From what I can see, it looks like what you're doing is reasonable.
I mean, you typically want to fill sometime before the helium level gets to
the minimum allowed level. From what I can tell from the chart, when
the probe reads 100mm that means you have around 36l of liquid left, and
the minimum allowed is around 18. And the full volume is like 115l.
So you should be putting around 80l in the magnet, plus whatever is lost cooling
the line. I've been told anecdotally that that is around 10l. So you
should be using roughly 90l of a 100l dewar? That seems reasonable to me.
I suppose you could go a bit longer but then if you run into any issues your
safety margin is decreased.
Cheers,Mike
On Monday, May 19, 2025 at 09:38:31 AM MDT, Stephen Nolte via groups.io wrote:
Hello,
I’ve been following the notes of our previous technician to perform
the liquid helium fill when our probe reading is around 100. I also found
the attached helium probe calibration chart, and I’m wondering if
I’m performing the helium fill prematurely. Does the digital readout
value on the probe refer to the “Probe reading (mm)” column
or the “He level in can (mm)” value? Should I be waiting
a little longer before the fill?
Thank you!
_______________________________
Stephen Nolte| Chemistry Technician
Millersville University
717-871-7413
-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#2352): https://urldefense.com/v3/__https://ammrl.groups=
.io/g/main/message/2352__;!!PvDODwlR4mBZyAb0!QN6q2DySQqRF7fwu9Jx6IbZY1ed18l=
3qTZ8jRTkHY6tk0kQQFT-uw3o21I1mEQ5nRPGTtBzYDt2YV1-SNKClpwcZYJNW$
Mute This Topic: https://urldefense.com/v3/__https://groups.io/mt/113194325=
/7559972__;!!PvDODwlR4mBZyAb0!QN6q2DySQqRF7fwu9Jx6IbZY1ed18l3qTZ8jRTkHY6tk0=
kQQFT-uw3o21I1mEQ5nRPGTtBzYDt2YV1-SNKClp8QIcWES$
Group Owner: main+owner_at_ammrl.groups.io
-=-=-=-=-=-=-=-=-=-=-=-
Received on Mon May 19 2025 - 09:09:24 MST