barg means bar-gauge (gage) bara means bar-absolute (including atmospheric pressure) bara = barg + atmospheric pressure (Atm), if 1 Atm = 1 bar, bara = barg + 1.
Also to know is, what is the difference between bar and bar g?
The difference between bar and barg is the difference in the reference you take. Measurement of pressure is always taken against a reference. It means that pressure difference is measured. If the reference is atmospheric pressure (1 bar) then pressure is cited in barg.
What is bar gauge?
Bourdon tube pressure gauges, vehicle tire gauges, and many other types of pressure gauges are zero-referenced to atmospheric pressure, which means that they measure the pressure above atmospheric pressure (which is around 1 bar); this is gauge pressure and is often referred to in writing as barg (spoken "bar gauge").