<html><body><div style="font-family: arial,helvetica,sans-serif; font-size: 12pt; color: #000000"><div>Hi Carlos, <br></div><div><br data-mce-bogus="1"></div><div>The MKS general spec sheet shows 10-40psi differential pressure required for proper operation for the GE50 series. You can perform a test to determine if the GE50 MFC you have operates properly with the He-CO2 mix at reduced pressure, if you so desire. </div><div><br data-mce-bogus="1"></div><div>The gas line length and ID must also be considered, length ~200ft and ID, 0.125" or length ~200ft long and ID, 0.375". Both 1/4" and 1/2" OD SS lines are available at the location.<br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div>Cheers,<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>"Carlos Ayerbe" <gayoso@jlab.org><br><b>To: </b>dsg-rtpc@jlab.org<br><b>Cc: </b>"George Jacobs" <jacobsg@jlab.org>, "William Crahen" <wcrahen@jlab.org>, "Bob Miller" <rmiller@jlab.org><br><b>Sent: </b>Wednesday, June 27, 2018 3:00:19 PM<br><b>Subject: </b>Re: [Dsg-rtpc] Questions about the gas systems<br></div><div><br></div><div data-marker="__QUOTED_TEXT__">Hi all, <br><br>after Howard email, I've been checking the numbers running in the previous emails and the numbers in George's scheme. I checked the MKS GE50A data sheet and I found that this MFC can operate as low as 10 psid in the flow range indicated in the gas supply scheme (0-200 sccm). Please, find attached a screenshot of the data sheet. <br><br>Perhaps I'm wrong due to my inexperience in these systems and I misinterpret some concepts.<br><br>Cheers<br><br>-Carlos<br><br>----- Original Message -----<br>From: "Howard Fenker" <hcf@jlab.org><br>To: dsg-rtpc@jlab.org, "George Jacobs" <jacobsg@jlab.org>, "William Crahen" <wcrahen@jlab.org><br>Cc: "Bob Miller" <rmiller@jlab.org><br>Sent: Wednesday, June 27, 2018 12:36:41 PM<br>Subject: Re: [Dsg-rtpc] Questions about the gas systems<br><br>Carlos- <br><br>If the MFC you have really requires 30 psi to operate, please consider purchasing <br>new MFC's that work at a lower differential pressure. The MKS 1179 series controllers <br>work as low as 10 psi (between the input and the output), for example. <br><br>The reason for running at the lowest funtional pressure is to have a system <br>pressure that remains below the 15psig limit for pressure-system exemption. <br><br>Howard <br><br>On 6/27/18 11:15 AM, George Jacobs wrote: <br><br><br><br>Hi All, <br><br>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><br>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><br>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. <br><br>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><br>George <br><br><br>From: "William Crahen" <wcrahen@jlab.org> <br>To: "Brian Eng" <beng@jlab.org> , dsg-rtpc@jlab.org <br>Cc: "Bob Miller" <rmiller@jlab.org> <br>Sent: Tuesday, June 26, 2018 5:24:43 PM <br>Subject: Re: [Dsg-rtpc] Questions about the gas systems <br><br>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><br>-- <br>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><br><br>_______________________________________________<br>Dsg-rtpc mailing list Dsg-rtpc@jlab.org https://mailman.jlab.org/mailman/listinfo/dsg-rtpc <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>