<html><body><div style="font-family: arial,helvetica,sans-serif; font-size: 12pt; color: #000000"><div>Hi All,<br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div>The 25 psi relief valve setpoint is too low. The MFC require 30 psi to operate. The 25 psi relief was chosen for use when the system used a rotometer. This was an earlier design.<br></div><div><br data-mce-bogus="1"></div><div>Please consider the 75 psi setpoint relief valve to be a place holder with a reasonable setpoint. You can choose any relief valve you prefer.<br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div>The orifice selected is a standard precise orifice, O'Keefe Controls, we use these in many gas cylinder supply setups of this type. You can also consider it, a place holder and choose one of your own preference. </div><div><br data-mce-bogus="1"></div><div>There is a short write up I did on this system a couple weeks ago located on the jlab O: drive. I am out of the office today, perhaps Brian or Mark can send you a copy of it. <br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div>George<br data-mce-bogus="1"></div><div><br></div><hr id="zwchr" data-marker="__DIVIDER__"><div data-marker="__HEADERS__"><b>From: </b>"William Crahen" <wcrahen@jlab.org><br><b>To: </b>"Brian Eng" <beng@jlab.org>, dsg-rtpc@jlab.org<br><b>Cc: </b>"Bob Miller" <rmiller@jlab.org><br><b>Sent: </b>Tuesday, June 26, 2018 5:24:43 PM<br><b>Subject: </b>Re: [Dsg-rtpc] Questions about the gas systems<br></div><div><br></div><div data-marker="__QUOTED_TEXT__">So this valve has a minimum crack pressure of 25 psig, which would be <br>okay, it just means that all piping going from the gas shed to the mass <br>flow controller must be per ASME B31.3, or perhaps B31.9 (We used 31.9 <br>for the hall D FDC, and Tim Whitlatch is on the pressure system <br>committee, so I don't see a reason we can't use for the CO2/Helium <br>stuff). I see what appears to be an orifice disc on the high pressure <br>side of the supply regulator-do we have the cut sheet on that? that is <br>typically the design limiter for un-controlled flow- you assume the <br>regulator fails at full gas bottle pressure (3500 psi?) and calculate <br>what flow can occur- that sizes your relief valve.<br><br>On 6/26/2018 4:47 PM, Brian Eng wrote:<br>> Not sure if it's on hand or not, but here's some information on that ASME relief valve from their site: http://www.cdivalve.com/products/valves/air-compressor-valves/asme-code-safety-valves<br>><br>> Specs: http://www.cdivalve.com/images/uploads/ST.png<br>> Drawing: http://www.cdivalve.com/files/upload/23/st25.pdf<br>> Flow Chart: http://www.cdivalve.com/files/upload/23/flow_charts_st.pdf<br>><br>> Hope that helps.<br>><br>>> On Jun 26, 2018, at 4:34 PM, Carlos Ayerbe <gayoso@jlab.org> wrote:<br>>><br>>> FYI<br>>><br>>> Goerge already has it.<br>>><br>>> -Carlos<br>>><br>>> ----- Forwarded Message -----<br>>> From: "William Crahen" <wcrahen@jlab.org><br>>> To: "George Jacobs" <jacobsg@jlab.org>, "Carlos Ayerbe Gayoso" <gayoso@jlab.org><br>>> Cc: "Bob Miller" <rmiller@jlab.org><br>>> Sent: Tuesday, June 26, 2018 4:30:48 PM<br>>> Subject: Questions about the gas systems<br>>><br>>> Hi guys- Carlos provided me with some documentation on the parts you are<br>>> planning to use- I see a parts list showing a relief valve RV1 = STLMO<br>>> model ST25-1/4", set to crack at 75 psi, presumably accommodating 74<br>>> scfm at some higher pressure. Do you plan to use this? If so, I need to<br>>> see a cut sheet on it with flow curves, etc. Alternately, is this<br>>> replaced by the CONRADER valve I find elsewhere in this documentation?<br><br><br>_______________________________________________<br>Dsg-rtpc mailing list<br>Dsg-rtpc@jlab.org<br>https://mailman.jlab.org/mailman/listinfo/dsg-rtpc<br></div><div><br></div><div data-marker="__SIG_POST__">-- <br></div><div>George Jacobs<br>Physics Detector Support Group<br>Jefferson Lab<br>12000 Jefferson Ave.<br>STE 12<br>Newport News, VA 23606<br><br>(office) 757-269-7115<br><br>(cell) 757-876-0480<br><br>(email) jacobsg@jlab.org<br><br>(website) https://userweb.jlab.org/~jacobsg<br></div></div></body></html>