Absolute Pressure Formula

Absolute pressure is a sort of pressure measurement in which a complete vacuum is maintained. Such ranges are frequently labelled with the letter ‘abs.’ When we go out strolling on a windy day and the wind is strong enough to feel its force, it’s actually the air molecules that are ricochet off of you are causing this sensation. We may refer to this as the atmospheric pressure, which is the sum of the forces exerted by air molecules per unit area. This pressure is frequently expressed as psi (pounds per square inch) (psi).

Absolute pressure is the pressure measured in relation to absolute zero pressure in a vacuum. Negative pressure, often known as vacuum pressure, is a measurement of pressure below atmospheric pressure.

Formula

P_abs = P_atm + P_gauge

where,

• P_atm denotes the atmospheric pressure.
• P_gauge denotes the negative pressure.

Sample Problems

Problem 1. Find the absolute pressure for gauge pressure 29 psi and atmospheric pressure 13 psi.

Solution:

Since, P_abs = P_atm + P_gauge

Here, P_atm = 13 psi and P_gauge = 29 psi

= 13 + 29 psi

= 42 psi

Problem 2. Find the absolute pressure for gauge pressure 45 psi and atmospheric pressure 20 psi.

Solution:

Since, P_abs = P_atm + P_gauge

Here, P_atm = 45 psi and P_gauge = 20 psi

= 45 + 20 psi

= 62 psi

Problem 3. Find the gauge pressure for an absolute pressure of 43.5 psi and atmospheric pressure 14 psi.

Solution:

Since, P_abs = P_atm + P_gauge ⇒ P_gauge = P_abs – P_atm

Here, P_abs = 43.5 psi and P_atm = 14 psi

= 43.5 – 14 psi

= 29.5 psi

Problem 4. Find the gauge pressure for an absolute pressure of 56 psi and atmospheric pressure 37.8 psi.

Solution:

Since, P_abs = P_atm + P_gauge ⇒ P_gauge = P_abs – P_atm

Here, P_abs = 56 psi and P_atm = 37.8 psi

= 56 – 37.8 psi

= 18.2 psi

Problem 5. Find the absolute pressure for gauge pressure 89 psi and atmospheric pressure 55 psi.

Solution:

Since, P_abs = P_atm + P_gauge

Here, P_atm = 55 psi and P_gauge = 89 psi

= 55 + 89 psi

= 144 psi