[Dsg-rtpc] Summary of BoNuS target purge issues - March 17, 2020

[Sebastian Kuhn]

Thank you for the write-up. It mostly captures our issues, although I disagree with the statement

In reality, depending on the closing order of those three valves, there is enough line between the MFC and SVBT108 to where gas can still flow to pressurize the line between the target gas pad in the hall between the MFC and SVBT108).

as I have repeatedly explained before. *)

Regardless of the underlying issue, we will be awaiting detailed instructions on how to manually open the MFC valve to 100%. As your write-up points out, we can easily loose 45 min (3x(20-5)) during a regular daily target purge, and more than twice that during a target gas CHANGE (which requires 6 purge cycles) due to the difference between “fast fill” and “slow fill”. Even if we can only cut this time down by 40% (= the difference between 200 sccm and 330 sccm), this would potentially save 12 hours of beam time which will be in short supply once we come back up.

Thanks, and best greetings - Sebastian

*) For those new to this exchange: To sustain a REAL flow of 200 sccm, you need to have a significant reservoir of volume at different pressure on BOTH sides of the flow meter (to flow FROM and to flow INTO), not just on the downstream side (the hundreds of feet of gas line between pad and gas panel). If SVBT100 and 102 are closed (ignoring 108), then the UPstream volume is hardly more than a few 10’s of ccm (I estimate 30 ccm) so after a minute that volume would be totally depleted at 200 sccm.


On Mar 17, 2020, at 1:02 PM, Amrit Yegneswaran <yeg at jlab.org<mailto:yeg at jlab.org>> wrote:

excellent, tyler and brian

________________________________
From: Dsg-rtpc <dsg-rtpc-bounces at jlab.org<mailto:dsg-rtpc-bounces at jlab.org>> on behalf of Tyler Lemon <tlemon at jlab.org<mailto:tlemon at jlab.org>>
Sent: Tuesday, March 17, 2020 12:58 PM
To: dsg-rtpc at jlab.org<mailto:dsg-rtpc at jlab.org> <dsg-rtpc at jlab.org<mailto:dsg-rtpc at jlab.org>>
Cc: Patrizia Rossi <rossi at jlab.org<mailto:rossi at jlab.org>>
Subject: [Dsg-rtpc] Summary of BoNuS target purge issues - March 17, 2020

Hello,

Attached is a summary of the issues discussed over email yesterday and today for the BoNuS target purging.

Best regards,
Tyler
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