IOM
Model: 43T Pressure Relief Valve
PAGE 5 OF 10
Figure 2B: Operation Drawing for Size 8 and 10"
Starting –up
4.1 Provide pump shut-off pressure to the 43T Pressure-Relief Valve inlet, allow no system demand.
4.2 Create sufficient pressure (higher than the valve set pressure) to allow flow through the relief valve.
4.3 While relief valve is operating, wait for the valve inlet pressure to stabilize.
The pressure on the inlet side of the relief valve should be according to the factory pre-set adjusted
pressure.
4.4 Slowly allow system flow so that system pressure falls below the relief-valve adjusted pressure.
The relief-valve should slowly shut to drip-tight.
Readjusting
Tools required:
Flat head screwdriver
Adjustable wrench
The pilot valve is factory pre-set. The pre-set is clearly indicated on the pilot valve data-plate.
If readjustment to either the pressure or valve response is required, follow the following steps.
4.5 Ensure that there is nominal flow through the relief-valve.
4.6 Release the tension between the adjusting screw on the pressure-relief pilot valve and the
fastening nut by turning the fastening nut counterclockwise.
4.7 By alternately turning the adjusting screw (#4, fig.2) on the pilot valve (#3, fig.2) a half turn and then
reading the outlet pressure, gradually adjust the pressure:
Counterclockwise to decrease (-) the inlet pressure
or Clockwise to increase (+) the inlet pressure.
NOTE
: Valve response adjustment
affects pre-set pressure. Any adjustment to valve
response requires rechecking pre-set pressure, see steps 4.1 – 4.4.
4.8 Repeat the Starting-up procedure, sections 4.1 – 4.4.
