[Dsg-rich] MVT exhaust fan in EEL 124
Valery Kubarovsky
vpk at jlab.org
Wed Oct 18 15:58:41 EDT 2017
Hello Amrit,
We consider all three items that you have suggested in your mail.
- We measure the temperature in all 138 FPGAs. The cabling will be redone.
It is not clear for a moment that it will remove all hot spots in epanel.
- I will appreciate if you will try to increase the air flow upto 1000 l/m !
- I like the idea with chiller. Do you have in mind what kind of chiller can we use?
I remember that we had one in the Hall for tagger chilling.
At the same time I want to test fans. The problem is too important and I want to test every possible way to decrease the front-end temperature. We don't need DSG support at this time for fans testing.
Regards,
Valery
> From: "Amrit Yegneswaran" <yeg at jlab.org>
> To: "dsg-rich" <dsg-rich at jlab.org>
> Sent: Wednesday, October 18, 2017 3:15:41 PM
> Subject: Re: [Dsg-rich] MVT exhaust fan in EEL 124
> hello everyone,
> in my opinion, fans will not help much.
> further, it is going to be a bear to put it together.
> 1. the length of the tubing has to be increased dramatically to exit the air
> beyond the FTOF
> 2. the fan has to be located somewhere.
> 3. the whole system has be be wired and installed in time.
> this is a "no-can-do" for DSG, as DSG does not have the manpower or the time.
> perhaps some one else (or group) can procure the fans and install it in time.
> my suggestions for the interim are:
> 1. redo the cabling so that it does not block the air-flow apertures.
> 1. measure the temperatures. (my guess is, it will be good. 250 watts is of the
> order of a powerful light) bulb. FPGAs typically work up to 85 C, no sweat!
> 2. increase the volume exchange of air,
> 1. by increasing the flow (flow can be increased to ~1000 l/m (500l/m per tube)
> 2. by increasing the size of the of the holes from 2 mm O.D. to 5 mm O.D.
> 3. if still unsatisfactory add a chiller (dew point for dry air is 70 C)
> amrit
> From: "Valery Kubarovsky" <vpk at jlab.org>
> To: "George Jacobs" <jacobsg at jlab.org>
> Cc: "dsg-rich" <dsg-rich at jlab.org>
> Sent: Wednesday, October 18, 2017 12:28:33 PM
> Subject: Re: [Dsg-rich] MVT exhaust fan in EEL 124
> Hi George,
> I want to notice that our electronic panel is not gas tight at all and has 6
> exhaust pipes in addition. It is not so easy to significantly increase the
> pressure inside. Nevertheless we are going to test what happens with the
> pressure system in the clean room
> - with 6 pipes but with/without fans connected
> - with fans ON/OFF
> When we tested the cooling system we did not notice any increase pressure in the
> main Cherenkov volume (with N2 gas).
> The cooling of the epanel is in a critical condition for a moment. It is the
> reason that we consider fans to help keeping front-end electronic at safe
> temperature. Several groups in CLAS12 are using similar technics (Forward
> tagger, SVT).
> Regards,
> Valery
>> From: "George Jacobs" <jacobsg at jlab.org>
>> To: "Valery Kubarovsky" <vpk at jlab.org>
>> Cc: "Tyler Lemon" <tlemon at jlab.org>, "dsg-rich" <dsg-rich at jlab.org>
>> Sent: Wednesday, October 18, 2017 9:36:06 AM
>> Subject: Re: [Dsg-rich] MVT exhaust fan in EEL 124
>> Hi Valery,
>> Have you looked at this scenario? Fan stops running during run. This would
>> result in an increased pressure in the electronics box. The increased pressure
>> increases the leak rate of cooling air into the RICH detector volume. Depending
>> on the severity of the leak, pressure in the RICH gas volume may increase until
>> the cooling system is turned off. The O2 concentration will increase until the
>> cooling flow stops. The O2 contamination then absorbs the light until it is
>> removed via N2 purge.
>> There is, of course, a worse case scenario, depending on how high the pressure
>> in the electronics box goes. Since final pressure is unknown, it may or may not
>> be a realistic failure mode.
>> So, perhaps a good question to answer would be; What are the advantages of using
>> the fan vs consequences of fan failure. Is adding a fan a good solution to your
>> problem or does it potentially create another problem?
