[Dsg-ltcc] stop gas flow?

[Maurizio Ungaro]

Good morning George,

Would it be possible to stop the flow of gas until the detector pressure falls below 1" of water (or another value you think it's better). If it reaches that pressure than we can start filling it up again.

This way we would reduce greatly the losses due to atmospheric variations, that seems to be the most cause of gas losses.

If you think that's feasible, let's do it. Otherwise it may be better to just continue the gas flow as it is now.

Thanks,

Mauri

> On Mar 9, 2018, at 3:19 PM, George Jacobs <jacobsg at jlab.org> wrote:
> 
> Hi Stepan,
> 
> The only way to keep the window inflated is to flow gas. We could switch to N2 to maintain sufficient pressure to maintain window shape. But, that may result in an increase is gas C4F10 loss during during N2 flow operation and again during the later "topping off" process. Since we have not done this before, there is no reference to point to. It does add an additional layer of complexity to the activity.
> 
> George
> 
> On 3/9/2018 2:54 PM, Stepan Stepanyan wrote:
>> George,
>> 
>> Thanks for the details. Yes, it seems not much can be saved, but anything we can save is a plus. 
>> Of course we cannot allow window come down on mirrors. In that respect, is there a option to reduce the loss?
>> 
>> Regards, Stepan
>> 
>> 
>>> On Mar 9, 2018, at 2:23 PM, George Jacobs <jacobsg at jlab.org <mailto:jacobsg at jlab.org>> wrote:
>>> 
>>> Ho Mauri,
>>> 
>>> An additional 2 weeks of running  will result in a decrease of ~7 kg gas from the supply tank, assuming 0.5kg per day usage.
>>> 
>>> Currently, ~56 kg C4F10 remains in the supply tank. This is a 112 day supply assuming 0.5 kg per day usage.
>>> 
>>> So, if we do nothing, in 2 weeks there will be ~49 kg C4F10 remaining in the tank. No change in detector pressure. Same as now.
>>> 
>>>  If we do turn it off, there will be ~56 kg remaining in the tank when we restart flow. Detector pressure and fill will be reduced due to gas leakage and the loss from ambient pressure changes during the outage. The detector will need to be "topped off" once we turn the gas back on. This will require X amount of gas. Since X is unknown, but most likely X < 7 kg and most definitely X > 0, the amount of gas saved will definitely be < 7kg. So, we do not know how much gas  this will actually save. Once gas flow is restarted, it may require 1-2 days to refill. My only real concern is if the window deflates to the point were it contacts and applies pressure to the mirrors. That would be bad
>>> 
>>> I do not see much of a savings or advantage in turning it off. But, that's not my call, it's yours. We can turn gas flow off if you want it off. Let me know what you decide. We will need to turn the gas off at the supply tank.
>>> 
>>> Cheers,
>>> George
>>> 
>>> On 3/9/2018 11:03 AM, Maurizio Ungaro wrote:
>>>> Hi George,
>>>> 
>>>> We'll have a downtime in accelerator that may run for a couple of weeks.
>>>> 
>>>> In the spirit of saving as much gas as possible, what are our options?
>>>> 
>>>> Thanks,
>>>> Mauri
>>>> 
>>> 
>>> -- 
>>> George Jacobs
>>> Jefferson Lab (TJNAF)
>>> STE 12
>>> 12000 Jefferson Ave.
>>> Newport News, VA 23606
>>> 
>>> (office) 757-269-7115
>>> 
>>> (cell)   757-876-0480
>>> 
>>> (email) jacobsg at jlab.org <mailto:jacobsg at jlab.org>
>>> 
>>> (website) https://userweb.jlab.org/~jacobsg <https://userweb.jlab.org/%7Ejacobsg>
> 
> -- 
> George Jacobs
> Jefferson Lab (TJNAF)
> STE 12
> 12000 Jefferson Ave.
> Newport News, VA 23606
> 
> (office) 757-269-7115
> 
> (cell)   757-876-0480
> 
> (email) jacobsg at jlab.org <mailto:jacobsg at jlab.org>
> 
> (website) https://userweb.jlab.org/~jacobsg <https://userweb.jlab.org/~jacobsg>
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