Rank: New forum user 
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Hi, I'm based in a laboratory and have been asked to come up with a hazardous gas emergency plan. We're working with compressed acetylene, argon, argon/methane, oxygen, propane and air, all stored outside the building and piped in. I have a couple of questions, should we be looking at gas monitors covering the hazardous gases in case of leaks within the building? Also, without monitors in place, should a leak occur and we evacuate how do we assess when it's safe to return? Our safety team is a bit out of it's depth, so I'm on my own with this one, any help would be appreciated.
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Rank: Super forum user 
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With it being a piped supply it is likely someone from the vendor will have been involved at some stage to affirm the acceptability to off-load. They will likely have a strong technical team which can provide guidance at site and more beneficial insight in to how other sites are using similar piped supplies.
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Rank: Super forum user
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With it being a piped supply it is likely someone from the vendor will have been involved at some stage to affirm the acceptability to off-load. They will likely have a strong technical team which can provide guidance at site and more beneficial insight in to how other sites are using similar piped supplies.
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Rank: New forum user
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Thanks Roundtuit. I have reached out to them but as yet no response.
I'm thinking as the system has been in place for quite a few years it may be worth having them back on site anyway to complete an updated assessment of how we're using the gases, checking the regulators etc.
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Rank: Super forum user
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You would have to have a pretty major leak / small laboratory with poor ventilation before these gases became a problem. Argon naturally is about 0.93% concentration is air natually. Its an asphyxiant - but to displace that much oxygen before it becomes a problem takes some doing. O2 would have to be less than about 18% before of significant concern. Oxygen - again, already about 20% of air. To get oxygen enrichment you would need maybe 25% + before its potentially a problem. Propane - flammable - LEL 1.1% if I remember correctly - maintain good ventilation Argon/methane - what is the mix? Potentially flammable above 4-% LEL Air - no health hazard, maybe a pressure risk. Acetylene - do you really need this gas - this is particularly dangerous
A leak from more than 1 pipeline at a time is probably unlikely. Ensure your gas regulators/isolation valves are identified/labelled. Can easily be shut off. Gas detection should be onsidered. Ensure the lab is sufficiently ventilatied. The British Compressed Gas Association Guidance Note 11 gives good advice, as well as formula for calculating flammable atmopsheres and oxygen enrichment %s.
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 1 user thanked Ian Bell2 for this useful post.
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Rank: New forum user
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Thanks for the pointer on the guidance document, it's been really useful Ian Bell2 . We do need to run an acetylene rich flame for our atomic absorption spectrmeter so substitution or elimination is not an option.
The argon/methane is a 90%/10% mix so does require some consideration for the methane content. I am being asked to consider the use of gas monitoring equipment for the areas we use propane, argon and argon/methane but I feel that the liklihood of leaks from either internal pipework or regulators within these areas is negligible and when weighed against the cost of the monitoring equipment I think it's not practicable. As the equipment, regulators and pipework are part of a regular inspection process and are sited in rooms with good ventilation do I really need to go down the route of installing monitors?
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Rank: Super forum user
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Legally, the applicable safety legislation is/are DSEAR - Dangerous Substances & Explosive Atmospheres Regs There are 2 general scenarios that are usualy covered - a short term gross leak - e.g. valve left open, a pipe left disconnected and gas escaping. A long term slow leak, while the room is unoccupied e.g. over night/weekends etc. Could a slow leak eventually lead to a falammable or asphxiant atmosphere? We have gas detectors in the labs where I do much of my work, to cover the slow leak scenario. For flammable atmosphere, you would most likely assess as a 'Secondary' leak resulting in a small Zone 2 around regulators or Zone 1 around gas connection points (i.e. snap connectors). Pipes should as far as possible be extruded/continuous/welded) as much as possible. Such pipes are not considered to be leak sources, so wouldn't require and hazardous area classification. BS60079-10-1 is the standard for hazardous area classification.
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Rank: Super forum user
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Gas cylinders themselves do not generally leak. The leak occurs in the pipework coming off the cylinder into what ever equipment you are using. This is down to someone not fitting the pipework correctly or using the wrong materials. The problem typically occurs just after it has been installed, which is where gas monitoring is useful. Once it has been installed all joints should be checked with an appropriate leak detecting solution- the pipework is rarely continuously welded in a lab setting. You might still have a small leak but if the room is well ventilated it should not be a problem and not form a hazardous or dangerous atmosphere. The small leak might be a problem if you are using something like carbon monoxide or sulphur dioxide which are of course toxic. When I see equipment that uses a carrier gas in a lab, I always ask the question where does the gas go after it has done its carrying: is vented through an extraction system or burned off using a pilot flame? Surprising how often people don’t know the answer to that and have to check up the manual.
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