See this page for the history: Coldhead tripping off record due to LCW temperature
You can check the LCW outlet temperatures from the coldhead compressors via https://e906-gat1.fnal.gov/data-summary/e1039/target-all.php
Select:
- When the outside LCW temperatures are above 105 F, the coldhead compressor indicators will become RED. See the following overview screen.
From the Manual (See Coldhead Compressors Manual > Helium Compressor Manual.pdf) - First step is to keep the Dewar Pressure stabilized until the Liqefier is back to normal operation.
(a) Set the Liquefier to Manual Mode, and make sure only the outlet flow
(b) Set the Liquefier's outlet flow such that the Dewar pressure is regulated around the set pressure (6.5 psig) and does not have a trend increase above 8psig.
You may need to plot the Dewar Pressure (PT503 A/B) on strip charts to see the trend while adjusting the outlet flow (FCAQMC / FCBQMC)
Note: when you enter a value in FCAQMC / FCBQMC box, press the ENTER key once the value is entered.
(In the following example screenshot, the outlet flow was set to 30slm which is higher than the normal ~2 slm)
You will need to keep monitoring the Dewar pressure and try to bring the outlet flow down to 2slm if possible to preserve LHe amount. - Go to the "Helium Compressors" screen
- Double-click the "Reset" buttons next to those RED indicators to clear those Alarms.
If the compressors can't be reset by doing that, then you will have to wait until the LCW outlet temperatures from the coldheads are below 90 F, and try it again.
If the LCW Temperatures < 90 F and the resetting doesn't work. Then, you will need to access the hall and then press the "Reset" button (Black Colored button) on the corresponding coldhead compressor,
and after that, Double-click the "Reset" buttons next to those RED indicators to clear those Alarms. - Ensure the Enable and Remote buttons on the Helium Compressors screen are ON positions for both Liquefiers
- Once the Alarm is cleared, then go to the Liquefier screen, and switch the Liquefier to RUN + Auto + Liquefy mode.