Re: [AMMRL] Quench narrowly avoided? Filling small magnets connected to helium recovery

I’m a great fan of measuring the pressure directly on the magnet - before any check valves etc., because that is what can lead to a pressure-induced (slow or fast) quench. It also gives you an idea how many (sometimes too many and/or too strong ones!) check valves are installed between the magnet and the helium balloon. 

It’s also not a bad idea to add an additional emergency check valve which vents to atmosphere in case of too high back pressure.

Attached is a photo of such a setup (Oxford AS600), not visible is the T-piece where the thin Tygon tube attaches to the recovery line some 2 m downstream.

If liquid shoots out like you describe it sounds as if back pressure may be too high. Trying to fill with rather low (0.9 psi as you wrote) will lead to a very inefficient transfer (helium evaporating inside the transfer line because of too long contact time) - you’ll mostly transfer gas and risk boiling off more than you replenish & possibly quench the magnet…

(left: 0.7 psi emergency check valve, top: psi-sensitive manometer, right: standard 0.15 psi check valve to HRS.

Cheers

Bert



Hi all,

Pictures attached as promised. The 300 already had a check valve on the helium stack before connecting to recovery manifold. The valve on the 600 was added in preparation for the recovery system. Having the check valve at the exhaust port led to too much torque on the system. Moving the valve in line with the manifold and whip relieved the strain.

Copper tubing shown is 1.5".

All flanges on the manifold are KF25. Whip to copper connection is KF40.

The barb hose flange adapters have a smaller ID than intended from a miscommunication when ordering the parts. As long as the ball valve is open during fills I don't think it should matter; technically I should be able to remove the flow meters and seal those two ports without affecting anything.

Kind regards,

Luke

==

Luke Fulton, PhD CHEM BLDG R003

NMR Core Facility Director nit 3060

COR²E & Department of Chemistry 5 N Eag= leville Road

University of Connecticut Storrs, CT 06279

email: fko24003_at_uconn.edu

(alias): luke.fulton_at_uconn.edu

mobile: (603) 953-5275

Office: (860) 486-4069

---

<20250419_124251.jpg>

<20250419_124343.jpg>

<20250419_124812.jpg>