Frequently Asked Questions

What is a gas interlock / gas ventilation interlock?

A safety device to prevent the supply of gas to appliances if the mechanical ventilation is not operating correctly.

How does a gas interlock / gas ventilation interlock work?

A sensor monitors the fans to check that they are working correctly – it then allows gas to be supplied to appliances.

Why do we need a gas interlock / gas ventilation interlock?

All new commercial kitchens must comply with BS6173 (2009) and GSIUR27.
All commercial kitchens installed after 2001 must comply with BS6173.

What is current monitoring?

Current monitoring is a way of determining that the fans are working correctly.

What is gas pressure proving?

This is a means of proving that there are no leaks in the system and that no taps have been left open before gas is supplied to the catering area.

A gas pressure transducer is fitted into the pipework close to the appliance side of the gas solenoid valve. When starting the system the gas solenoid valve opens to fill the system and then closes. The system then checks the pressure from the sensor. If no leaks are found the solenoid valve opens to allow gas into the system.

Do I need gas proving / gas pressure proving?

You will need a gas proving system if any of your appliances do not have flame failure fitted. As it checks the whole of the installation, not just the burners, it is a good idea anyway.

What is a flame failure device?

A device fitted to a gas appliance burner that will turn off the gas to a burner if the flame goes out.

What is BS6173?

See British Standards at

What is DW172?

See our Catering Regulations page here 

What regulations apply to commercial kitchen ventilation?

Gas Safe bulletin 140
Catering sheet no 9
Catering sheet no 10
Catering sheet no 23

What is CO2 monitoring / carbon dioxide monitoring?

A CO2 sensor is fitted within the room. When a high level of CO2 is found, the controller can alarm to warn people to open windows and turn up the fans to increase the ventilation. If a CaterSense controller is fitted, the controller can increase the speed of the fans to ventilate the area. After a set time (eg 5 minutes), if the level is still too high, the gas solenoid valve will be shut off.

What is a demand system?

When the cooking load is increased, this normally has a direct effect on the heat produced and therefore requires increased ventilation. A demand system is a fully automatic system to control the speed of the fans to provide ventilation in accordance with the cooking load. This also means that energy is saved when only minimal ventilation is required.

What is a temperature based demand system?

A duct temperature sensor is fitted in the extract canopy of the kitchen ventilation system. When the cooking load increases, the temperature will increase and therefore the controller will speed up the fans.

What is a lab interlock / classroom interlock?

A lab interlock can isolate the gas supply, water supply and electricity supply by use of solenoid valves or in the case of electricity, a contactor, if any of the services are not required. The unit also performs the gas pressure proving function.

Can I control my heater battery / LPHW heater battery / electric heater battery from my interlock?

Some of our CaterSense range have the capability to control heater batteries. Please see heater battery control here.