3.10.2 Feed Water Valve Specification
Valve sizes: ½” to 2”
Servo Torque: 37ft.Ib
NEMA 4 rated
IP65 rated
Position feedback potentiometer from servomotor
Flange spec: ANSI 300Ib or PN40
Note: The feed water valve is not classed as a full shut off valve (bubble tight). However, the
tolerances are set very tight thus restricting flow through the valve. For this reason it is advised to place
a normally closed solenoid valve in series with the feed water valve. The further advantage of this is
that in the event of a power failure the feed water valve will remain in the position at loss of power,
however, the normally closed solenoid valve will shut off restricting flow to the boiler.
It is essential that an adequate strainer (100 micron) is placed on the feed water inlet line. The pressure
drop across the strainer must be taken into account when sizing the feed water valve.
The following table illustrates the pressure tests on the valves:
Nominal Size of Line Maximum Allowable
Pressure*
Maximum Allowable
Temperature
Test Pressure
½” (15mm) 300 PSI (20 bar) 446°F (230°C) 870 PSI (60 bar)
¾” (20mm) 300 PSI (20 bar) 446°F (230°C) 870 PSI (60 bar)
1” (25mm) 300 PSI (20 bar) 446°F (230°C) 870 PSI (60 bar)
1 ½” (40mm) 300 PSI (20 bar) 446°F (230°C) 870 PSI (60 bar)
2” (50mm) 300 PSI (20 bar) 446°F (230°C) 870 PSI (60 bar)
*Please note that for the US valves with 300lb rated flanges, the maximum allowable pressure is 300
PSI. For other valves, the maximum allowable pressure is 580 PSI (40 bar).
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