Like Queen, we’ve all been under pressure. Whether it’s a tight deadline at work or chores to finish around the house, there’s no denying that daily stress can pull us down like a heavy weight. Okay, so maybe it’s not a literal pressure, but you get the idea. Pressure, in the scientific sense, is defined as force per unit area, measured in pounds per square inch. While pressure may leave us feeling run-down and exhausted, it’s exactly what air compressors rely on to function.
When it comes to pressure in compressor systems, there are many different measurements, and it’s crucial to understand the differences between them. When discussing pressure with coworkers, plant managers or service technicians, it’s vital that everyone is using the same terms. Let’s take a look at a few common pressure terms and what they mean.
We already discussed the basic definition of pressure, which is the force per unit area measure in pounds per square inch (psi). Pressure can also be measured in pounds per square inch absolute (psai) and pounds per square inch gauge (psig). It’s important to ensure everyone is using the same units when looking at the following types of pressure.
Absolute pressure is the total pressure measured from absolute zero, or a perfect vacuum.
Pressure dew point, often called PDP, refers to the temperature air at a given pressure at which water begins to condense out. PDP changes with temperature and pressure, and it can greatly impact the quality of compressed air.
Discharge pressure is fairly self-explanatory; it’s the pressure at the discharge connection of a compressor, typically the point-of-use. Discharge pressure is not always the same as the operating pressure of a compressor. Often, it may be lower due to pressure drops.
A pressure drop indicates a loss of pressure in a compressed air system due to friction, restriction, leaks, or other factors. If you notice that your system has a considerable pressure drop, consider undergoing a compressed air audit to identify and repair inefficiencies.
Pressure range is the difference between the minimum and maximum pressures for an air compressor. It is also called the load/no load pressure range. Pressure range is indicated on compressor data sheets and is sometimes measured in bars (1 bar=14.5 psi).
Static pressure is the pressure measured in a flowing stream in such a manner that the velocity of the stream has no effect on the measurement. Static pressure can affect machine performance if the compressor is housed in a room with improper ventilation. A good indicator of negative static pressure is difficulty opening the compressor room door.
Pressure in air compressors is a good thing, and it’s important to understand the different types at work.