MINUTE DIFFERENTIAL PRESSURE DETECTOR

PURPOSE:To reduce film rigidity errors, by arranging one magnet to turn with respect to a lead switch as opposed thereto in response to a diaphragm to enable a stable ON-OFF detection operation. CONSTITUTION:As a differential pressure generate between a high pressure side pressure chamber 1 and a low pressure side pressure chamber 2 respectively communicating with a high pressure input end 11 and a low pessure input end 12, a faceplate 32 of a detection film 3 and the portion of a diaphragm membrane 33 react. Then, a projection part 36 makes a rotating member 4 turn clockwise against the energized force of a spring 8 so that an electromag net 5 will be rotated by a moment force with a projection 42. A lead switch 7 set facing the magnet 5 performs a switching depending on the effect of variations in the magnetic flux thereon. Thus, the adjustment of the stroke of the detection film is made possible by regulating the distance between the pivoting point of the magnet and the action point of the rotating member there by permitting a reduced effect of film rigidity while doing the detection of minute differential pressure at a high repetition accuracy and even down to the low pressure range.