Vacuum system pressure issues
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Currently, the gauge pressure of the vacuum system shows -90 KPa; the pressure transmitter reads 100% when it is zeroed； The local atmospheric pressure is 95 KPa. Is the absolute pressure for those of you at sea currently 5 KPa? Still 10Kpa?
The pressure gauge shows it starts at 100%
This 100% is related to the range; don’t pay attention to it – just look at the atmospheric pressure and negative pressure gauges
Your transmitter should be a standard pressure transmitter, that is, it uses the local atmospheric pressure as a reference. The range should be such that 0% corresponds to -95 KPA, and 100% corresponds to 0 KPA. When there is no pressure and the device is in an atmospheric environment, the pressures on both sides are equal, resulting in a reading of 0 KPA; at this point, of course, the full scale is displayed. The reading will only drop when the system pressure is below atmospheric pressure after it is put into use. Absolute pressure is relative to vacuum, while gauge pressure is relative to atmospheric pressure
If the gauge pressure shows 10%, what should the absolute pressure be? Is it 10*95/100? Still 10? Still 5?
Does the table show 10%? How should absolute pressure be calculated?
It doesn’t matter if I missed some characters
Actually, the most accurate approach is to install an absolute pressure transmitter and use it as a reference. Use it to convert the gauge pressure.
If looking at the gauge pressure, it should be 5 kPa. However, during use, one should check the voltage transformer. For example, the Yokogawa eja310e that we commonly use costs several thousand yuan.