>> George
>> On 10/17/2017 6:25 PM, Valery Kubarovsky wrote:
>>> Hi George,
>>> Thank you for looking to all these issues. I agree that we have to determine the
>>> exact location of these fans in the Hall-B and determine the change in the
>>> length of the exhaust tubes.
>>> And sure we will test the exhaust line pressure when the fans will be on and
>>> off.
>>> In any case the cRio interlock will monitor the temperature inside the
>>> electronic panel and will shut down the detecter in case of accident with
>>> exhaust fans.
>>> Thank you again,
>>> Valery
>>>> From: "George Jacobs" <jacobsg at jlab.org>
>>>> To: "Valery Kubarovsky" <vpk at jlab.org>
>>>> Cc: "Tyler Lemon" <tlemon at jlab.org> , "dsg-rich" <dsg-rich at jlab.org>
>>>> Sent: Tuesday, October 17, 2017 5:31:52 PM
>>>> Subject: Re: [Dsg-rich] MVT exhaust fan in EEL 124
>>>> Hi Valery,
>>>> Have you taken into account the length of the hose or tubing that must be added
>>>> in order to attach the fan to the detector? If the overall line length must be
>>>> doubled or tripled to reach the fan, the flow restriction from the tubing will
>>>> also double or triple.
>>>> If the fan stops running, the fan blades will restrict the gas flow at some
>>>> level. Flowing gas has velocity and momentum, fan blades will require the gas
>>>> change direction, loosing momentum and velocity.
>>>> So, there will be additional flow restriction and it will increase the cooling
>>>> air pressure in the electronics box in the case of fan failure. The added
>>>> restriction due to the additional lengths of tubing or hose can be calculated.
>>>> The additional restriction created by the fan blades can be physically tested
>>>> by turning off the fan and monitoring the change in the exhaust line pressure.
>>>> George
>>>> On 10/17/2017 4:27 PM, Valery Kubarovsky wrote:
>>>>> George,
>>>>> First we want to test it at the cleaning room to measure the effectiveness of
>>>>> these fans.
>>>>> And later on we will use it in the hall.
>>>>> The design of the cooling system was done without exhaust fans. In case of the
>>>>> power failure nothing will happen with the pressure system. The fan has much
>>>>> bigger diameter than our tubes and by this reason will not block the air flow.
>>>>> It is completely open.
>>>>> Regards,
>>>>> Valery
>>>>>> From: "George Jacobs" <jacobsg at jlab.org>
>>>>>> To: "Tyler Lemon" <tlemon at jlab.org> , "dsg-rich" <dsg-rich at jlab.org>
>>>>>> Sent: Tuesday, October 17, 2017 1:20:12 PM
>>>>>> Subject: Re: [Dsg-rich] MVT exhaust fan in EEL 124
>>>>>> Would this setup be used only in the clean room for testing or would this be for
>>>>>> use in the hall during normal operations?
>>>>>> If the answer is the latter, what would happen to air cooling flow and pressure
>>>>>> if the power to the fans tripped off during a run?
>>>>>> George
>>>>>> On 10/17/2017 11:56 AM, Tyler Lemon wrote:
>>>>>>> Hello Valery,
>>>>>>> Attached is the photo of the MVT exhaust fan in use in EEL 124.
>>>>>>> Would there be a possibility that RICH would use similar fans to pull out the
>>>>>>> hot air from the electronic panel?
>>>>>>> Best regards,
>>>>>>> Tyler
>>>>>>> _______________________________________________
>>>>>>> Dsg-rich mailing list Dsg-rich at jlab.org
>>>>>>> https://mailman.jlab.org/mailman/listinfo/dsg-rich
>>>>>> --
>>>>>> 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 (website) https://userweb.jlab.org/~jacobsg
>>>>>> _______________________________________________
>>>>>> Dsg-rich mailing list
>>>>>> Dsg-rich at jlab.org
>>>>>> https://mailman.jlab.org/mailman/listinfo/dsg-rich
>>>> --
>>>> 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 (website) https://userweb.jlab.org/~jacobsg
>> --
>> 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 (website) https://userweb.jlab.org/~jacobsg
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