The major issue that this document attempts to give resolution to is:

What happens when a fan fails that forms part of the ventilation design for a commercial kitchen?
It is still the case that the CO₂ level within the staff working areas of the kitchen should be below 2,800 ppm and that the gas should be isolated should the CO₂ level rise above this limit. Above this level but below 5,000 ppm the kitchen will be designated at risk by a Gas Safe technician. However, where an interlock proving system is fitted with CO₂ monitoring should a fan failure occur a competent person can activate the CO₂secondary interlock system. This will allow the kitchen to be used for up to 24 hours so allowing time for the ventilation to be restored. The CO₂ level higher limit is increased to 5,000 ppm during the 24 hour period. Should the CO₂ level rise above that level then the gas must be isolated. Secondary interlock must form part of a primary interlock system. It is not acceptable to have a separate system.

Facts about CO₂ monitoring in a commercial kitchen.
Only use CO₂ detectors that have a PTFE filter that can be easily changed periodically. Although commercial and industrial CO₂ detector heads will make some allowance for unclean air they could eventually become blind in the air of a commercial kitchen.

Bearing in mind that interlock overrides are not allowed, it could be too easy to use a CO₂ secondary interlock as an override by just switching the fans off and activating the secondary interlock function. Cold make-up air and noise used to be reasons why overrides were used by kitchen staff.

It is obviously important that the interlocking panel used has been designed so that what is described above cannot happen.

Also, it is important that a primary interlock fitted with CO₂ has the ability to change from 2,800 ppm to 5,000 ppm should the secondary interlock function be activated.
See also British Standard 6173/2009 and IGEM/UP2, Edition Two

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One of the main changes that this standard has implemented is the removal of secondary interlocking. Over-rides, fan bypasses or secondary interlocking of any form are not allowed and the design of any fitted interlock system should be so that an override is not included.

It is important that the interlock and ventilation scheme has been designed to ensure adequate ventilation levels are met and that Gas Safety (Installation and Use) Regulations 1998 (GSIUR) are being followed.

This statutory document states:
“Regulation 27(4) No person shall install a power-operated flue system for a gas appliance unless it safely prevents the operation of the appliance if the draught fails.”
As a mandatory document, this takes precedent over UP19.

UP19 also provides further support for the monitoring of CO₂ levels to determine adequate ventilation levels are met and the potential for controlling the mechanical ventilation above the set minimum.

For newly designed kitchens the CO₂ level within the staff working areas of the kitchen should be below 2,800 ppm and that the gas should be isolated if the CO₂ level rises above this limit. For existing installations where a 5,000 ppm limit is reached the kitchen gas supply will be isolated until the CO₂ reduces.

Only CO₂ detectors that have been designed for the arduous conditions of a commercial kitchen should be used, with features such as a PTFE filter that can be easily changed periodically being considered. Although commercial and industrial CO₂ detector heads will make some allowance for unclean air they could eventually become blind in the air of a commercial kitchen.

Please don’t hesitate to contact us to discuss the location and mounting of CO₂ detectors in a commercial kitchen. See also these two other standards British Standard 6173/2009 and IGEM/UP2, Edition 2, which will help you.

If you require any additional information on our systems to help meet these design standards or wish to discuss the standards further please don’t hesitate to contact us.

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Section 2:
Scope 2.4 states that the document procedures apply in relation to the following (amongst others areas):
“Where there has been a complete loss of pressure for any reason, note, The closure of a valve, for example, the ECV, can result in the complete loss of pressure which necessitates tightness testing and purging before resumption of supply”

An explanation of the above in relation to gas pressure proving. The first referring to the words “can result in the complete loss of pressure”. When a solenoid or other type of ECV closes for whatever reason if a downstream boiler, appliance or Bunsen burner is switched on then the gas pressure will be lost.

This is likely to happen particularly where flame safety devices are fitted.

Further reasons for the use of gas pressure proving systems can be found in this standard IGEM/UP2, Edition 2.

If you require any additional information on our systems to help meet these design standards or wish to discuss the standards further please don’t hesitate to contact us.

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