1. LN2 Circuit for MIT Test, September 2005
Exhaust to atmosphere
LN2 Circuit for MIT Test, September 2005
Flow Monitor
LN2 Storage Vessel V1 G1
Exhaust to atmosphere
Cryostat V2
Nitrogen or helium gas bottle V3
150 l Dewar

2. Operation V1 V2 V3 G1 Fill Cryostat Open Closed Empty Cryostat
Monitor remaining LN2 in cryostat
Measuring the LN2 remaining in the cryostat after emptying.
The flow monitor must integrate the flow over time as the cryostat gradually warms up to room temperature. The flow monitor is placed far away from the cryostat to ensure that the nitrogen gas has reached ambient temperature when it passes through the flow monitor - or a gas heater is inserted into the exhaust line.
Dear Colleagues,
Here are our thoughts on the requirements for the MIT test this autumn. As I see it the important thing is to measure the amount of LN2 remaining in the cryostat after blowing out the LN2 from the full cryostat, because it is a safety issue. The attached scheme shows the minimum equipment required.
After filling the cryostat the LN2 is blown out into the temporary storage Dewar. Then the system is sealed off allowing the boil off from the cryostat to flow through a gas flow monitor to atmosphere. A simple gas meter will do. The gas will need to be warm since they measure volume flow. I am pressing Cryonorm for a price for their heater and if necessary we could use this. The lines and valves do not need to be thermally insulated and almost anything would do for the test.
Now a question for Peter Titus. Would you be able to supply all the bits? If not, we will have to discuss.
Cheers, Roger
Dr J. R. J. Bennett