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#1 Posted : 27 November 2001 11:34:00(UTC)
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Posted By Andrew Powell I am in the final stages of purchasing new BA sets, facemask/filter sets and suits as part of our ammonia plan. A Rep recently told me that an ammonia filter might only last a few seconds if the concentration of ammonia is high. I plan to set an escape scenario to confirm the maximum escape times, but I need help obtaining breakthrough times for the various ammonia filters that are available. I need to know if filters alone will give them enough time to ESCAPE ONLY in case of an ammonia leak or if we should be purchasing “a 10 minute escape set” as well. Should they need to re-enter they will be wearing full BA and suits, the filter would be for escape situations only. Thanks and regards Andrew
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#2 Posted : 27 November 2001 13:36:00(UTC)
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Posted By Robert K Lewis You don't indicate the likely maximum levels that could be expected. My general advice is to forget the filters. 10 min sets are useful but ensure that it has full head covering. I would be concerned that with high ammonia levels possible that even this may not prevent serious injury unless body, hand and leg protection was already being worn. I well remember sampling ammonia spheres, the gas can find every pinprick hole and react with body moisyture giving some quite severe burns. Bob
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#3 Posted : 27 November 2001 13:56:00(UTC)
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Posted By Andrew Powell Thanks for the advice Bob much appreciated. I am talking about an escape of ammonia/failure of a valve etc in a semi-confined space (due to the access) not area. Specifically roof voids, where our engineers spend time servicing electric’s and the boiler/heater system etc. Am I right in thinking that the concentration would vary depending on the location and the nature of the fault, size of leak etc. Unfortunately I have no data to go on. We would have to create the conditions, but can they be successfully re-created with accuracy and safety ?? I have to recommend suitable protection but this has to be such that it will be used 100%. It would be impractical and probably unenforceable to insist on full BA and suits when completing minor electrical work and knowing that leaks are extremely unlikely. The “10 minute set” I have looked at is a Drager set, complete coverage of head. It has good shelf life and can be used instantly, (if you believe the sales pitch) Thanks again, Regards Andrew
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#4 Posted : 28 November 2001 09:29:00(UTC)
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Posted By Robert K Lewis Is there any way to provide a secondary containment around the valves and likely fail points. In a confined space and assuming an anhydrous gas you could achieve a % range in some areas and these are definitely likely to cause burns. Please note that it is the eyes and genital areas that will feel these effects most of all. Whatever you do get the plan in writing and regularly rehearse the escape process in the actual area to ensure rapid, almost automatic response. Don't forget pre-entry checks on the escape kit. Bob
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#5 Posted : 28 November 2001 16:16:00(UTC)
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Posted By Brian Houghton Andrew, I am not qualified to advise on this, though it does make sense that filter breakthrough could be very rapid if concentration is very high. I have found 3M very helpful for technical advice in the past. They have a telephone helpline no. 0870 60 800 60. They may be able to assist you. Regarding your previous response, I imagine that keeping the genital area covered would provide a partial control measure in this respect. Regards, Brian
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