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I just want to remind folks about a couple of things;<br>
- A safety system must be fail safe under all conditions. <br>
- It cannot be network based or require external signals to operate.<br>
- The safety system is designed to protect the drift chambers from a
pressure control system failure.<br>
- Recovery from an event must be simple and safe.<br>
<br>
George<br>
<br>
<div class="moz-cite-prefix">On 5/26/2017 10:21 AM, Marc McMullen
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:e851ec8d-13ff-2c5f-a432-eed0abb599d7@jlab.org">Just an
update on this matter. We spoke with Bob Miller yesterday and he
informed us that currently DC gas is flowing without the need for
the solenoid safety system. The gas is being exhausted through
bubblers for passive pressure safety controls. The old solenoid
controls system will not be used at this time. Hall B is planning
the path forward on the use of the solenoid safety system, they
may be switching to a logic based (either cRIO or PLC) system and
they will inform the DSG of results of the decision in the future.
In the mean time the DSG will come up with a cost estimate to
upgrade the current solenoid controls, and a plan to integrate it
into the gas system controls to provided monitoring.
<br>
<br>
Thanks,
<br>
Marc
<br>
On 5/25/2017 12:04 PM, Ed Folts wrote:
<br>
<blockquote type="cite">Thanks you all for including me in the
loop. I think it is a great idea to build an updated version of
this control box. Having said that it must comply with the rules
for non UL tested components as called out in EHS&Q manual
chapter 6200. I have talked to Chris Cuevas and has agreed to
have his group do the certification inspection. In order for him
to do that he will need to be kept in the loop of fabrication
beginning with the schematics. The fabrication should be
supervised if not accomplished by a qualified electrical worker.
<br>
<br>
thanks again
<br>
<br>
Ed
<br>
<br>
<br>
On 5/24/2017 9:45 AM, Brian Eng wrote:
<br>
<blockquote type="cite">While I haven't looked at it in depth,
off-hand I don't think we need to change the design; if it
worked for CLAS6 that should be enough validation that the
system is sound.
<br>
<br>
What does need to be changed is the implementation: not having
any wiring outside of the chassis itself, replacing grommets
with connectors, adding serviceable fusing, and small things
like switching from lamps to LEDs, etc.
<br>
<br>
We'll start putting together a parts list for the new system.
<br>
<br>
<blockquote type="cite">On May 23, 2017, at 7:09 PM, Amrit
Yegneswaran <a class="moz-txt-link-rfc2396E" href="mailto:yeg@jlab.org"><yeg@jlab.org></a> wrote:
<br>
<br>
marc,
<br>
with regards to §2, highlighted, after much deliberation, i
am of the opinion that because of the exigent circumstances,
cosmic tests and noise source debugging, replacing the
underrated cable with a cable of adequate rating, was the
right thing to do. however, i am concerned about the
compliance of this old system with current safety
requirements. one definitely does not want to encounter
hitherto unknown problems. so, notwithstanding the
circumstances, the system needs to be replaced as soon as
possible.
<br>
<br>
as we discussed at the meeting today, dsg could build a
safety system to replace the existing system; hall b
technicians could run the new cables (if needed).
<br>
<br>
brian, please discuss the matter with george and come up
with a design; mindy will fabricate the needed parts, which
marc and george can install. brian, george, and marc please
provide a cost estimate for the new system.
<br>
<br>
amrit
<br>
<br>
From: "Marc Mcmullen" <a class="moz-txt-link-rfc2396E" href="mailto:mcmullen@jlab.org"><mcmullen@jlab.org></a>
<br>
To: "dsg-dc" <a class="moz-txt-link-rfc2396E" href="mailto:dsg-dc@jlab.org"><dsg-dc@jlab.org></a>
<br>
Sent: Tuesday, May 23, 2017 5:11:40 PM
<br>
Subject: [Dsg-dc] DC gas safety system
<br>
<br>
Hi Morgan,
<br>
<br>
Brian and I have replaced the 24VAC source cables which run
from the
<br>
SFL3 gas safety system box, to the distribution box (small
one with the
<br>
barrier blocks). We have also removed the bad barrier block
from the
<br>
distribution and relocated the R1/2 solenoid power wires to
the single
<br>
barrier block.
<br>
<br>
Brian calculated the total draw of the solenoids to be just
under 6amps
<br>
for R1/2, the new cable p/n rates it at 15A vs. 4.9A (rating
for 18awg
<br>
cable, which was replaced).
<br>
<br>
We tested the solenoids with the safety system box in local
mode. All
<br>
were audibly verified. We left the supply flow at 0Lpm, as
you requested.
<br>
<br>
Thanks,
<br>
<br>
-- <br>
Marc McMullen
<br>
Detector Support Group
<br>
757-269-7738
<br>
</blockquote>
</blockquote>
<br>
<br>
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<br>
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<br>
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<br>
</blockquote>
<br>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
George Jacobs
Jefferson Lab (TJNAF)
STE 12
12000 Jefferson Ave.
Newport News, VA 23606
(office) 757-269-7115
(cell) 757-876-0480
(email) <a class="moz-txt-link-abbreviated" href="mailto:jacobsg@jlab.org">jacobsg@jlab.org</a>
(website) <a class="moz-txt-link-freetext" href="https://userweb.jlab.org/~jacobsg">https://userweb.jlab.org/~jacobsg</a></pre>
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