Abstract: A fire detection system includes an elongated liquid filled tube with a fluid coupled alarm switch, with a flexible diaphragm which senses a change from the liquid to vapor phase in the presence of an overheat or fire condition to provide an alarm. To prevent false alarms due to normal expansion of the liquid under changing ambient temperature conditions, a compensator is provided which in one form is a pair of mechanically coupled bellow type containers, filled with the same liquid which will expand at the same rate as the fluid under normal ambient temperature conditions but in a fire condition will resist faster expansion thus causing the alarm switch to be actuated. In another embodiment, a bimetallic bellows is utilized to match the liquid expansion but resist greater vapor pressure. Yet in another embodiment the change in liquid flow rate due to a fire condition is sensed to prevent further accommodation to the normal increase in volume of the liquid.

Abstract: A pressurized extinguishant release device with a rolling diaphragm includes a closed elongated sensor tube filled for example with 50% water and 50% ethylene glycol which terminates in an enclosure sealed by a circular head portion of the rolling diaphragm. On the other side of the head portion is a piston connected to a penetrator retained against the diaphragm by a shear pin. The penetrator is positioned above a brittle membrane which encloses a pressurized extinguishant. Heating of the liquid filled sensor tube to a certain temperature will cause a vapor pressure to push against the diaphragm head to cause the shear pin to fail propelling the penetrator into the membrane and thus allow the extinguishant to flow.