Hi,

I was just wondering if anybody knows where I can find specific Information/Guidance on how to test a confined space for toxic gases etc.

I am aware of top, middle, bottom. But what I would like to see is a approved technique/recommendations.

I have had a looked at the ACOP for confined space entry and it does have some information but it is very generalized and does not go into the specifics of how different spaces should be tested.

I know some will say Risk assess each space and I understand that but what I am looking for is technical information/reference material that can be used to add to the assessment.?

Thanks

Agree with your top / middle / bottom.

However, if you have a suspicion as to what may be in the space check the density of the potential gas and concentrate in the relevant area. If heavier than air, ensure that corners and areas where gas can pool are specifically checked.

Evening Ian,

We are in the ship repair industry and tank entry is every day business. We have independent competent lab technicians who have to undergo 6 months training to achieve UKAS accreditation. Our regime insists on 24hr venting prior to testing to bring the tank to an acceptable level for entry under control by the lab tech.
The upper / mid / lower / nooks crannies and all analysis is performed appropriate to the previous contents ie sewage, fuel, ballast, sullage etc. If it fails they will decree continuous venting appropriate to the size, volume and shape before a retest can be performed. Once satisfied, the tank can be cleared for entry.
It does not stop there......a tank can be subject to many processes during its repair cycle, survey, cleaning, blasting, weld repair, painting. Intentional inert gas introduction needs to be calculated so that the correct volumetric flow rates for continuous vent can be determined (both forced & scavenge) to maintain the RAQ. Then there is the painting governed under DSEAR for explosive conditions, again to calculate the rate of spray which in turn allows you to work out how much vent is needed to maintain 10% LEL. There are a 1001 scenarios with CS entry, the crux is in the assessment to determine how your schedule of works will be conducted with science thrown in.
I would agree with Ray and hire in an accredited competent person, because when tank work goes wrong it can often go horribly wrong.
I hope this is of help.
Best regards
Alex