what is different betwen Process zero and atm zero?

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what is different betwen Process zero and atm zero?..

Atmospheric zero is when you check the zero of your
transmitter with HP and LP sides of your Tx open to atmosphere.
Process zero is when you check the zero of your transmitter
with the actual process pressure, where this transmitter
will be used, applied to the HP and LP side of your
transmitter. In both cases the transmitter should read zero.
So if you will be using this Tx on a vessel with a 100Bar
process pressure you need to apply 100bar on both sides
simultaneously and make sure it still reads zero, before you
start your calibration.
With such a high pressure there will definitely be a zero
shift so you need to compensate for it during the
calibration. The lower the process pressure the smaller this
zero shift will be. If your process pressure is below 5 Bar
you do not have to concern yourself about doing a process
zero check since the zero shift is so small you may use it
as is and just do the atmospheric zero check.
If you are not sure how to do this let me know.
Good luck

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