Hi All,

I'm after some concrete advice after many, many different conflicting bits of info...

We have six hotels, all have internal cellars with CO2 for beer/post-mix lines, two hotels have an external diesel back-up generators that kicks in if the power fails for the comms systems. They are maintained - seviced and diesel refilled by external contractor. NO diesel is stored onsite, other than what is inside it.

Fire risk assessors and consultants say we need a DSEAR assessments on both diesels and cellars, local Scottish fire officer says we don't as we don't store diesel on site. Fire officer says we should ask HSE for advice, they just responded with generic email - don't give advice but here's our website info.

From what I can work out with the incredibly clear guidance, we do need it for CO2 as it's compressed gas, but unsure about diesel generators as we don't store it, doesn't mention equipment/machinery that uses it?

Thanks so much!!

In short - yes you do need a DSEAR assessment.

DSEAR applies to dangerous materials classed as flammable, highly flammable, oxidisers. Also for where there might be a risk of a pressurised spray mist leak from combustible fluids.

So in summary Co2 - no - this is not a flamamble gas.

Diesel - yes - although releatively low risk, diesel is still classed as a flammable liquid. Diesel has a flsh point of 55deg C. DSEAR applies for liquids up to flash points of 60deg C

DSEAR does not have a minimum limit below which DSEAR does not apply.

I spend much of my time doing DSEAR assessments. Send me a personal message if you want more information. There are ways to be cost effective about this, if your fire assessor won't do it for you.

The key question here is not whether DSEAR-based assessments are required, but whether the level of risk justifies a standalone DSEAR assessment conducted by a specialist.

Considering the two scenarios separately:

1. Diesel Storage and Generators

Diesel is classified as a dangerous substance under DSEAR, not because it is inherently flammable, but because if released under pressure through a small opening, it can form a fine mist that behaves like a flammable gas. This classification applied even before diesel was officially reclassified as a flammable liquid.

In the case of generators, there are typically two configurations:

• Separate Diesel Storage Tank & Generator – In this case, a DSEAR assessment is required.
• Combined Generator and Diesel Tank Unit – Here, the assessment depends on the tank size.
  • If the tank is integrated into a CE-marked unit, a separate DSEAR assessment may not be necessary for small tank sizes, as long as risks are managed through the unit’s design.
  • If the tank is larger or not covered by the generator CE marking, a dedicated DSEAR assessment is needed.

2. Liquid CO₂ (Carbon Dioxide)

Liquid CO₂ is covered under DSEAR, as pressurised gases can cause explosive-type events under fault conditions. The HSE specifically lists pressurised gases as dangerous substances.

It’s important to note that this risk is not a pressure explosion (covered under PSSR) but rather includes events like a BLEVE (Boiling Liquid Expanding Vapour Explosion).

However, the need for a formal DSEAR assessment depends on storage volume:

• Bulk Storage – Usually requires a specific DSEAR assessment.
• Cylinder Storage – Typically does not require a standalone assessment, as the risk is already managed under general safety measures.

Firstly, my opening sentence makes it clear that what follows is not a discussion on whether or not DSEAR applies or if DSEAR assessments are required. The focus is on whether it is proportionate to bring in a specialist for an expensive assessment on a simple system with minimal risk.

Secondly, the point I was making about diesel was that diesel has always been covered by DSEAR, even before it was classified as flammable. Its 'classification as flammable' is irrelevant to its status as a dangerous substance under DSEAR. While not relevant to diesel, as you know, any liquid can be classified as a dangerous substance if it is heated to or above its flashpoint, even if it is not considered a flammable liquid.

Thirdly, regarding your big red section, I did not state that DSEAR does not apply to small tanks. My argument was that conducting a standalone DSEAR assessment for a small generator with an integrated diesel tank that has been CE-marked as a combined unit would likely be disproportionate. The CE marking process should have already accounted for essential health and safety requirements, including the use of diesel as a fuel. I fully acknowledge that DSEAR applies, but a separate, specialist assessment may not always be necessary. With reagrds to a hotel, with a larger generator unit I would normally expect a full DSEAR assessment to be undertaken. 

Lastly, regarding CO2, I agree that in a hotel setting, a standalone DSEAR assessment is likely unnecessary and 'over the top'.. However, based on your response to the generator issue, you appear inconsistent. There, you appear to suggest that if DSEAR applies that a full assessment is always required. That approach does not align with a proportionate, risk-based methodology. To clarify, when I referred to bulk storage, I meant larger tanks or a significant number of cylinders, not just a few cylinders stored together.

The DSEAR concerns were correctly and appropriately identified within a fire risk assessment. The FRA assessor should have made an initial judgment on whether standalone DSEAR assessments were warranted. If they believe assessments should have been conducted but were not, this should be raised as a recommendation. Fire risk assessors must possess the appropriate training to make this initial determination. However, if there is any doubt, it is reasonable to recommend seeking further expert advice to clarify what, if any, additional assessments are required.

Hi Jemma

There have been some interesting theoretical debates on this thread.

I doubt that more than 10% of IOSH Members have ever heard of a BLEVE, let alone know that there are two broad classes of BLEVE, namely the Cold BLEVE and the Hot BLEVE.

Many sources of guidance including HSE say that you can reasonably decide that some risks are "NEGLIGIBLE" and then decide not to bother doing anything about them.

Seems to me that the prospect of a BLEVE involving CO2 storage at a hotel in the UK is "NEGLIGIBLE" unless you have bulk storage of CO2 and are either needing vastly more than is likely or are managing to lose a lot of the CO2 through e.g. leaking pipes. If you have leaking pipes get them fixed!! If only for financial reasons.

It also seems to me that a COMPETENT fire risk assessor should be capable of making the judgement that your CO2 system (in each hotel) is so small that any explosion risk related to CO2 in a hotel can be considered "NEGLIGIBLE" and that that COMPETENT risk assessor would NOT try and cover their back by recommending that you get a DSEAR assessment.

You are NOT (presumably) operating a "COMAH" major hazard site, nor e.g. a carbon capture facility. You shouldn't need to know about BLEVEs, except perhaps for some light research for your CPD record to prepare you for some future role.

...and I think that exactly the same type of thought process applies to your diesel generators, unless the generators were sited inside - which being the case they would need some careful consideration of e.g. a plant room - such that your fire risk assessor has not been prepared to say that they are sufficiently competent to discount that risk from needing a specific "DSEAR" asssessment as against an overall assesment of the risks.

Problem is that plenty of Toms, Dicks and Harrys are out there making money from doing Fire Risk Assessments (and many other things) when they are NOT competent to do what they are selling you - result is some upselling to say "You need to bring in an expert for this" as the assessor is not sufficiently competent to realise that they can discount some types of risk as being "NEGLIGIBLE". 

Might it be the case that the organisation that does your fire risk assessments also sells you water hygiene aka legionella assessments, management asbestos surveys and a few other things that come complete with templated reports?

Edited by user 04 April 2025 12:45:06(UTC)  | Reason: Typo