An air pressure gauge is an instrument used for measuring the pressure. It is used in pneumatic systems like air compressors, air cylinders, air supplies and filling systems. It is useful for monitoring and testing pneumatic systems. An air pressure gauge can measure pneumatic and hydraulic pressure of gases, compressed air and low viscosity non-aggressive fluids. This article provides a guide to using an air pressure gauge in a pneumatic system.
Pneumatic and hydraulic systems
Pneumatics and hydraulics use the fluid power in order to operate. In pneumatics, compressed gases are used. In hydraulics, relatively incompressible liquids like oils are used. The gas in pneumatics absorbs the force while the liquid in pneumatics directly transfers the force. In order to control, monitor and test the pressure in these types of systems, the air pressure gauge instrument is used.
How is the air pressure measured?
There are absolute pressure and gauge pressure. The absolute pressure is measured zero against perfect vacuum. The gauge pressure is measured as a reference to the ambient barometric pressure. This means that the gauge pressure equals the absolute pressure minus the atmospheric pressure. There are different units that the pressure is measured with. These are bar, pascal (Pa), technical atmosphere (at), atmosphere (atm) and pound-force per square inch (psi).
How does the air pressure gauge work?
The main element of the air pressure gauge is the bourdon tube. It is a hollow tube sealed in one end and it gets flexed when the pressure is applied. Since this tube is bent in an almost circular shape when the pressure is applied, the tube's natural behaviour is to try and straighten out. Due to this movement of the tube which is connected to geared movement, and with the help of small gears, the pointer indicates the pressure on the dial of the gauge. This is the basic idea of the gauge. It is a very simple mechanism and as it is well known, the simplest solutions are usually the best. There are improved gauges but which are still based on this principle. The improvement is in the precision of the display where digital displays are implemented.
How to choose an air pressure gauge?
Firstly, the range and the accuracy of the instrument should be considered. Other important characteristics are the material with which it is constructed. You should ensure that it will be able to resist the conditions in which it will operate.