Just a clarification on the RFO for silane. During the 1970' and 1980's there were numerous accidents with silane because it can easily be released without immediate ignition. During this time there were 4 fatal gas cabinet explosions. IBM funded numerous studies and hosted many safety seminars on silane. The development of the RFO was an attempt to increase the probability of immediate ignition as well as reduce the worst case release rate. In my article on silane without an RFO the flame is 3 m while with a 0.010 RFO it is 0.5 m. FM Global in the 1990=E2=80™s conducted extensive gas cabinet testing with silane for SEMATECH. Dr. Taminini determined that if the exhaust ventilation rate is 250 times the flow rate from an RFO, the deflagration would pop the gas cabinet door rather than violently rip it apart. This is why CGA G-13 requires a exhaust flow rate of 250 times RFO for silane gas cabinets. The worst silane gas cabinet explosion that I investigated was the one in 2007 in India. The gas cabinet exhaust was inadequate and the cylinder had no RFO. The explosion cause the gas cabinet window to sever the operators head and the door picked up his body propelling it across the room shattering a brick wall.

To give you an idea as to the power of silane

I was test director for the silane release testing in New Mexico in 2010 and 2011 to develop data to rewrite CGA G-13. In one of the test we discharged through a =BD" dia tube silane at a pressure of 1.200 psig. This was directed at an array of cylinders 6" from the outlet. There was a lit cigarette behind the cylinders. This simulated an open air obstructed release with promoted ignition. The overpressure we measured at 12' exceeded 18 psig (fatal). Inside a building the overpressure would have be magnified. I investigated an incident in 2014 involving 6 gms of a silane compound that blew the gas cabinet apart and severed a cylinder rack in front of it. The force propelled 6 large cylinder across the room. Fortunately the building had roof mounted blow out panels that relieved the overpressure.

Some research articles that I coauthored on silane based on numerous projects

1. Ngai, E.Y., Chen, J. R., Huang, P. P., et al,"Experimental Studies on the Ignition Behavior of Pure Silane Released into Air", Journal of Loss Prevention in the Process Industries, July 2009
2. Ngai, E.Y., Chen, J. R., Huang, P. P., et al, "Ignition Characteristics of Steady and Dynamic Release of Pure Silane into Air", Combustion, Explosion and Shock Waves Vol.. 46, No. 4. July 2010, pp. 391-399
3. Ngai, E., Chen, J.R. , et al, "CGA G-13 Large-Scale Silane Release Tests - Part I. Silane Jet Flame Impingement Tests and Thermal Radiation Measurement", Tenth International Symposium on Hazards, Prevention, and Mitigation of Industrial Explosions, Bergen, Norway, 10-14 June 2014
4. Ngai, E., Chen, J.R. , et al, "CGA G-13 Large-Scale Silane Release Test -Part II. Unconfined Silane-Air Explosions", Tenth International Symposium on Hazards, Prevention, and Mitigation of Industrial Explosions, Bergen, Norway, 10-14 June 2014
5. Ngai, E. Y., Fuhrhop, R., Chen, J. R.*, Chao, J., Bauwens, C. R., Mjelde, C., Miller, G., Sameth, J., Borzio, J., Telgenhoff, M.. Wilson, B., CGA G-13 Large-Scale Silane Release Tests - Part I. Silane Jet Flame Impingement Tests and Thermal Radiation Measurement, Journal of Loss Prevention in the Process Industries, Vol 36, July 2015, pp 478-487
6. Ngai, E.Y., Fuhrhop, R., Chen, J. R.*, Chao, J., Bauwens, C. R., Mjelde, C., Miller, G., Sameth, J., Borzio, J., Telgenhoff, M. Wilson, B., CGA G-13 Large-Scale Silane Release Tests - Part II. Unconfined Silane-Air Explosion, Journal of Loss Prevention in the Process Industries, Vol 36, July 2015, pp 488-496
7. Ngai, E., Chen, J.R , Tsai, H.Y. et al, Unconfined Silane-Air Explosions, 11th International Symposium on Hazards, Prevention and Mitigation of Industrial Explosions, Dalian, China, July 24-29, 2016

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 Ken Kretchman
Sent: Tuesday, January 29, 2019 11:36 AM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: Re: [DCHAS-L] PNNL Hydrogen Fire Event Video

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'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

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 Mon, Jan 28, 2019 at 10:10 PM jeskiekb**At_Symbol_Here**comcast.net <jeskiekb**At_Symbol_Here**comcast.net> wrote:

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.

Kim

Sent from my Verizon LG Smartphone

------ Original message------

From: Schroeder, Imke

Date: Mon, Jan 28, 2019 1:12 PM

To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU;

Cc:

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

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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