Measuring liq. density by differential pressure principle - using one sensor alternately connected to measurement and comparison containers

摘要

The pressure difference is measured between air bubble tubes in the samole liq. and in a comparison liq. It is applicable to the textile industry and results in considerably reduced measurement errors and disturbance sensitivity. Both pressures are measured by the same sensor (5). Its pressure-sensitive membrane is alternately exposed to the pressure in each air bubble tube (15,19) on the same side of the membrane and for defined periods of time. A control circuit (9) manages the connections between sensor and tubes ad places the output signals in the appropriate sample sections of the samole-and-hold circuits (10,11). The pressure difference is derived from a comparison of the sample and hold circuit contents at the end of the measurement oeriod.