The lfas employs a differential pressure to actuate a precision snap switch at chosen pressure setting. This may be the difference between atmospheric and a negative or positive pressure or between any two given pressures. When a change of pressure occurs between the negative pressure chamber and the positive pressure chamber the main diaphragm activates the snap switch at a pre-determined value. the lfas pressure cut-off switch is manufactured from selected compound derivatives of polycarbonate & pbt offering exceptional thermal and dimensional stability at elevated temperatures up to 105℃ when used in contaminated atmospheres of air, products of combustion, l. P. Or natural gas. It has been designed to meet the low pressure, high temperature specifications of future generations of fanned gas and similar appliances where differential pressures form part of an integral control systems.