Adjusting Mass Flow on a Varian Cryo Platform.

Gas Regulator Tuning Procedure (MK1)

• With the CCC cold and operating at equilibrium (running at least 3 hours), the gas regulator valve should quickly be closed to finger tight and then opened 5 turns. The vernier needle valve on the inlet side of the cold loop should also be opened fully. At this point the mass flow through the system will be a maximum. This maximum mass flow, M_max. is typically between 39 and 45 SLM when the entire system is cold, stable and the compressor is charged to 210 psi. Record M_max·
• The vernier needle valve should then be closed until the mass flow becomes stable at: M_max/2 + 9
• Finally, close the gas regulator needle valve slowly until the mass flow through the cold loop stabilizes at 18. This may take several minutes to accomplish as the regulator bottle takes time to charge/discharge and reach equilibrium.