Is n't the point of HAC zoning to identify where ATEX rated equipment is required. Otherwise whats the point of HAC zoning? If you are in a Zone 2 that the lowest level of risk, as you know.

Cat 3 equipment is acceptable in a Zone 2. Cat 3 is 'normal' protection

Cat 1, 2, 3 are to do with the fault tolerance / acceptability of faults within equipment while being used in a HAC zone. Cat 1 tolerates 2 faults, if I remember correctly, within equipment

I do have access to the full standards BSEN60079 series, but don't have time to look up a full answer.

How bad would it be, if you had a fire? Should guide your decision. Are we talking a tank farm with millions of liters of fuel to catch fire? A small workshop? etc

Thanks for the reply Ian, I already had that handout which is quite good, but unfortunately for me I need to delve a little deeper. I personally would be happy for Category 1 2 or 3 in the zone 2 as is allowed. However, I’m being put under pressure (not internal) to accept less than category 3.

If it helps any with pointing me at guidance, we are talking somewhere in the middle of your ranges say 20,000 L of LPG, and not so much a fire but explosion. There is very little chance of a leak in my view, but still possible. Zone two is normally accepted for there to be a persistence of a explosive atmosphere for less than 10 hours per year, but we are talking more like a one of incident. I will admit that the chances are exceptionally low.

However, I am still in a position of less than category 3 equipment which is highly likely to spark being in this zone 2. Hence my question MUST it be a minimum of category 3 or can you risk assess it away. Schedule 3 (1) states this may be possible, but I have read somewhere else that only for older equipment in use before 2003.

If I do risk assess away, what would be deemed acceptable reasoning. There is nothing in the ACOP or guidance ( or anywhere else) on this little caveat.

Chris

What is the job/task you are actually doing? You could consider erecting a temporary enclosure/tent over the work area - with a slight positive pressure. Thereby, given the low chance that a flammable cloud might be around, will not enter the enclosed area because its pressurised. Thereby creating a local non hazardous area.

Other than that, I refer to my earlier answer, in my view a min Cat 3 equipment is needed and the whole purpose of zoning is to identify where ATEX rated equipment is required. What you described, as you say is not ATEX/zone rated.

Surely Schedule 3 does allow you to put into place alternative risk assessment controls. However, if as you say, you can't implement alternative controls to give a temporary non hazardous area - then it remains a Zone 2 where ATEX rated equipment is required. Cat 3 equipment being the minimum requirement.

Other options to consider, as already suggested - full positive isolation of the plant, draining down/de-gassing the inventory in adjacent pipelines/equipment etc. Removal of the DSEAR dangerous substance.

I think you have just about self answered the question/problem you have for this task.

I don't think it gets any more in depth than that.

What standard/method has been used to determine the extent of the hazardous area?

It maybe the original classification was too pessimistic and resulted in too large a hazardous area.

The main standards for HAC are BS60079-10 or the Energy Institue document IP15.

If you re-assess your HAC zone extents, you might be able to risk away the problem you have my showing the extra control easures. Ultimately you can write a risk assessment that shows you have mitigated the risk.

How about rigging up some temporary ventilation fans to locally increase the air movement away from potential leak sources for the duration of the task? If the task only takes 10-15minutes, then that should be fairly easy to do?

Read your PM.

For those following my question

For a moment I thought I had it. From the HSE operational guidance document below: -

Dangerous Substances and Explosive Atmospheres Regulations 2002 SI 2002/2776

OC 284/7 Version 3

43  DSEAR Schedule 3 gives the criteria for the selection of equipment and protective systems. Para 1 of this Schedule recognises that there may be circumstances where the risk assessment made under reg.5 finds that the selection criteria are inappropriate or unnecessarily restrictive. In such cases, equipment of a lower category than that normally required for that zone may be used, subject to certain conditions, eg if workers can be excluded from the hazardous area and will not be at risk from any ignition of an explosive atmosphere.

44  If employers use the flexibility provided by Schedule 3, their decision must be fully justified in the risk assessment. Further guidance is given in the general DSEAR ACOP L138, paras 239-243.

Then in ACOP L138 paras 239-243 we have

 241 In areas where the ignition of dangerous substances could affect safety,

measures must be taken to avoid ignition sources occurring or being brought

into those areas. The measures employers should take include:

 (a) selecting and installing appropriate electrical and non-electrical

equipment that has been designed to be safe in hazardous areas. All

equipment for places where an explosive atmosphere may occur should

meet the essential safety requirements appropriate to the equipment

category as detailed in EPS;

Ahhhhhhhhhhhhhhhh

So is it just me, from the above where it suggests flexibility, there is actually none.

 Chris

From discussion so far, it seems locally increasing your ventilation appears to be the best option. With sufficient air movement for the duration of the job, should effectively remove the Zone 2 area or at least reduce it to Zone 2 NE (Zone 2 Neglible Extent) - Non hazardous.

Table D1 of BS60079-10 refers 'Good Ventilation' with a 'Secondary release' gives a Zone 2 NE Non hazardous result.

Thank you both for your posts.

Yes, we will have a permit type system in place for this operation, as we have quite a few hoops to jump through, including but not limited to segregation of non-essential personnel from the area. But two people will need to be there.

The difficulty is that it would not be a case of putting a couple of fans /blowers in the area as they would need to be intrinsically safe themselves or the electrics are outside the zoned area and lots of ducting. Still a potential option, though in my case it would remain classed a Zone 2 regardless (explanation too long to put in here).

For those of you who may be interested in this topic I have found further information in the ACOP specifically about my question (don’t know how I missed this when re reading the ACOP recently). However, this then brings another easier question ref para 381. Are (a), (b) and (c) “And’s” or “Or’s” ie must you have a and b and c, or is it any of them ie  a or b or c. I think it is the latter “or” but not certain. Any views

374 Where an employer intends to use the flexibility provided by the phrase in Schedule 3(1) ‘unless the risk assessment finds otherwise’, this decision must be adequately justified and recorded by their risk assessment which should confirm that the approach taken provides an equivalent level of safety to DSEAR. The derogation cannot be used to avoid the requirements placed on ‘responsible persons’ under EPS concerning the supply, importation and/ or putting into use of products.

381 The derogation referred to in paragraph 374 is intended to allow equipment of a higher or lower category than that normally required for the zone in question to be used where:  

(a) equipment is temporarily taken into a zoned area and alternative effective precautions are provided to control the risk. An example might be arrangements to isolate or shut down equipment to prevent the release of a dangerous substance;

(b) workers can be excluded from the hazardous area, and will not be at risk from any ignition of an explosive atmosphere;

(c) equipment of the required category is simply not available, but a lower category can be used in combination with other protective measures to achieve the purposes of these Regulations.

The more I read the more standards I come across, if you were to buy them all it would cost thousands (just for the standards before you actually put measures in place), surly that is not what H&S intended. But as it is, what it is, that is where a good consultant will quickly be worth their money.

Chris