| In early June the helium compressor was running with the solenoid cold. A vavlve broke off at the suction side of the compressor. The entire helium inventory was lost. The cold box tripped off, but the compressor did not. It ran for ~ 2 hours before I came in and shut the system down. The valve was repairedby Kevin T and Neil Wong. We ran hot (>100C) nitrogen through the fourth adsorber for one week. The solenoid and cold box were allowed to warm above 273C. The compressor, all piping, cold box, solenoid and buffer tank were pumped and purged with helium three times. Liquid helium was boiled off to pressurize the system to 10 psi and bottled gas was added to allow the compressor to start. We started the compressor and ran the gas through the purifier for three weeks. During the third week we added a second purifier. The purity was not measurable with the meter that we had. An RGA was set up to give some information on the rate of scrubbing. After three weeks the gas purity was better that 2 PPM. The system was cooled down. We added ~ 75 LL of heium via boil off to the system.
As the cooling progressed it was noted that the power supply for the 80K shield heater was burnt. An auto transformer was wired into the system and will be used until a replacement power supply can be purchased. |