Improvement of Ultimate Pressure of Oil-Free Reciprocating Pump for Tritium Service

Oil-free reciprocating pump has been developed for tritium services at Tritium Process Laboratory (TPL) in Japan Atomic Energy Agency, and used for more than 20 years without any big trouble. One disadvantage of the above reciprocating pump is rather high ultimate pressure and drastically decreasing of the pumping performance at the lower suction pressure. The main reason would be that the check valves could not open enough at lower suction pressure, which are installed in the piston of the pump. In order to improve this disadvantage, solenoid valves option was tested instead of the check valves. Intentional opening & closing of the solenoid valves, linked with reciprocating motion cycle of the pump, improved more than one order of the ultimate pressure drastically. High evacuation performance was also demonstrated by the combination of molecular DRUG pump and the improved reciprocating pump with solenoid valve.