[labnetwork] HPM gas survey

[Michael Khbeis]

Dear Colleagues,

Once again, I am pitted against my capital projects group. This time regarding HPM gas infrastructure. Thanks to your prior input, we were able to obtain a proper toxic gas monitoring system. However, now I am in a code interpretation debate with their process piping consultants on the use of VMBs for multi-tool feeds and coaxial lines. They don't want either in our project. They specified hastelloy for Chlorine and BCl3 but single walled 316ss (after much debate that 304 was not sufficient) for all our other gasses. In ALL my prior sites we always used coaxial lines as a secondary containment for HPMs, but currently this project has no coax specified. 

I am also in debate on whether or not 100% hydrogen (large 330cf cylinders) can be in the Cleanroom without a cabinet vs a bunker in a cabinet. Their interpretation is that an H-5 facility can store 9000cf; however, I believe they are ignoring the vented enclosure requirements. 

We will have the following HPM gasses:
100% Silane
100% Hydrogen
Ammonia
Chlorine
Boron Trichloride
Phosphine
Diborane

Can you please weigh in on your sites use of:

1) coaxial lines, which gasses and if any HPMs are excluded or use single hastelloy 

2) use of valve manifold boxes / vented enclosures for distributing HPMs to multiple tools (or anywhere else there's a mechanical connection)

3) location and enclosure or not for 100% hydrogen

And on a non-safety related note, we asked for panels with multi-stick feeds to each tool; however, the process piping designer just teed all of our lines from a single point and put a regulator at each tool instead to "save money". I am very concerned about LP gasses (e.g C4F8) being starved when multiple tools are running. We distinctly had issues with past lab with shared C4F8 bottles. Their recommendation is to ONLY heat the cylinder to increase vapor pressure, but given my limited knowledge, I believe with high flow rate and lacking heating of the panel and lines we will have gas condensation issues. To date, my input is still being dismissed so please state:

4) how you handle LP gas distribution to multiple tools 

I thank you so much for taking the time out of your busy schedules to provide this input. This community/forum has been such a blessing. 

Most gratefully,

Dr. Michael Khbeis
Washington Nanofab Facility
University of Washington
Fluke Hall, Box 352143
(O) 206.543.5101
(C) 443.254.5192
khbeis at uw.edu
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