Another nitrous oxide accident report

I expect we will hear within a month or two from the safety reviews for the Scaled accident that happened last July. It will be interesting to find out what conclusions they reached about the cause of the explosion. I posted previously a report (pdf) on a N2O tank rupture at a medical gas plant in Eindhoven, The Netherlands in 2001. Now someone has sent me a copy of a safety report on a N2O tank explosion that occurred during preparations for "testing an N2O-CO laser combustor" by Pratt & Whitney on July 6, 1973.

For the Eindhoven case, the explosive decomposition of nitrous oxide was attributed to auto-ignition after a "pump was running dry and became hot" (slide 21). For the Pratt & Whitney case, the ignition was caused when "hot (315F) ambient pressure nitrogen gas trapped" in a run line between two valves reached a 2050F after it was rapidly compressed from hot N2O suddenly released into it (see pp.8-10).

Posted 12/10/07 | 22:34:51 by TopSpacer | Filed under: Propulsion

Comments

"testing an [sic] N2O-CO laser combustor"

I think "an" is correct, because en-two-oh starts with a vowel. Acronyms that have a consonant first letter, but whose first letter has a vowel sound, should be proceeded by "an", like "an RCMP officer" (an are-sea-em-pea officer). Of course some acronyms like RADAR are pronounced as words rather than spelling them out, so that rule doesn't apply.

It all depends on how you pronounce the acronym. I read "an Isp of 250s" as "a specific impulse of 250 seconds" instead of "an eye-ess-pea of 250 ess", so I have to convert the "an" to "a" in my head, or else it doesn't work.

Posted by Ashley at 12/11/07 10:00:24

Hi Ashley,
When I first saw the "an N2O", it didn't look or sound right with "an". However, re-reading it and sounding it out, I think you are correct. I've now removed the [sic].
Thanks,
- Clark

Posted by TopSpacer at 12/11/07 11:19:12

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