[labnetwork] Question regarding SF6 intermediate gas delivery line pressures

[Paolini, Steven]

Bob,
   My method takes into account how many "sticks" are on the VMB, how far a distance from the gas source, and what the total flow rate could be with all equipment running at max. I start at 20 PSI and add 10 psi per liter of possible flow at the cylinder regulator if the run is 50' of 1/4" line or less. I would add 5 PSI for each additional 25' of tubing with a maximum of 100 into the VMB's. I prefer not to overdo the cylinder regulator pressure since it could result in frosting up the regulator from the J.T. effect if you are using a lot of gas volume (>10 liters). Your actual mileage will vary :)
Regards,
  Steve Paolini
Harvard University Center For Nanoscale Systems

-----Original Message-----
From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Robert M. Hamilton
Sent: Thursday, March 07, 2013 12:50 PM
To: labnetwork at mtl.mit.edu
Subject: [labnetwork] Question regarding SF6 intermediate gas delivery line pressures

Colleagues,

What is the preferred line pressure for delivering SF6 from a gas vault to a valve-manifold box?

The SF6 cylinder pressure in our indoor cylinder vault is
~320 psi. The final delivery pressure is ~18-22 psi. There is a cylinder regulator at the cylinders as well as line pressure regulators in the VMB. Our delivery volume varies from ~100 sccm to 1.5 slpm.

Thanks for any enlightenment,
Bob Hamilton


--
Bob Hamilton
Marvel NanoLab
University of CA at Berkeley
Rm 520 Sutardja Dai Hall
Berkeley, CA 94720-1754
bob at eecs.berkeley.edu
(e-mail preferred)
510-809-8600
510-325-7557 (mobile - emergencies)


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