CO2 detectors: health and safety back up for commercial kitchens by Steve McMahon, Managing Director of S&S Northern
From its inception in 2001, BS6173 in its original and subsequent formats has provoked discussions in the industry about whether overrides are acceptable when using ventilation and gas interlock panels. Indeed, for a number of years the industry allowed overrides to be fitted to interlock panels. Arguments both for and against overrides have a certain degree of reasoning behind them. On the one hand it has been argued that if a gas engineer went to site on the report that the gas supply had failed and found the air pressure differential switch was faulty, the engineer would be able to override the pressure differential switch until a replacement could be fitted, assuming a risk assessment had been carried out and the fans were operating correctly. This would obviously allow for the smooth running of the kitchen whilst the repairs were taking place. On the other hand it was argued that a restaurant owner or chef could easily override an interlock panel if the fans were not operational and create a hazardous or harmful environment for staff. Both of these arguments have merit, but Technical Bulletin 140 (TB140) introduced in April 2012 has now provided some clarity to these discussions and brought valuable guidance to installers.
Everyone in the industry agrees that good ventilation is essential in commercial kitchens and this should always be the case going forward. An effective way to determine if a kitchen’s ventilation system is working correctly is by measuring the Carbon Dioxide (CO2) levels in the working area. The newly introduced TB140 now offers a means of keeping the kitchen running if the fans or air pressure differential switches fail through a secondary or back-up system. Essentially the gas interlock system should function as specified in BS6173:2009 and a backup system in the form of Carbon Dioxide detectors can be used in the event of fan failure. The gas interlock system monitors the operation of the fans and shuts down if the fans fail; the Carbon Dioxide detectors can then be used to monitor the quality of the air in the kitchen.
Carbon Dioxide detectors work at two levels, 2800ppm and 5000ppm. At Level 1 (2800ppm) the head of the kitchen either needs to increase ventilation by opening doors or windows or reduce the cooking load. If insufficient ventilation is available the Co2 levels will continue to increase and at Level 2 or 5000ppm the gas will be shut off.
The location of Carbon Dioxide detectors in the kitchen is very important and TB140 states the detectors should be mounted at not more than 2.5m from the floor and centre of the working area. TB140 goes on to state that “it may be necessary to install more than one detector to ensure representative conditions are monitored.” It is also recommended by TB140 that the Co2 monitoring back-up intervention should be limited to no more than 24 hours.
BS6173:2009 states that manual overrides are no longer acceptable on new installations. However there are still many products in use within in the industry that have overrides fitted. Before TB140 was published it was recommended that a risk assessment should be carried out on interlock systems with manual overrides. It was agreed that if the override did not pose a risk, the panel could continue to be used and a “Not to Current standard” (NCS) was issued to the owners of the kitchen. The use of Carbon Dioxide detectors as a secondary system where manual overrides are fitted is now an option to assist in this situation, although kitchens should still be marked as NCS as required by BS6173:2009.
S&S Northern manufacturers and supplies CO2 detectors for commercial kitchens across the UK. The company supplies Councils, contractors and end users with Carbon Dioxide detectors for their commercial kitchens. These can act as secondary back-up systems to interlock panels that are already installed or can be fitted with interlock panels on new applications, they allow the safe and smooth running of the kitchens in the event of the pressure differential switches failing or any interruption to the operation of the fans.
Biography: Steve McMahon, Managing Director of S&S Northern
Steve McMahon has worked in the heating and ventilation industry for over 38 years.
He started his career at Woods of Colchester as a trainee estimator and was promoted to various roles including external sales engineer. In 2001 Steve established S&S Northern, supplying gas safety systems for commercial and industrial applications.
After a few years of trading, and with the business expanding, Steve brought in family members to join the business, in particular his and fellow director Sue’s sons, to bring new ideas and plan for the long term future of the company.
S&S Northern now employs 12 staff in Lancashire and Essex.
For more information about S&S Northern’s CO2 detectors and S&S Northern’s full range of products, including gas interlock systems, please visit www.snsnorthern.com, email email@example.com or call 01257 470983