I am working with SGT 700.

I came across a peculiar thing wkile looking at the HMI.

The Dp across filter set is 0.55kPa, further the Dp across the Compressor inlet plenum (used to calculate air mass flow) is 9.3kPa and finally at compressor inlet the ABSOLUTE Pressure is 95kPa.

Calculating the Atmospheric Pressure = 95 + 9.3 + 0.55 = 104.85 kPa! Which is not phsically possible as atmospheric pressure can be a max 101.3kPa.

Am I missing out on something?

 

Don't know where you are located but the atmospheric pressure where I'm at is 30.18 inch of Mercury = 102.2 kPa which is above your "max 101.3kPa". 104.85 kPa = 30.96 inch of mercury would be a high pressure for my location, but the highest ever recorded atmospheric pressure according to weatherstem.com was " The highest sea-level air pressure ever recorded was 1083.8 mb (32.01 in. Hg) in Agata, Siberia on December 31, 1968; produced by a very cold, dense air mass.". That's 108.38 kPa.

 

The zero of an absolute pressure transmitter might have drifted over time.

 

101.3 kPa is "standard pressure" when correcting volumetric measurements to "standard conditions" in the measurement world. The pressure at any point on the earth is a function of the weight of the air mass above the location which changes with temperature, humidity and altitude.