Trial Constraction of Manometer for Small Pressure Difference and Measurement of Liquid Friction Coefficient on Low Re Numbers

In order to measure the pressure drop between near two point in a duct flowing gas with low velocity manometer for very small pressure difference was made on a trial basis. Mechanism of trial equipment are as follows. Two inverted bells are suspended on the free end of two cunti levers respectively, strain gauges are put on the up and under side of near the each fixed end, these gauges are bridged as differential connection and in order to prevent the effect of surface tension a surface active agent was added to sealing water. Output of bridge was input to the DC amplifier and diference of pressure aplyed in both bells are indicated on DC curent meter directly. Pressure drop between two point distance of 750mm on the 20.3mm ID vinyl chroride pipe flowing air was measured with the trial equipment. Liquid friction coefficient was obtained by revers calculation from measured data. Obtaind values of coefficient agreed with theoretical values with-in error of about 10% in the region of 40&acd