Gauge, pressure, manometers diaphragms

DIN EN 837-3 1997-02 Pressure gauges - Part 3 Diaphragm Gauges and Capsule Manometers Dimensions, Measurement Method, Requirements and Testing. 

Sometimes diaphragm manometers for gauge pressure have an absolute pressure scale. Here one has to keep in mind that the measurement result is dependent on changes in atmospheric pressure. This effect can be partially compensated by rotating the scale or resetting the needle. For that purpose the instrument has to be evacuated down to a low pressure (lower than the lower limit of indication) and then to be adjusted to show zero. 

Vacuum gauge, capacitance manometer gauge A vacuum gauge that uses the deflection of a diaphragm, as measured by the changing capacitance (distance) between surfaces, as an indicator of the pressure differential across the diaphragm, the pressure on one side being a known value. 

Diaphragm pressure transmitters are most commonly used when an electrical signal is desired for data acquisition. These devices are also durable and reliable but require additional calibration and maintenance compared to a fluid manometer or spring gauge. 

Pressure can be measured by means of manometers which show the pressure in terms of the different levels of a liquid in a U-tube, by mechanical pressure gauges which record the differential effect of pressure forces on the inside and outside surfaces of a coiled tube or of a diaphragm, and electronic devices which measure the change of electrical characteristic of an element with pressure. 

Consider a correction to the pressure, P. If indeed the pressure we measure is due to molecular impacts with a surface in a manometer or a diaphragm in a pressure gauge, is that the actual pressure within the gas We are creeping up on a new concept that models a gas as a collection of small... 

Pressure exerted on a surface with respect to a reference - e.g. support of a colunm of liquid as in a mercury manometer deflection of a diaphragm as in a capacitance diaphragm gauge (CDG). 

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