Pressure Switch
A device that monitors a pressure (gas, air or water) and opens or closes a control circuit when it crosses a set threshold, one link in a gas appliance's safety chain.
What is a pressure switch?
A pressure switch is a pressure-operated switch. It compares the pressure of a fluid — fuel gas, air or water — to a set threshold, then opens or closes an electrical contact when that threshold is crossed. On a gas appliance, this signal is used by the control system to enable or interrupt operation.
What types of pressure switches are found on a burner?
On a commercial gas burner, gas pressure switches (low and high) and air pressure switches are common. The former protect against a fuel supply outside its range; the latter confirm that the air needed for combustion or flue gas venting is established before ignition.
Why is it a safety device?
A pressure switch detects an abnormal pressure condition before it becomes a hazard. On a steam boiler as on a hot water generator, checking and setting it is part of the verifications during commissioning and maintenance carried out by a qualified technician, in line with the manufacturer’s instructions and applicable requirements.