We're finally getting the last pieces setup for our imminent connection to
our helium recovery system. I have a question about the behavior I'm
observing with our back pressure regulators.
I purchased the ControlAir 710-DA regulators from McMaster-Carr. These
back-pressure regulators are rated for 0-2 psi. I have 0-3psi gauges on
them. I have a Dyson helium flow meter right in front of the back pressure
regulator.
When first setting them up, I open the regulator all the way open until
flow is observed. The first thing I notice is that even all the way open,
pressure builds to 0.5psi. That seems weird.
Next, it's very sensitive, as I begin to close down the regulator, the flow
quickly stops. What I would expect at this point, would be that the
pressure would rise and flow would again resume. What I observe is that
the pressure never rises and flow never resumes. I have barely closed down
the regulator. I've tried this on two systems. One older Oxford Magnet,
and another Bruker 600 Magnex magnet. They both seem to behave the same
way.
I suppose it doesn't matter so long as I have back pressure and flow, but
my concern is really about the flow - I want to be sure that the helium is
getting through the regulator to the recovery system. If I close down the
regular and the flow slow, but the pressure doesn't rise - is that flow
escaping the system elsewhere?
Anyway, I'd love to hear your thoughts and advice.
--
Ken Sharp-Knott
Department of Chemistry
NMR Facility Manager
Virginia Tech
(540)267-6502 (Cell)
(540)231-0885 (Office)
Received on Wed Mar 10 2021 - 03:56:07 MST