7. After the setting of the internal relief valve is confirmed,
open the shut-off valves located on the pump discharge
line and the bypass return line and resume normal
operation of the pump.
8. To confirm the setting for the ZV200 external bypass
valve, slowly close the shut-off valve in the pump’s
discharge line and record the pressure shown on the
gauge. The difference between the pump’s discharge
pressure and the tank pressure (before pumping) is
the setting of the external bypass valve.
8. If the pump is equipped with an internal relief valve,
the ZV200 external bypass valve should be set 20–25
psi (1.38 to 1.72 bar) below the setting of the pump’s
internal relief valve. Following this guideline ensures
the liquid does not recirculate through the internal
relief valve and eliminates the possibility of erratic
“hunting” between the two valves.
9. Reopen the shut-off valve in the pump’s discharge line
and resume normal operation of the pump. Record the
pressure shown on the gauge. The difference between
the pump’s discharge pressure and the tank pressure
(before pumping) is the normal operating pressure of
the system.
10. If possible the setting of the ZV200 external bypass
valve should be 15 psi (1.03 bar) higher than the normal
operating pressure of the piping system. An operating
pressure near the external bypass valve setting may
cause the liquid to recirculate unnecessarily.
11. Adjust the pressure setting of the ZV200 external
bypass valve if necessary. The external bypass valve
can be adjusted by removing the valve cap and
loosening the locknut.
WARNING: Use caution when removing the valve
cap and follow the procedures below .
a. To
increase the pressure setting, loosen the
locknut and turn the adjusting screw
clockwise.
b. To
decrease the pressure setting, loosen the locknut
and turn the adjusting screw
counterclockwise.
12.
Once a satisfactory pressure adjustment has
been achieved, attach the “tamper-proof” seal
furnished with the external bypass valve to prevent
unauthorized adjustments.
Notice!
1. If the external automatic bypass valve is sized and set
correctly, a manual or hand operated bypass valve–
if applicable–should remain in the closed position
during normal operation. Keeping the manual or hand
operated bypass valve closed ensures the external
automatic bypass valve operates in a normal capacity.
2. Annual inspection and testing of the internal relief
valve–if applicable–and the external automatic bypass
valve are recommended. For testing procedures refer
to the adjustment procedures listed in this manual.
Stationary applications equipped with an electric
motor drive:
1. Install liquid-filled pressure gauges equipped with a
needle valve or snubber in the following locations:
a. Pump discharge gauge port or inlet side of the
bypass valve.
b. Supply tank and/or pump suction.
2. Attach an ammeter to a motor lead of the electric motor.
3. Remove the valve cap on the ZV200 external bypass
valve and adjust to the lowest pressure setting by
turning the adjusting screw
counterclockwise until
spring tension is no longer present.
Note: Do not
remove the adjusting screw .
4. Make sure the shut-off valves on the pump discharge
line and bypass return line are in a fully open position.
5. Start the pump and circulate the liquid back to the
supply tank using the discharge line.
6. Slowly close the shut-off valve located on pump
discharge line so all of the liquid flows through the
external bypass valve.
7. Slowly
increase the setting of the ZV200 external bypass
valve by turning the adjustment screw
clockwise until
the ammeter indicates the full-load current indicated on
the motor nameplate or required differential pressure is
reached. Record the pressure on the gauge mounted
on the inlet side of the bypass valve.
9. If the pump has an internal relief valve, the ZV200
external bypass valve should be set at least 20–25 psi
(1.38 to 1.72 bar) below the setting of the pump’s built
in relief valve. Following this guideline ensures the
liquid does not recirculate through the internal relief
valve and eliminates the possibility of erratic “hunting”
between the two valves.
10. If possible the setting of the ZV200 external bypass
valve should be 15 psi (1.03 bar) higher than the normal
operating pressure of the piping system. An operating
pressure near the external bypass valve setting may
cause the liquid to recirculate unnecessarily.
11. Adjust the pressure setting of the ZV200 external
bypass valve if necessary. The external bypass valve
can be adjusted by turning the adjust screw
clockwise
to increase pressure and counterclockwise to
decrease pressure.
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