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Previous by Date: Subject: Re: [DCHAS-L] Handling O2 and H2 Date: October 18, 2012 3:51:59 PM EDT Author: Laurence Doemeny |
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In addition to shifting risks, you are also shifting costs. It makes little economic sense to have a $25,000 electrolysis unit for each user, so centralized
gas distribution lines come into play. My campus hydrogen fuel-cell research building has such an arrangement, designed by licensed engineers and approved by the Office of the State Engineer, who is responsible for life safety issues in all state buildings.
The same engineers did the installation and helium leak-testing. The system included hydrogen gas sensors in every lab that used hydrogen, and in the utility chases. The sensors generated signals to valves that would turn off the flow and send a signal
to the fire alarm control panel with decision points at 25 and 37.5% of flammability limits. PI has a flow meter with totalizer serving his or her labs to compute the monthly hydrogen usage for billing purposes. I cannot remember the cost from the design
stage, but I think it was $350,000 plus or minus 50%
The users in the building opted not to buy a hydrogen generator because we have occasional power outages and their experiments cannot handle a hydrogen outage.
There are many long-term experiments (12-24 months) that are designed to test the ruggedness and longevity of fuel cell components and the loss of hydrogen means the experiment must be restarted. Fuel-cell researchers are not heavy users of hydrogen, but
they need good purity and consistent supply, so the building is fed by a multi-cylinder manifold.
There is a second hydrogen research building in the state in a locale governed by different fire codes than at the University but it uses nearly identical technology
for hydrogen distribution.
--------------------------------------------------------
Scott Goode, Professor
Department of Chemistry and Biochemistry
University of South Carolina
631 Sumter Street
Columbia SC 29208
Email: Goode**At_Symbol_Here**sc.edu
Phone: 803-777-2601
Fax: 803-777-9521
From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU]
On Behalf Of Daniel Crowl
Sent: Thursday, October 18, 2012 9:06 AM
To: DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Subject: Re: [DCHAS-L] Handling O2 and H2
Hi All,
You need to be careful that you don't shift the risk to somewhere else.
This new device will have a pressure and electrical hazard. For cylinders the cylinders are recertified once every five years by the supplier. For a lab process such as this, I believe it would need to be pressure certified annually by
a certified pressure testing facility.
I'm sure there are also cleaning and maintenance issues with this also.
I know that there is always a tendency to see that the grass is greener on the other side of the fence.
It's not completely clear to me where the risk and costs issues are on these two methods.
Dan Crowl
Michigan Tech
On Thu, Oct 18, 2012 at 6:21 AM, Jeskie, Kimberly B. <jeskiekb**At_Symbol_Here**ornl.gov> wrote:
Neal, we've used similar solutions for many years and most people like them. Generally, there are a few barriers that come up. Sometimes they can be dealt with, sometimes not:
1) purity or flow-some applications need one or the other that they don't believe the units can provide. Often, they are wrong.
2) mixing -depending on the application and risk profile, it might just be a better idea to buy premixed.
3) return on investment - sometimes it's hard to sell this concept if the ROI is out several years. The higher flow rate units can be more pricy.
My personal opinion - they are so worth it. Eliminating the labor and physical hazards from lugging the cylinders around and getting within building code limits for flammable gases tips that ROI scale.
Kim
Kimberly Begley Jeskie, MPH-OSHM
Physical Sciences Directorate Operations Manager
Oak Ridge National Laboratory
Office: (865)574-4945
Cell: (865)919-4134
-----Original Message-----
From: Neal Langerman [neal**At_Symbol_Here**CHEMICAL-SAFETY.COM]
Sent: Thursday, October 18, 2012 06:07 AM Eastern Standard Time
To: DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Subject: [DCHAS-L] Handling O2 and H2
Labs tend to have cylinders of H2 and O2 which pose risks that can be easily mitigated by reducing the quantity of gas. For the
researcher, all that is needed is a reliable gas source of sufficient volume and pressure to do the job. For the risk managers, the issue adds reducing the risk along with meeting the research needs. One proven way to do this is to generate O2
and/or H2 locally via the electrolysis of water.
I am looking at a resource that will deliver either or both gases at a pressure of about 1500 psi (100 bar) and a volume of 1 liter per minute (that
is a lot!).
It is locally generated and a simple power interruption removes the hazards associated with each gas.
So, my questions to the list are simple -
Is this of interest to you?
Is $25k USD reasonable to replace all of the H2 (or O2) cylinders in the chemistry department?
The big downside of this is having a single source within a department. Major research departments will likely want several. A look at the demurrage
costs of cylinders will easily make the $25k ( and low annual maintenance) seem reasonable.
I look forward to your comments and questions…
Incidentally, I do not have any financial involvement with the above; it was presented to me as a solution to a problem I have worked on for years –
too damn many cylinders in labs….
Neal
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