Abstract:
The function of the manometer is to enable small pressure differences to be measured at a distance. The instrument will measure either the difference of two pressures or a single pressure relative to atmosphere. The accurate measurement of small pressures at a distance remote from the source is not very satisfactory by the orthodox methods using long lengths of tubing. The chief difficulty is that due to lag. This problem became apparent when exploring the wind velocity and direction on the Whirling Arm at the National Physical Laboratory. From the yawmeter to the Chattock gauge, which one normally uses for pressure measurements, the length of tubing required for each lead is of the order of 120 ft. This means that a considerable time must elapse before a reliable reading can be obtained, particularly if the pressure difference is very small. The sensitivity of the manometer described is comparable with that of a 26 in. Chattock gauge and is capable of measuring pressures up to about 3 in. of water.
