<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body text="#000000" bgcolor="#FFFFFF">
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>
<div class="moz-cite-prefix">On 6/27/18 11:15 AM, George Jacobs
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:1456880357.2225753.1530112559467.JavaMail.zimbra@jlab.org">
<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"
<a class="moz-txt-link-rfc2396E" href="mailto:wcrahen@jlab.org"><wcrahen@jlab.org></a><br>
<b>To: </b>"Brian Eng" <a class="moz-txt-link-rfc2396E" href="mailto:beng@jlab.org"><beng@jlab.org></a>,
<a class="moz-txt-link-abbreviated" href="mailto:dsg-rtpc@jlab.org">dsg-rtpc@jlab.org</a><br>
<b>Cc: </b>"Bob Miller" <a class="moz-txt-link-rfc2396E" href="mailto:rmiller@jlab.org"><rmiller@jlab.org></a><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:
<a class="moz-txt-link-freetext" href="http://www.cdivalve.com/products/valves/air-compressor-valves/asme-code-safety-valves">http://www.cdivalve.com/products/valves/air-compressor-valves/asme-code-safety-valves</a><br>
><br>
> Specs: <a class="moz-txt-link-freetext" href="http://www.cdivalve.com/images/uploads/ST.png">http://www.cdivalve.com/images/uploads/ST.png</a><br>
> Drawing: <a class="moz-txt-link-freetext" href="http://www.cdivalve.com/files/upload/23/st25.pdf">http://www.cdivalve.com/files/upload/23/st25.pdf</a><br>
> Flow Chart:
<a class="moz-txt-link-freetext" href="http://www.cdivalve.com/files/upload/23/flow_charts_st.pdf">http://www.cdivalve.com/files/upload/23/flow_charts_st.pdf</a><br>
><br>
> Hope that helps.<br>
><br>
>> On Jun 26, 2018, at 4:34 PM, Carlos Ayerbe
<a class="moz-txt-link-rfc2396E" href="mailto:gayoso@jlab.org"><gayoso@jlab.org></a> wrote:<br>
>><br>
>> FYI<br>
>><br>
>> Goerge already has it.<br>
>><br>
>> -Carlos<br>
>><br>
>> ----- Forwarded Message -----<br>
>> From: "William Crahen" <a class="moz-txt-link-rfc2396E" href="mailto:wcrahen@jlab.org"><wcrahen@jlab.org></a><br>
>> To: "George Jacobs" <a class="moz-txt-link-rfc2396E" href="mailto:jacobsg@jlab.org"><jacobsg@jlab.org></a>, "Carlos
Ayerbe Gayoso" <a class="moz-txt-link-rfc2396E" href="mailto:gayoso@jlab.org"><gayoso@jlab.org></a><br>
>> Cc: "Bob Miller" <a class="moz-txt-link-rfc2396E" href="mailto:rmiller@jlab.org"><rmiller@jlab.org></a><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>
<a class="moz-txt-link-abbreviated" href="mailto:Dsg-rtpc@jlab.org">Dsg-rtpc@jlab.org</a><br>
<a class="moz-txt-link-freetext" href="https://mailman.jlab.org/mailman/listinfo/dsg-rtpc">https://mailman.jlab.org/mailman/listinfo/dsg-rtpc</a><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) <a class="moz-txt-link-abbreviated" href="mailto:jacobsg@jlab.org">jacobsg@jlab.org</a><br>
<br>
(website) <a class="moz-txt-link-freetext" href="https://userweb.jlab.org/~jacobsg">https://userweb.jlab.org/~jacobsg</a><br>
</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
Dsg-rtpc mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Dsg-rtpc@jlab.org">Dsg-rtpc@jlab.org</a>
<a class="moz-txt-link-freetext" href="https://mailman.jlab.org/mailman/listinfo/dsg-rtpc">https://mailman.jlab.org/mailman/listinfo/dsg-rtpc</a>
</pre>
</blockquote>
<br>
</body>
</html>