[labnetwork] H2 Generators

[Rizik]

The average cost runs about $6,500 per gas sensor including hardware,
programming, sensor, wiring, conduit, functional testing, commissioning,
etc. Pull Stations and horn/strobes each runs about $1,500 installed. 

 

You really got a point there. And yes, you will need to place gas sensors to
overlap in the area of work so that they will not miss a gas leak. Although
this is quite difficult to achieve, you try to install welded tubing from
the generator to the point of use then provide as sensor at each point.
Again, cost will be an issue. In a previous email, I mentioned that the gas
monitoring system shall be interlocked with the generator to ensure that it
shuts down upon gas detection, manual activation and fire alarm signal
initiation. 

 

One more item to consider, is installing an orifice in the tubing leaving
the generator to ensure that we do not allow more than 150% of the process
gas demand to be supplied to the tools. On past projects, we installed
excess flow mechanical valves that would trip if H2 flow rate exceeds a
preset limit. This will allow us to limit H2 leakage to a level that would
not exceed 25% of the LEL concentration in the lab space. All these
parameters MUST be taken in consideration by the engineer of record.
Occasionally, these parameters are overlooked and are only discovered during
the plan review cycle by the AHJ. 

 

Regards

 

Rizik Michael, PE

Principal

Integrated Engineering Services

Office: +408 261 3500, Ext. 201

Cell:      +408 718 0927

 

 

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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