[labnetwork] Paging system

[Iulian Codreanu]

Thank you very much John!  As usual, very useful information coming from 
you!

iulian Codreanu, Ph.D.
Director of Operations, UD NanoFab
University of Delaware
Office: 163 ISE Lab
Mail to: 250N ISE Lab
Ship to: 165 ISE Lab
221 Academy Street
Newark, DE 19716
302-831-2784

On 10/28/2014 10:47 AM, John Shott wrote:
> Iulian:
>
> I've dug up our Sound Level Meter (the best that Radio Shack has to 
> offer ...) and have made a few measurements to provide you with some 
> example numbers.  Note: my measurements were made using the dB(C) 
> frequency compensation ... although I will give you a couple of 
> references using dB(A) frequency compensation.
>
> In general, clean rooms are pretty noisy.  Just the noise of the air 
> handling equipment can be significant.  In fact, about 3 years ago we 
> dropped our mean vertical air velocity from about 90 to about 70 feet 
> per minute.  At the time, everyone commented on the fact that it was 
> quieter in the clean room.  That said, even with lower air velocities, 
> I could only find one area of our lab that had a reading of less that 
> 60 dB(C).  That was the room in which our Raith 150 ebeam tool is 
> located and it registered 53-55 db(C).
> The next two quietest rooms were an in-process measurement room (AFM 
> and friends) coming in at about 60 db(C) and our gowning room at 61-62 
> db(C) and there is essentially no noisy equipment in either of those 
> rooms.
>
> Most areas of the lab with "real" process equipment in them registered 
> in the range of 69-72 dB(C).  Note: most, but not all, of our pumps 
> actually live in the sub-fab.  However, there are enough in-tool and 
> near-tool pumps, fans, and other noise generators to increase sound 
> levels significantly.
>
> The two loudest areas of our lab are near a bank of LPCVD tubes that 
> have their pumps in the cabinet, rather than in the sub-fab. There we 
> measured sound levels of 79-80 db(C).  Even though the pumps for our 
> AMAT Centura epi reactor are in the sub-fab, sound level readings near 
> that tool are about 74-76 dB(C).
>
> Note:  our sub-fab is quite noisy with peak readings of about 86 dB(C) 
> near the big scrubbers with average readings down there of about 82-83 
> dB(C).
>
> In areas dominated by equipment noise (which is most places in the 
> clean room) and certainly in the sub-fab, I found that dB(A) readings 
> were only about 2 dB lower than db(C) readings due to the fact, I 
> suspect, that the noise of pumps and motors is dominated by 
> higher-frequency components.  In an area with less equipment noise, 
> however, I found that dB(A) readings were about 5 dB lower that the 
> dB(C) reading at that location.
>
> While I expect that there is significant variation from lab to lab in 
> these numbers with, I suspect, newer labs being somewhat quieter, I 
> think that it is reasonable to design for an average background sound 
> level of about 70  dB(C) with some areas closer to equipment probably 
> reaching as high as 80 dB(C).
>
> As a bit of corroborating evidence, I believe that the folks who had 
> tried to do various forms of video training and collaboration have 
> found that using headphones and a microphone produce more 
> understandable communication than relying on "field microphones".
>
> Finally, we clearly did not spend much on our "sound level 
> instrumentation package" ... in fact, while I haven't compared 
> performance, I think that there are a collection of free apps for 
> smart phones that are probably just as suitable for spot checks.
>
> Let me know if you have any further questions,
>
> John
>
> On 10/24/2014 10:41 AM, Iulian Codreanu wrote:
>> Dear Colleagues,
>>
>> I would like to not allow cell phone use in the Delaware cleanroom; I 
>> recall a long thread on this forum with various opinions on this 
>> topic.  Since I would very much like for my customers to be in touch 
>> with the outside world while in the cleanroom, I have been trying to 
>> develop a paging system that would work with the VOIP phone system.
>>
>> The many pieces of the puzzle are coming together but I am struggling 
>> answering a basic question posed by the "speaker guy": how noisy will 
>> your cleanroom be?  That's a tough one because I will not know for a 
>> number of years until the cleanroom is filled with equipment.
>>
>> I would like to get an idea of how noisy fully operational cleanrooms 
>> are (both the bay and chase areas).  Would you please share your 
>> knowledge?
>>
>> Thank you very much!
>>
>> Iulian
>>
>
>
>
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