[labnetwork] H2 Generators

[Abbie Gregg]

Pressure from hydrogen generators is low. Accidents I am aware of happened due to high hydrogen bottle pressure, and failure of regulator (if this happens, H2 can also very quickly go right through intact piping into the process tool and out the other end, causing a problem in the exhaust!). So speed/volume of gas escape is much less from a generator. A Valve Manifold Box can be used close but downstream of a generator for any distribution to multiple tools, and that is a place where excess flow sensing and leak detection around valves in an exhausted enclosure is possible. And you are not storing any hydrogen with a generator.

Abbie Gregg
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From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Grimard, Dennis
Sent: Wednesday, July 18, 2012 1:37 PM
To: labnetwork at mtl.mit.edu
Subject: [labnetwork] H2 Generators

All:

I have been watching the discussion regarding H2 generators.  Although I agree with most of what has been said I worry about being able to shut off the generator in case of a leak.  The generator does not know that it is delivering into a leak and unless the leak is detected then the generator will continue pumping to that leak.  Adding detectors is not the solution.  H2 detectors are difficult to place such that they will pick up a leak.  Do you add detectors at every possible leak point?  Add in the high velocities of the cleanroom and I hesitate to change from bottles to generators.

When considering the costs, you also have to consider the cost of the added detectors ... which are not cheap ...

Dennis Grimard, Ph.D.
Managing Director
Lurie Nanofabrication Facility
1246D EECS Blding
1301 Beal Avenue
Ann Arbor, MI 48109-2122
(734) 368-7172 Cell
http://www.lnf.umich.edu

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