BS6173:2009 was introduced in 2009 and relates to commercial kitchens. It states gas should not be available if the ventilation fans are not operating. Proving of the fans can be done either by air pressure differential switches or a current monitor. If either at start-up, or during the course of the day, the fans fail or are turned off the gas valve should close.
Another aspect of BS6173:2009 is gas pressure proving. The standard states if any of the catering equipment does not have a flame failure device a gas pressure proving system should be installed. At start-up the panel is to check the gas line to ensure no appliances are in the “on” position. This is to ensure gas cannot escape into an area that could possibly be unsupervised.
BS6173:2009 relates to commercial kitchens which are either new or which are having a major Refurbishment. In the eyes of GAS SAFE a major refurbishment is when a kitchen either has a new fan or canopy fitted, or if additional or larger appliances are fitted. For instance if a four ring burner is replaced with another four ring burner GAS SAFE do not consider this to be a major refurbishment and therefore it does not have to comply with BS6173:2009. However the people who are operating the kitchen must be informed the kitchen is NCS (not up to current standard) and that it should be brought up to standard if a major refurbishment takes place in the future.
“Appliances shall be interlocked with any mechanical ventilation system that is fitted to enable their safe operation.”
“An interlock shall be provided which will cut off the gas supply or prevent the operation of appliances if the mechanical ventilation system provides an inadequate airflow rate for the safe operation of appliances and the safety of personnel.”
“An interlock on a new installation shall not be fitted with an override function.”
“Only detectors designed to operate in a commercial catering environment shall be installed. They shall give an audible alarm and be linked with an automatic gas shut‑off system which is fail-safe and requires manual intervention to restore the gas supply.”
Technical Bulletin 140 (Edition 2)
TB140 (Edition 2) has now been withdrawn and has been replaced by IGEM/UP/19 which was published at the beginning of November 2014.
TB140 was originally introduced in April 2012 and was designed to help kitchen staff, restaurant owners and commercial catering engineers and in the event where a CO2 Monitor was fitted and the air quality in the commercial kitchen was at a safe level (below 5000ppm) they could have had access to the gas supply for up to 24 hours in the event of a fan failure. However, in June 2014 TB140 (Edition 2) was released to supersede Edition 1.
Technical Bulletin 140 (Edition 2) discusses the interlock requirements for new installations. When dealing with a Type A appliance CO2 Monitor can be used alone. However, when dealing with Type B appliances where mechanical ventilation has been installed a current monitor or air pressure differential switch is required to check the ventilation is operating before allow the gas solenoid valve to open. A CO2 Monitor can be used in conjunction with the primary interlock, but they are not acceptable as the only means of interlock.
With regards to the CO2 Monitors, Technical Bulletin 140 (Edition 2) explains that CO2 Monitors should be mounted no higher than 2.5m above floor level, dependant on the layout kitchen it may be necessary to install more than one CO2 Monitor to ensure conditions are monitored accurately. The CO2 Monitor should alarm at first and second stage, the first stage warning staff at 2800ppm to notify staff that they should increase ventilation. The CO2 Monitor should also alarm at 5000ppm and shut the gas solenoid valve as a safe environment has been maintained.
“CO2 monitoring may also be used in conjunction with fan flow/pressure switches or power monitoring for Type B appliances, but they are not acceptable as the only interlock for Type B appliances.”
“Levels of 2800 and 5000ppm are now proposed for first stage and second stage alarm and shutdown conditions respectively.”
“For Type B appliances this shall be as a minimum either a fan flow/pressure switch or power monitoring interlock.”
IGEM/UP/19 was introduced in November 2014 and supersedes TB140 (Edition 2) released in June 2014.
IGEM/UP/19 relates to commercial kitchens. It states gas should not be available if the mechanical ventilation is not in operation. Proving of the fans can be done either by air pressure differential switches or a current monitor. If either at start-up, or during the course of the day, the fans fail or are turned off the gas valve should close.
IGEM/UP/19 discusses the interlock requirements for new installations. When dealing with a Type A appliance CO2 Monitor can be used alone however an interlock may be included. However, when dealing with Type B appliances where mechanical ventilation has been installed a current monitor or air pressure differential switch is required to check the ventilation is operating before allow the gas solenoid valve to open. A CO2 Monitor can be used in conjunction with the primary interlock, but cannot be used as the only means of interlock. No temporary bypass should be fitted which allows the gas solenoid valve to open in the event where the mechanical ventilation is not in operation.
