The incoming helium to the fridge is controlled by the fridge valves, namely the run valve and the bypass valve. Operational procedures are explained in on this page [Fridge Valve Control System at NM4].
The outgoing helium from the fridge is controlled by the gate valve and the gate-valve bypass. Operational procedures are explained in this page.

Procedures

Important Facts

How long does the fridge would last if the starting liquid level is 100%? ~ 8 hrs from (100% to 10%) with maintaining cernox 7 temperature below 50 K
Note: Set Separator flow to 10slm.
https://e906-gat1.fnal.gov/data-summary/e1039/target-all.php?sel_mode=date_time&Y0=2024&M0=06&D0=16&h0=20&m0=00&s0=00&Y1=2024&M1=06&D1=17&h1=11&m1=10&s1=00&Cryo+Temperature_Cernox+7&Cryo+Level_Nose+LHe+Level
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How long does the fridge would last if the starting liquid level is Heat Ex. Bottom? ~16 hrs
How long would the fridge be cold if the level probe reaches zero? ~1.5-2.0 hrs