[Dsg-halla_gas] [EXTERNAL] Re: GEM gas distribution test setup

Mon Jan 4 10:59:21 EST 2021

Hi George,

I was referring to the flow meters in the new gas panel. The ones we have
in the EEL clean room are quite good and we are satisfied with them. I'm
attaching picture of those flow meters we have in the cleanroom in case you
can find them and replace them with the ones installed in the gas panels.
 I think the sensitivity of the flow meters wasn't really an issue. This
small flow rate it only to flush the GEMs to prevent humidity getting in
and when taking data, we will use a higher flow rate of 225 cc/min.

Best
Anu

On Mon, Jan 4, 2021 at 10:47 AM George Jacobs <jacobsg at jlab.org> wrote:

> I have a question. When you say " the main issue with the current flow
> meters have been their high sensitivity to the turning knob making it
> difficult to set the flow meters to small values like 75 cc/min."
>
> Are you referring to the flow meters currently in the clean room, or the
> ones on the new gem gas  panel?
>
> Rotometers are available in many configurations. Unfortunately, there are
> limitations on having high accuracy at very low flows while still having
> the ability to set a high flow. While the Dwyer made  RMA series flow meter
> is small and inexpensive, it's accuracy is only within the stated range of
> the flow meter. 50-500 sccm and 100-1000 sccm N2. While this is a
> limitation of the rotometers, the mass flow transducers do not have this
> low flow limitation. You would need a laptop with the transducer readouts
> to set flows below the scale of the rotometer. Below 50 sccm and 100 sccm
> respectively. You will want to do this anyway if you want to precicely
> match the flow rates to the GEMS.
>
> Thanks,
> George
>
> --
> George Jacobs
> Jefferson Lab (TJNAF)
> STE 12
> 12000 Jefferson Ave.
> Newport News, VA 23606
> (office) 757-269-7021
> (email) jacobsg at jlab.org
> (url) https://userweb.jlab.org/~jacobsg
>
>
> ------------------------------
> *From:* Dsg-halla_gas <dsg-halla_gas-bounces at jlab.org> on behalf of
> Anuruddha Rathnayake <adr4zs at virginia.edu>
> *Sent:* Monday, January 4, 2021 10:24 AM
> *To:* Marc Mcmullen <mcmullen at jlab.org>
> *Cc:* dsg-halla_gas at jlab.org <dsg-halla_gas at jlab.org>
> *Subject:* Re: [Dsg-halla_gas] [EXTERNAL] Re: GEM gas distribution test
> setup
>
> Hello Marc and Chuck,
>
> I was in communication with Kondo and he said that the usual operational
> flow rate of a GEM module that we have will be 225 cc/min whereas the max
> flow rate we will go would be 300 cc/min.  (The 75 cc/min flow rate is for
> the "idling" state where we just flow Nitrogen to prevent any humidity
> getting in to the cambers/modules)
>  Therefore, the flow meters we use should give us the opportunity to go
> slightly higher than 300 cc/min but probably it doesn't need to go as high
> as 500 cc/min as the ones we have right now in the gas panel.
> However, like Chuck said the main issue with the current flow meters have
> been their high sensitivity to the turning knob making it difficult to set
> the flow meters to small values like 75 cc/min.
>
> I'd be happy to participate in a bluejeans meeting to discuss the
> situation. However, I think Kondo will not be available as he's going to be
> on vacation.
>
> Best
> Anu
>
>
>
> On Mon, Jan 4, 2021 at 9:26 AM Marc Mcmullen <mcmullen at jlab.org> wrote:
>
> Hi Chuck,
>
> Thanks for the update. I will set up a bluejeans meeting this week so we
> can all discuss the situation concerning the panel. I have added this email
> thread to the mailing list (I added you before the holiday break), at this
> stage it is very important to that the DSG stay informed on the leak
> checking of this prototype to be able to make any changes necessary for the
> operational gas panels.
>
> Please let us know what the testing plans are as you proceed. This
> information will be informative to the group.
>
> Regards,
> Marc
>
>
>
>
> ------------------------------
> *From:* Chuck Long <mlong at jlab.org>
> *Sent:* Monday, January 4, 2021 9:07 AM
> *To:* Marc Mcmullen <mcmullen at jlab.org>
> *Cc:* Rathnayake, Anuruddha (adr4zs) <adr4zs at virginia.edu>
> *Subject:* Re: [Dsg-halla_gas] [EXTERNAL] Re: GEM gas distribution test
> setup
>
>  Hi Marc,
>
>  We have assembled an independent 4-way manifold in order to flow gas over
> the holiday, we are still using the panel flowmeters.
>
>  Gas flow set at 75 cc/min results in the flowmeters being barely on and
> at the bottom of the scale. We can find out from Anu what the typical flow
> will be and specify the flowmeters with one that puts the setting in the
> middle of the range. (maybe higher quality ones with glass vials?)
>
>  We will plan to leak check the rack this week, still seems to be leaking.
> We have a method of using air with a trace amount of hydrogen that the leak
> testers are sensitive to. (Cylinder is actually there and available from
> the GRINCH leak testing).
>
>
> -Chuck
>
>
>
> ------------------------------
> *From:* Dsg-halla_gas <dsg-halla_gas-bounces at jlab.org> on behalf of Marc
> Mcmullen <mcmullen at jlab.org>
> *Sent:* Wednesday, December 23, 2020 1:54 PM
> *To:* Anuruddha Rathnayake <adr4zs at virginia.edu>
> *Cc:* dsg-halla_gas at jlab.org <dsg-halla_gas at jlab.org>
> *Subject:* Re: [Dsg-halla_gas] [EXTERNAL] Re: GEM gas distribution test
> setup
>
> Hi Anu and Chuck,
>
> When we get back from break, I'll discuss changing out the flow meter
> valves for a more sensitive range (maybe 0 to 100 sccm) with George and see
> what he advises.
>
> During your leak checking, can you make note of what tubing was changed
> out. We are keeping a record of issues with the system. I have provided a
> spread sheet with the two connection for each length of tubing. If you
> could put a yes or no in the indicated cell it would help us understand
> where the leaks are.
>
> If there are other leaks please feel free to expand the chart. Also
> pictures of the new tubing would help.
>
>   Manifold to Flow Meter Panel Flow Meter Panel to Gas Flow Sensor chassis
> Ch1
> Ch2
> Ch3
> Ch4
> Ch5
> Ch6
> Ch7
> Ch8
> Regards,
> Marc
> ------------------------------
> *From:* Anuruddha Rathnayake <adr4zs at virginia.edu>
> *Sent:* Wednesday, December 23, 2020 12:35 PM
> *To:* Marc Mcmullen <mcmullen at jlab.org>
> *Cc:* dsg-halla_gas at jlab.org <dsg-halla_gas at jlab.org>
> *Subject:* [EXTERNAL] Re: [Dsg-halla_gas] GEM gas distribution test setup
>
> Hi Marc,
>
> There has been several leaks in the gas pannel and Chuck replaced all the
> Nylon tubing with Poly Ethylene tubging today morning. Now we are flushing
> the system and planning to connect the GEMs in the afternoon, if there are
> no more issues.
>
> Best
> Anu
>
> On Wed, 23 Dec 2020, 11:24 Marc Mcmullen, <mcmullen at jlab.org> wrote:
>
> Hi Kondo,
>
> I was just checking to see if there was an update on the test setup and if
> there are plans to flow gas during the holiday break.
>
> Regards,
> Marc
> _______________________________________________
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>
>
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