The CO2 Monitor should alarm at first and second stage, the first stage warning staff at 2800ppm to notify staff that they should increase ventilation. The CO2 Monitor should also alarm at 5000ppm and shut the gas solenoid valve as a safe environment has been maintained.
“In accordance with BS6173 over-rides to interlocks and interlock systems are not permitted and, as appropriate the responsible person shall be advised accordingly including within any written report.”
“In addition to the markings required by BS EN 60730-1, the control system to be indelibly marked with the substance of the following: “WARNING: This is a safety control – Do not tamper””
“Actuation of an alarm when the CO2 level is above 2800ppm shall cause a visual or audible warning to occur. If the CO2 level rises above 5000ppm, any interlock shall cause lockout of the gas system to occur”
“CO2 Monitoring alone is not acceptable as the main interlock for Type B appliances but may be used in conjunction with air flow, air pressure or fan power monitoring”
UP11 was written in order to clarify gas safety in educational establishments such as schools, colleges and university explaining in details requirements in standard science laboratories and home economics rooms.
IGEM/UP/11 shows that it is mandatory is science laboratories to have the ability to isolate the gas supply, whether this be by means of a manual valve (ECV) such as a quarter-turn, or an automatic isolation valve (gas solenoid valve). However in section 6.2.4 it does say where a gas solenoid valve is installed the system must include a “downstream integrity check” otherwise known as a gas proving test. This gas proving test will check all the downstream gas pipework for any leaks or open appliances. If the gas solenoid valve is ever caused to close, in the event of a shutdown, it requires manually resetting by means of a key switch or key code.
IGEM/UP/11 goes on to discuss the requirements for CO2 and ventilation in a home economics room to ensure the safety of the children and to ensure air quality is at a safe level. For a new installation, where ventilation is installed to ensure gas safety then this should be interlocked by means of air pressure differential switch, current monitors or carbon dioxide monitoring. Where CO2 monitors are used in order to interlock with the ventilation, the carbon dioxide monitor should alarm at 2800ppm to signify a dangerous level of CO2 in the air and should isolate the gas supply if the parts per million ever exceed 5000ppm.
“Where an AIV is required the system shall include a downstream integrity check before can be re-opened.”
“Such automatic means of isolation shall, in the event of a shutdown, require manual re-setting to take place such that check is preformed to prove that all the downstream gas isolation valves are closed.”
“When measured a seating height, during the continuous period between the start and finish of a teaching day, the average concentration should not exceed 1500ppm.”
“High levels of CO2 shall cause an alarm at 2800ppm and shut down of gas supply at 5000ppm.”
Building Bulletin 100
Building Bulletin 100 is designed for fire safety in schools and explains fire safety requirements for science laboratories, kitchens and school boiler rooms. With regards to science laboratory which have a gas supply, these should all be fitted with a lockable isolating valve to ensure gas taps and appliances are closed at the end of the day.
All home economics rooms which have gas cookers installed in should also are fitted with lockable isolating valve to enable gas supplies to cookers to close at the end of the day. With regards to the boiler rooms in schools, and fire safety is a requirement for existing boiler rooms which have been upgraded or refurbished. An emergency knock-off button should be installed at the entrance of the boiler room and connected up to the isolation valve so when this is pressed in emergency the gas supply will be shut-off. Heat detectors are mandatory above each boiler, however smoke alarms should not be used as these may cause nuisance tripping and cause a number of false alarms. Auto-reset is allowed on power failure to prevent the risk of frozen pipes, however in the event of an alarm the system must be manually reset to restore the gas supply. Where a gas detection system is installed, in the event of an alarm the system should give an audible alarm and isolate the gas supply.
“A means of automatically shutting off the fuel supply in the event of a fire. This should include an emergency shut-off push-button at the entrance to the boiler room.”
“In the event of a genuine alarm, the system should require manual resetting, but if it is purely a power failure and appropriate self-proving devices are in place, then automatic resetting is appropriate to prevent the risk of pipe freezing during weekends or holiday periods.”
“Heat detection is preferable to smoke detection in a boiler room as smoke detection is more likely to cause false alarms.”
“In addition, a carbon monoxide or carbon dioxide detection system is often required in boiler/plant rooms for all fuel types, particularly where a boiler/plant room forms part of the school building