How to Calculate Internal Pressure

Pressure is measured in pounds per square inch (psi).

An internal pressure reading tells you the force that is being exerted by a substance that is contained inside a sealed area. To calculate this force, you need a barometer. The barometer must be inserted into the pressurized area and sealed so as to not expose the contents to external atmospheric pressures; doing so would result in the depressurization of the contents, resulting in an inaccurate reading.

Things You'll Need

• Barometer

Instructions

1. Examine the pressurized area to determine if a barometer is already in place. Most modern-day pressurized substances already contain a barometer for safety. Note this reading.

2. Insert a barometer into the pressurized area if none is in place. Almost all pressurized cylinders, tanks and liquid pipes are designed to have a barometer placed into the valve used to insert or refill the substance. Examples include valve stems on tires and screw-on valve barometers for air cylinders. Take a reading.

3. Convert the pounds per square inch reading to other units as required using the ratios 1 psi is equal to 6.89 kilopascals and 144 feet/lbs.

References

• Engineers Edge: Pressure Vessel Wall Thickness with Internal Pressure Applied Calculator