Absolute Pressure Formula

You have studied the concept of pressure before. It is the value of force applied to a particular area. The measurement is done based on the concepts and understanding of this physical quantity. In this section, we will discuss the absolute pressure formula. We will study and find out how absolute pressure is defined and calculated. For this, we will use a standard formula of absolute pressure and define every term in it. Let us proceed and find out what it means and how it differs from other pressure measurements.

What is Absolute Pressure?

You will find a plethora of measurement methods used to define, calculate, and determine different kinds of pressure. One such scientific term is absolute pressure. The absolute pressure formula fluids contain the terms atmospheric pressure and gauge pressure. The unit of this physical quantity is similar to that of all the pressure measurements. It is pound per square inch (psi).

Absolute pressure, as the name suggests, is the pressure calculated considering absolute zero pressure as a base. In space, there is no atmosphere. Hence, we do not feel any pressure in space. Hence, a vacuum can give you the value of absolute zero pressure. This is considered to be the base for all measurements related to absolute pressure.

The correct formula for absolute pressure depends on the reference we actually use to determine its value. Two scientific terms are used as a reference to measure absolute pressure. They are: 

• Absolute zero pressure

• Gauge pressure

In the case of absolute zero pressure, anything adding up from the zero level is called absolute pressure. We consider the value of absolute zero pressure is zero as in a vacuum. Scientists use this parameter to get the value of absolute pressure. They have formulated a device that can measure this physical quantity. In this device, the sensor has a diaphragm with a vacuum behind it. Hence, the pressure calculated by this device can be considered absolute pressure.

If the reference frame is gauge pressure then you will have to consider the value of the atmospheric pressure. The gauge, if not in a vacuum, will not show the existence of atmospheric pressure. We have to adjust its value by using the absolute pressure formula.  

What is the Formula of Absolute Pressure?

As per the convention, any pressure detected above the level of absolute zero pressure is called absolute pressure. The formula of absolute pressure is represented as follows.

Pabs = Patm + Pgauge

In this expression, Pabs = absolute pressure, Patm = atmospheric pressure, and Pgauge = gauge pressure. Now that you have understood how the absolute pressure formula fluid is calculated, you can easily put the values and find the solution to a problem given in an exercise.