Pressure Basics – Air and Hydrostatic

Air compressors are relatively common machines that have practically become a household item owing both to its increasingly affordable price as well as the various functions it’s capable of performing from pumping bicycle tires to air-cleaning to the running of air tools. Loosely speaking, air compressors consist of a compressor unit which compresses the air and an air tank which stores the compressed air.

Various air compressors have different capabilities and run at different capacities, with the high-end ones naturally having superior specifications. Air pressure is built-up, with the upper limit of the given machine more often than not reflecting its price. Depending on the region, it is denoted by either pounds per square inch (psi), kilogram force per square centimeter (kgf/cm²), or megapascal (Mpa).

Standard air pressures generally range from around 0.7 Mpa to 3 Mpa. Many smaller DIY-type pneumatic tools, such as nail and staple guns, will run on 0.4 to 0.7 Mpa, whereas higher end professional-grade tools will require much more pressure. The standard SI measurement for pressure is the pascal, but some countries like the USA use psi. 1 Mpa is equal to roughly 145 psi, or 10.2 kgf/cm². This will help you convert pressure units into whatever you’re most familiar with.

Hydrostatic Pressure

This is the term used to describe the pressure a fluid exerts on its surroundings due to the force of gravity. Modern pipe lines utilize mechanical pumps to maintain a certain pressure within the pipes. This ensures that there is sufficient pressure when consumers turn on their taps. But hydrostatic pressure is fundamentally different in that it’s “natural” pressure as opposed to mechanized pressure.