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Subject: Re: [DCHAS-L] PNNL Hydrogen Fire Event Video

Date: Jan 29, 2019 15:37 UTC

Author: Eugene Ngai <eugene_ngai**At_Symbol_Here**COMCAST.NET>

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Subject: Re: [DCHAS-L] PNNL Hydrogen Fire Event Video

Date: Jan 29, 2019 17:16 UTC

Author: Kucharski, Timothy <timothy.kucharski**At_Symbol_Here**ARAMCOSERVICES.COM>

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From: Ken Kretchman <kwkretch**At_Symbol_Here**ncsu.edu>

Subject: Re: [DCHAS-L] PNNL Hydrogen Fire Event Video

Date: Jan 29, 2019 16:36 UTC

Reply-To: ACS Division of Chemical Health and Safety

In-Reply-To: Re: [DCHAS-L] PNNL Hydrogen Fire Event Video

Demystify: 

Yes....we require these from our gas vendor for flammable and toxic gases.. Invented for this application at IBM Research in the early 80s as
Eugene mentions. We used a 0.006 mil orifice back then for 100 gram silane cylinders. Few lab processes require flow rates
in excess of what can be delivered through these.these which come in various sizes.

Ken.


Ken Kretchman, CIH, CSP Director, Environmental Health and Safety
NC State University / Box 8007 / 2620 Wolf Village Way / Raleigh North Carolina 27695-8007
Email: Ken_Kretchman**At_Symbol_Here**ncsu.edu / Phone: (919).515.6860 / Fax: (919).515.6307


On Tue, Jan 29, 2019 at 11:21 AM Eugene Ngai <eugene_ngai**At_Symbol_Here**comcast.net> wrote:

What Ken is referring to are RFO (Restrictive Flow Orifices), these were designed in the 1980's to be installed in the cylinder valve outlet. Initially a 0.010" was used to prevent silane from being released without immediate ignition. It continues to be used today for cylinders of silane. To comply with the Fire Code requirements for worst case releases, many users use a 0.006" RFO for highly toxic gases such as arsine or phosphine to reduce the size of the abatement system. There are many other sizes available. Ken's boss David Rainer wrote an excellent AIHA article on the origin and use of RFO's. If you want a copy please e-mail me

In addition lecture bottles (LB) have lecture bottle valves and CGA connections 160 or 170). These cannot have RFO=E2=80™s inserted. Lecture bottles that have standard cylinder valves and PRDs are called 7X cylinders. These can have RFO's inserted

Eugene Ngai

Chemically Speaking LLC

www.chemicallyspeakingllc.com