What is the Difference Between Gauge Pressure and Atmospheric Pressure?

The difference between gauge pressure and atmospheric pressure lies in their measurements and the reference points they are zero-referenced against.

Gauge Pressure:

Gauge pressure, also called overpressure, is the pressure of a system above atmospheric pressure.
It is zero-referenced against ambient air (or atmospheric) pressure, meaning gauge pressure readings include the pressure from the weight of the atmosphere.
Gauge pressure is independent of atmospheric pressure and does not change with elevation, as it always takes local atmospheric pressure into account.
Gauge pressure is suitable for measuring pressure in pipes and tanks where the pressure is higher than atmospheric.

Atmospheric Pressure:

Atmospheric pressure, also known as barometric pressure, is the force that air above a surface exerts on that surface.
It changes with altitude and is affected by weather conditions.
Atmospheric pressure at sea level is 1.013 bar (14.7 psi).

In summary, gauge pressure is a measure of the pressure above atmospheric pressure, while atmospheric pressure is the force exerted by the air on a surface. Gauge pressure is independent of atmospheric pressure and is suitable for measuring pressure in pipes and tanks. On the other hand, atmospheric pressure changes with altitude and weather conditions.

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What is the Difference Between Gauge Pressure and Atmospheric Pressure?

Comparative Table: Gauge Pressure vs Atmospheric Pressure

Here is a table comparing gauge pressure and atmospheric pressure:

Parameter	Gauge Pressure	Atmospheric Pressure
Definition	Gauge pressure is the pressure relative to atmospheric pressure, measured in relation to the local atmospheric pressure. Atmospheric pressure is the force that air above a surface exerts on that surface, measured at sea level as 1.013 bar or 14.7 psi.
Symbol	psig, barg	psia, bara
Reference Pressure	Local atmospheric pressure	Absolute zero pressure
Direction	Gauge pressure is positive for pressures above atmospheric pressure and negative for pressures below it. Atmospheric pressure decreases as altitude increases.
Measurement	Gauge pressure is measured using pressure gauges and sensors, which have a sensing element such as a diaphragm that deflects due to pressure change. Atmospheric pressure is measured using highly precise digital gauges that utilize micro-electromechanical sensors.
Use	Gauge pressure is commonly used for measuring pressure in pipes, tanks, and other enclosed systems where the pressure is higher than atmospheric pressure. Atmospheric pressure is used for general weather observations and other atmospheric measurements.

Remember that the sum of gauge pressure and atmospheric pressure is the absolute pressure.

Guilherme Mazui

Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.