Condenser Vaccum

If both instruments had a specified accuracy of +/- 1%, one read 1% high, the other 1% low - you would get a 20 degree difference. Look at the accuracy specifications for both instruments - I do not think you have a problem - unless you have a tripping setting of 910 mB!!

Hi,

can you elaborate further. Its true that we have +/-1% error accuracy specified.

But wont it give only +/-10mBar difference?

TQ

If both instruments have +/- 1% accuracy, then One could be reading -10mbar while the other +10mbar! and the difference could be 20mbar max.

But what about Calibration? Normally, you need to calibrate these instruments. The transmitter and the Gauge could be brought to read near the same values if re-calibrated. The issue is how much precise you need the measurement to be:+/- 1% means that the error could be 20mbar. If narrower error is required, then instrument with 0.5% should be used.

Under normal conditions the manometer is considered a primary instrument that requires no calibration. Therefore you should adjust your transmitter to trip at the pressure indicated on the manometer. That way both instruments will agree at the trip point.

If you are using a mercury column type of manometer, then it is more accurate and should be used as the reference. Electronic manometer, its range and linearity readings should be calibrated based on the mercury manometer readings. That is of course assuming the mercury and its glass tube encapsulations are clean, is considered as the gold standard in pressure measurements.

Make sure you are using the liquid specified by the manufacturer in the manometer. The other consideration for manometers is that they should be installed where the ambient temperature is within the range specified by the manufacturer also. If you hang a manometer close to an uninsulated steam pipe this will cause the fluid density to change and affect the reading also too hot will cause the fluid to evaporate. As far as calibration, for a manometer with both ends exposed to the same (atmospheric) pressure it should read zero.

Dear ,

You did not mention trip setting of transmitter.If your are talking about turbine condenser ,then you need a little worry.You need to describe some process detatil also.

Akram