Pressure Gauges

What is a Pressure Gauge?

A Pressure gauge is used to measure the intensity of a fluid which is flowing through a fluid line. Pressure gauges usually are devices which can be used to measure pressure of fluids like oil, hydraulic oil & other types of lubrication oil flowing through the channel. A fluid gauge is usually installed in the main line of any hydraulic system. Pressure gauges help to troubleshoot a machine as hydraulic machines are set to work in a proper range. Hence any leakage in the system would end up in destroying the whole process and would cause the machine to mal function. Due to this type of difficulties it is always important to use a pressure gauge for such instances.

Significance of Pressure Gauges

Pressure gauges have been used in fluid power systems for well over a hundred years, so it might be a surprise that pressure gauge designs continue to evolve. The evolution of pressure gauges for fluid power applications has, generally, been an increase in application specific features. For instance, pressure gauges are now more routinely designed with hydraulic friendly pressure connections (such as SAE/Metric straight threads) to prevent system leaks. Analog gauges with custom scales are more common and digital pressure gauges with customizable firmware allow process measurement of pressure-based measurement of leaks or other parameters like torque, load, force and hardness.

Pneumatic and compressed air systems are also rife with gauges, as pressure is also measured in many locations throughout the system. Pressure is measured at the receiver(s), as well as at every FRL or stand-alone regulator in the system. Sometimes pressure is measured at pneumatic actuators as well. Typically, pneumatic pressure gauges are rated for not much more than 300 psi, although typical systems run around 100 psi.

Types of Pressure Gauges

Pressure is measured in three ways—absolute, gauge and vacuum. Absolute pressure is a measure of actual pressure including ambient air, which is zero-referenced with a perfect vacuum, but can be as high as 14.7 psi at sea level. Absolute pressure readings are considered in applications interacting with ambient air, such as the compression ratio calculation for flow (cfm) requirements. Gauge pressure is zero-referenced against ambient pressure and is used in most applications operating in, but not with, ambient air, such as in fluid power systems. Disconnected from equipment, gauge pressure will read zero. Finally vacuum "pressure" is expressed in Torr, or referenced against ambient pressure, as with "in.-Hg" (inches of mercury) units, which measures pressure below ambient.

The hydraulic gauge can withstand different pressure ranges based on what type of gauge style it is and what material it is made out of. Because of this, the gauge style and the material make up two of the most important selection criteria for gauges.

They are many types of gauge styles, the most common being Bourdon tubes and bellow gauges. Bourdon tubes function by taking the pressure and converting it into mechanical energy.