COOLDOWN AND STARTUP
Before the Pump is operated, all parts which come in contact with the cryogenic fluid must be cooled down to the temperature of the liquid; otherwise, sporadic vaporization will cause erratic pumping action. Proceed with cooldown as follows:
- CHECK FREE ROTATION OF PUMP BEFORE EVERY COOLDOWN AND STARTUP.
- Close discharge valve and open bypass valve.
- Slowly open the suction valve. At the beginning of cooldown the liquid in-flow will be subject to fast evaporation. As the Pump cools down sporadic vaporization will cease, and the suction valve may be fully opened.
- After a ten (10) minute cooldown, start Pump and open vent valve. If Pump does not prime in ten (10) seconds, stop motor, close vent valve, and cool down for another two (2) minutes.
- Repeat step (4) until Pump is primed (discharge pressure is developed). Close vent valve.
- Slowly open discharge valve while closing bypass valve. If Pump loses prime, open bypass valve and vent valve momentarily until discharge pressure is again developed.
- Throttle discharge valve to maintain desired discharge pressure. Opening the discharge valve excessively may break the suction flow or overload the driver.
STARTUP AFTER SHORT SHUTDOWN PERIODS
- Open suction valve and vent valve, and crack bypass valve.
- Start the Pump driver.
- When Pump primes, open discharge valve and close vent valve and bypass valve.
- Stop the Pump driver.
- Close suction, discharge, and bypass valves.
- Crack open vent valve; this will relieve pressure without drawing atmospheric moisture into the pump.