These instruments are used where pressures are to be measured independent of the natural fluctuations in atmospheric pressure. As a general rule all the known types of element and measuring principles can be applied. The pressure of the media to be measured is compared against a reference pressure which, at the same time, is absolute zero.
For this purpose an absolute vacuum is given as reference pressure in a reference chamber on the side of the measuring element not subject to pressure. This function is achieved by sealing off the appropriate measuring chamber or surrounding case.
Measuring element movement transmission and pressure indication follow in the same way as with the already described over pressure gauges.
Pressure ranges are between 0 ~ 16 mbar and 0 ~ 25 bar in the accuracy class 0.6 to 2.5.
Credits : Asyiddin
