Valve
Shut-off
Valve
Safety Valve
(Relief Valve)
PN-COS
Pressure
Gauge
Pressure
Gauge
Bypass
Valve
Shut-off
Valve
Shut-off
Valve
Safety Valve
(Relief Valve)
Primary
Side
12. Accessories
Always install a shut-off valve, pressure gauge and bypass line at both inlet and
outlet.
Ball valves, which will not retain condensate, are recommended for inlet and outlet
shut-off valves. The bypass pipe should be at least
1
/
2
of the size of the inlet
(primary side) pipe.
PN-COS
Ball Valve
Ball Valve
Globe
Valve
Pressure
Gauge
Pressure
Gauge
PN-COS
PN-COS
13. External secondary pressure-sensing line (when required)
North American Models
:
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,PN-COS-16 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
PN-COS-16
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 flow rate fluctuation is
high. In addition, the rated flow rate will be greater than an internal pressure-
172-65588MA-02 (
PN-COS
Pneumatic Control Valve) 5 Sep 2014