Some years ago when I was at Minnesota, there was an occasion where the pumps on a pumped Oxford 800 were off for longer than 4 Hr because of some repair work being done. We did shut off the needle valve for the inlet to the helium refrigerator, and the valve in the vacuum line to the pumps during that time, and as I recall saw a total increase in temperature of a couple hundredths of a degree. I certainly would recommend having a good enough UPS or some alternative power source for the system that monitors the magnet parameters, so you can continue to track it even when the pumps are off. The pumps on the Oxford systems consume about 500 watts, so if you wanted a backup generator just for the pumps it wouldn't need to be very big.
David Live
Senior Research Scientist
Complex Carbohydrate Research Center
University of Georgia
315 Riverbend Rd.
Athens, GA 30602
706-542-6262
________________________________
From: Seabrook, Genevieve <Genevieve.Seabrook_at_uhnresearch.ca>
Sent: Thursday, November 9, 2017 2:09 PM
To: AMMRL
Subject: AMMRL: emergency power shutdown
Hi everyone,
Our building management wants to do a full 4h emergency power shutdown for maintenance. This is NOT a real/serious problem if your magnets are not subcooled magnets. It’s just a real pain because you need to warm-up your CryoProbes, fully shutdown the spectrometers, loose a day dealing with this and hope that when the emergency power is restored all the instruments will come back up with no problem.
But this message is more intended to NMR managers with subcooled magnets because now it is serious business and we need to keep pumping the magnets no matter what.
Of course we have a UPS for each 800MHz spectrometers. One of the 800MHz has a relatively new UPS but the other 800MHz has a 3 years old UPS and we can’t trust it to last that long. We can’t even be sure that their maintenance will only last 4h anyway. The solution I am aware of at the moment, is to use a very powerful generator (renting one $$$) to keep pumping the magnet but I was wondering if anyone with subcooled magnet(s) already had to deal with long period of emergency power shutdown and how did you handle it?
Any feedback will be greatly appreciated.
All the best,
Genevieve
***************************************
Genevieve Seabrook, PhD
Scientific Associate
NMR Research & Core Facility Manager
UHN, Princess Margaret Cancer Centre
Princess Margaret Cancer Research Tower (PMCRT)
4th floor, Room 4-902
101 College Street
Toronto, ONT, M5G 1L7
Mobile: 416-629-7391
Genevieve.Seabrook_at_uhnresearch.ca
Received on Fri Nov 10 2017 - 10:11:53 MST