What you need to know about Technical Bulletin 140

Updated guidance on gas ventilation and extract requirements has led to some confusion in the market, particularly around the issue of air quality and carbon dioxide levels. Engineers need to be mindful of how they interpret the guidelines, writes Peter Kay, CEDA’s director of technical support.

"The introduction of the Gas Safe Register Technical Bulletin 140 was intended to clarify certain information relating to effective ventilation in kitchens that had previously been published by the Health and Safety Executive in the Catering Information Sheet 23 (rev1).

The document was prepared by the Institution of Gas Engineers and Managers and published by Gas Safe Register in May 2012, with one major topic addressing air quality and measuring levels of carbon dioxide.

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Whilst the document has corrected one mistake in transferring the information from HSE CAIS 23(1), it has lead to confusion for a number of reasons.

Firstly, the bulletin not only contains guidance for engineers on what they are obliged to do under the regulations, but it also contains a lot of other information which might be useful to a designer, but which could be misinterpreted by an overzealous engineer as being a requirement of the regulations.

The two types of information are mixed together and therefore easy to confuse. During the drafting and consultation stage, the CEDA Technical Steering Group suggested that the bulletin should be edited into two sections: One relating to ‘Guidance for engineers working in commercial kitchens’ and the other providing ‘Useful information for designers of ventilation systems for kitchens using gas fired equipment’.

We even edited the draft bulletin to this format, however the recommendation was not taken up when the bulletin was published. One example of confusing information relates to interlocks. It has been a requirement for several years that there should be an interlock between the extraction fan and the gas supply to ensure that gas catering equipment cannot be operated without the mechanical extraction being operational.

When this regulation was introduced some manufacturers of interlock systems considered that it was beneficial to provide an override on the system, which would allow a responsible person to continue to use the cooking equipment even if the extraction had failed.

It was intended that the responsible person would carry out a risk assessment and take remedial action such as opening windows and doors and to turn off some items of cooking equipment to reduce the build up of CO2 until the fault in the extraction system had been rectified.

It was, of course, possible that the override would just be left operational, thus putting staff at risk from CO2 poisoning, and therefore CAIS23(1) made it clear that overrides were not acceptable. Technical Bulletin 140 repeats the above information but introduces the “concept of a secondary CO2 controlling interlock that could be actuated upon a failure condition”.

Whilst this is a sensible, if somewhat costly additional safety idea, it is certainly not a mandatory requirement, but an overzealous engineer could interpret it differently. Indeed one distributor has already interpreted it to mean that they have to install CO2 monitors in addition to the normal interlock.

Secondly, different regulations apply to commercial and domestic premises and the bulletin is ambiguous in defining commercial premises. Rather than giving clear guidance, it leaves it to the individual engineer to carry out a risk assessment to determine what standard to apply.

The bulletin indicates that such installations as in B&B premises normally would be considered to fall under standards relating to domestic dwellings. However, it states “some installations may border on commercial activities due to their high cooking loads”.

It is the opinion of the CEDA Technical Steering Group that engineers should be given clear guidance on the basis that any establishment using gas fired commercial catering equipment other than for purely domestic purposes should be considered as commercial.

Thirdly, the bulletin explains what an engineer has to do in terms of measuring, however it does not stipulate when this should be done. The British Standard (BS6173 2009) relating to commercial catering installations indicates that it is not necessary to carry out a full air quality test every time an engineer works in a kitchen.

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The following is a summary of recommendations that CEDA has issued to its members based on best practice and clause 14 of the standard.

– When working on gas equipment in any kitchen for the very first time.
– When carrying out routine maintenance of gas equipment.
– After installing any additional or replacement gas fired item.

In any kitchen where it is suspected that the extraction/make up air system may not be working satisfactorily i.e. very hot working environment, high levels of condensation, catering staff complaining of working environment.

Finally, the bulletin introduces a second ceiling for CO2 levels of 5000ppm whereas CAIS 23(1) stipulated that anything over 2800ppm was considered a problem. Prior to the publishing of TB140, if an engineer found that the CO2 level was above 2800ppm he would advise the person responsible for the installation to open windows and doors and shut down appliances until the level has settled below 2800ppm.

If this was achieved, the installation would be considered ‘At Risk’ under the Gas Industry Unsafe Situations Procedure and the person responsible would have to sign to say that they took responsibility.

If it was not possible to reduce the CO2 levels below 2800ppm, then the installation would be considered ‘Immediately Dangerous’ under GIUSP and the engineer would have to turn off the supply and report the installation. This was a common sense approach which erred on the side of safety.

The wording of TB140 is similar to that in CAIS 23(1), however the flow chart which is appendix 1 now introduces a second ceiling of 5000ppm at which an installation automatically becomes ‘Immediately Dangerous’.

This suggests that anything between 2800 and 5000ppm cannot be ‘Immediately Dangerous’ and is therefore ‘At Risk’. This could be interpreted by a caterer as OK to carry on using once the engineer has left the premises. The CEDA Technical Steering Group considers this to be misleading and could lead to unsafe situations.

CEDA and colleagues from CESA have registered their concern about the bulletin with Gas Safe Register and asked for it to be withdrawn until a clearer document can be published. Gas Safe Register has stated that they cannot just withdraw the bulletin, but they have agreed to convene a meeting to hear the concerns and hopefully act upon them."

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