[Dsg-rich] MVT exhaust fan in EEL 124

Wed Oct 18 12:28:33 EDT 2017

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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