差压压力计检测两个压力之间的差异。测量元件，例如波登管，连接到两个腔室，每个腔室包含要比较的两种介质之一。如果两个腔室中的压力相等，压力计将不显示信号。只有当两个压力彼此不同时，测量元件才会移动，指针也会随之移动，显示压力差的绝对值。

　　原文：

　　A differential pressure manometer detects the difference between two pressures. The measuring element, e.g. a Bourdon tube, is connected to two chambers, each of which contains one of the two media to be compared. If the pressures in both chambers are equal, the manometer will show no signal. Only if the two pressures differ from each other will the measuring element move, and with it the pointer showing the absolute value of the pressure difference.