Psia vs. Psig 1

[rebel]

Can someone please tell me the difference between gauge pressure and atmospheric? Psig vs. Psia. In laymen terms.

Thank you

 

[Rich2001]

psia is absolute pressure
psig is gage pressure

At sea level one feels 14.7 psia or 0 psig. A typical presure messuring device measures pressure compared to atmospheric pressure, hence psig.

 

[MikeMilburn]

Gauge pressure (psig)is the actual pressure above atmospheric, in other words if the gauge reads 30 psi there is actually 30 + 14.7 psi or 44.7 psi. Absolute (psia)is the total pressure on the gauge, or 44.7..Mike

 

[JKEngineer]

Just to underline what the others have said, and to address an error in your question...
PSIA is pounds per square inch absolute, NOT pounds per square inch atmospheric. Jack M. Kleinfeld, P.E. Kleinfeld Technical Services, Inc.
Infrared Thermography, Finite Element Analysis, Process Engineering

http://www.KleinfeldTechnical.com

 

[abeltio]

rebel,
JKEngineer's point is very important.
Answering your question as asked:
atmospheric pressure is a specific pressure.
i.e.: has a determined value of
0.0 psig = 14.69 psia = 1 atm
AT SEA LEVEL!
The question should have been: what is the difference between GAUGE and ABSOLUTE pressure?

1 atm is the atmospheric pressure at sea level.

Then:
0.0 psia = -14.69 psig (absolute vacuum)
also
psia = psig + 14.69psia

in layman terms:
the absolute pressure (psia) =
the pressure measured by a pressure gage (psig)
+
the atmospheric pressure in psi at that location (psia), at sea level the atmospheric pressure = 14.69psia.

HTH
Saludos.
a.