Dear Colleagues,
before proposal about humidity sensor calibration I assumed that separator will finish its job this year. If not, we CAN NOT disassemble separator - no questions!
In this case the most easy way for calibration is to use as a source of cold liquid nitrogen. The temperature is suitable. All instabilities will be corrected by the Xe pressure stabilization.
So, I can start production of the independent system for the calibration. I hope I can use current CRDF for it (if collaboration agrees).
1. Vacuum chamber with liquid nitrogen volume, Cu heat bridge, Xe volume, H2 heatexchanger.
about 1000 Eur manpower and 700 Eur materials.
2. 1 cryogenic Pt 100 - Claude has it.
3. 1 pressure sensor for Xe. We can not use pressure sensor from H2 lines. It means we have to buy it.
http://www.keller-druck.com/picts/pdf/engl/33xe.pdf
If we can buy PPA 33X for 10 bar with RS485 and "extra precision" we can make unic measurements with absolute calibration of humidity sensor on the level +/-3% at 20-30 ppb.
Could I ask you to get offer from Keller?
4. We will not use differential pressure sensor form the separator. Exist another methods to control the system.
5. Electronics from separator will control the humidity calibrator. Nothing new exept software (Peter's job) and cabling.
6. Job with humidity calibration will take 2 weeks of 3 persons (I, Marat and Peter).
This job can be done in Gatchina before the end of September and in October in PSI.
I really think that we have to do it! This method will be MORE precise then in the firm which produced humidity sensor. The reason is very simple, we have to calibrate in a VERY narrow range at OUR conditions (10 bar of hydrogen) with OUR electronics. Real conditions and electronics can produce additional errors.
With best regards Sasha.