What is the difference between gauge pressure and absolute pressure?

What is the difference between gauge pressure and absolute pressure? 

Solution:

Difference between Gauge Pressure and Absolute Pressure

	Gauge Pressure	Absolute Pressure
1.	Gauge pressure is defined as the pressure relative to barometric or atmospheric pressure.	Absolute pressure is defined as the pressure of having no matter inside a perfect vacuum of space.
2.	It doesn’t take atmospheric pressure into account. It is equal to Absolute pressure minus atmospheric or ambient pressure.	It is the addition of atmospheric pressure and gauge pressure. It is used for the calculation of atmospheric pressure
3.	It uses atmospheric pressure (14.7 PSI) as its Zero point.	Calculations that took in absolute pressure and use this absolute zero as their reference point.
4.	It cannot be used in gas law calculations as it doesn’t reflect accurate pressure but rather a difference in pressure.	It gives accurate barometric or atmospheric pressure when sealed in a high vacuum behind the detecting diaphragm.
5.	It is greatly influenced by changes in altitude or weather conditions in atmospheric pressure.	It doesn’t get influenced by any external changes in atmospheric pressure.
6.	The formula of Gauge pressure is given by, pg = ps – patm ,   (Where pg is gauge pressure, ps is system pressure and Patm is atmospheric pressure)	The formula of Absolute pressure is given by: pa = pg + patm  (Where pa is absolute pressure, pg is gauge pressure and Patm is atmospheric pressure)
7.	It is used in machines like Well pumps, Air compressors, and Tire gauges.	It is used for leak testing in a totally sealed container, smartwatches, and navigation systems for altimeter measurements.
8.	A manometer is a device used to measure gauge pressure.	Mercury Barometer is the device used to measure atmospheric pressure.