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'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
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU> On Behalf Of Richard Palluzi
Sent: Tuesday, January 29, 2019 10:16 AM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: Re: [DCHAS-L] PNNL Hydrogen Fire Event Video
You need to be very careful as the flow limiting orifice supplied in most commercial cylinders, while limiting vs. a fully open valve, still allows an awful large flow which is more than usually required for research purposes. Installing a custom sized flow limiting restrictive orifice (available from Swagelok among others) is usually more prudent.
Richard Palluzi
PE, CSP
Pilot plant and laboratory consulting, safety, design,reviews, and training
Linkedin Profile
Richard P Palluzi LLC
72 Summit Drive
Basking Ridge, NJ 07920
rpalluzi**At_Symbol_Here**verizon.net
908-285-3782
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU> On Behalf Of Ken Kretchman
Sent: Tuesday, January 29, 2019 8:31 AM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: Re: [DCHAS-L] PNNL Hydrogen Fire Event Video
Depending on flow rates required..obtaining flammable and/or toxic gas cylinders with flow limiting orifices is also a good practice.
Ken Kretchman, CIH, CSP Director, Environmental Health and Safety
NC State University / Box 8007 / 2620 Wolf Village Way / Raleigh North Carolina 27695-8007
I'm going on memory from a couple of investigation updates that I've seen, but I think the answers are (1) There was heat and smoke detection in the room, not in the exhaust line for the hood. The temperature increase in the room was close to activating the sprinkler system, but did not get there. (2) They had pressure reducers in the line, but the flow into the controllers was still more than they needed. They are now looking at auto-shut-offs based on the flow rate being higher than it should be.
Sent from my Verizon LG Smartphone
Thank you, Robin, for sending this around. What surprised me about the video is the absence of a fire alarm, potentially a f ire suppression system, and an automatic gas shut off for these types of experiments that could be triggered either by heat/infrared. I wonder whether that exists.
Imke
From: ACS Division of Chemical Health and Safety > on behalf of "Robin M. Izzo" >
Reply-To: ACS Division of Chemical Health and Safety >
Date: Monday, January 28, 2019 at 9:08 AM
To: >
Subject: [DCHAS-L] PNNL Hydrogen Fire Event Video
My colleague at the Princeton University Plasma Physics Lab (a DOE facility) sent me this video from the Safe Conduct of Research (SCoR) at the Pacific Northwest National Lab (PNNL). There was a hydrogen fire and explosion in one of their fuel cell research labs in September 2018. This video highlights their incident investigation and lessons learned, and provides a good example of why it is necessary to continue to question and improve safety even for operations that have remained unchanged for many years with no serious incidents. This video is very well done and very much appreciated.
https://youtu.be/K7nf0hdHvMk
Best,
Robin
^^^^^^^^^^^^^^^^^^^^^^^^
Robin M. Izzo, M.S.
Director
Environmental Health and Safety
Princeton University
609-258-6259 (office)
609-865-7156 (mobile)
Visit the EHS website at ehs.princeton.edu and the Emergency Management website at emergency.princeton.edu
(she/her/hers)
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