A pressure gage is a measuring device for liquid strength. For installation and tuning of fluid power machines, pressure gages are necessary and are essential for troubleshooting them.
Fluid power systems are both unstable and unreliable without pressure gauges. WIKA pressure gauges ensure that no leaks or pressure changes can affect the hydraulic system’s operational condition. The hydraulic system is designed to operate within a set pressure range so that the gauge must be rated within that range. Hydraulic pressure gauges are available to measure up to 10,000 psi, although the maximum hydraulic pressure is typically between 3,000 and 5,000 psi.
Hydraulic gauges are often installed at or near the pressure port of the pump to indicate the system pressure, but can be installed anywhere on the machine where the pressure needs to be monitored especially if the sub-circuits operate at a pressure different from the pump pressure, such as the lowering valve.
Often, pressure-reducing valves have a gauge port in which to tap, allowing you to directly monitor the downstream pressure setting.
Pressure gauges have been used in fluid power systems for over a hundred years, so it might come as a surprise that the design of the pressure gauge continues to evolve. In general, the development of pressure gauges for fluid control applications has expanded the application of specific features.
For example, pressure gauges are now more widely equipped with hydraulic-friendly pressure connections (such as SAE / Metric straight threads) to avoid device leakage.
Analog gauges with custom scales are more common and electronic pressure gauges with customizable firmware allow the measurement of pressure-based leakage measurements or other parameters such as torque, charge, strength and hardness.
Pneumatic and compressed air systems are also filled with gauges, as pressure is also measured at many points throughout the process. Pressure is assessed at the receiver(s) as well as at any FRL or stand-alone regulator in the process.
Pressure is sometimes also measured at pneumatic actuators. Usually, the pneumatic WIKA Pressure Gauge is rated at not more than 300 psi, although the standard systems operate about 100 psi.
Pressure is assessed in three ways absolute, gage, and vacuum. Absolute pressure is a measure of actual pressure, including ambient air, which is zero with perfect vacuum, but can be as high as 14.7 psi at sea level.
Absolute pressure measurements are considered for applications dealing with ambient air, such as the measurement of the compression ratio 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 fluid power systems.
Disconnected from the device, the gage pressure reads zero. Finally, the vacuum “pressure” is expressed in Torr, or referenced against ambient pressure, as with “in.-Hg” (inches of mercury) units, which measure the pressure below the ambient.
The hydraulic gauge can withstand different pressure levels depending on what type of gauge design it is and what material it is made of. Because of this, the gage style and the material make up two of the most important selection criteria for gauges.
There are many types of gauge styles, the most common being Bourdon tubes and bellow gauges. The Bourdon tubes work by taking the pressure and converting it to mechanical energy.
This force pushes the dial in the gage, indicating the actual amount of pressure in the process. Bourdon tube gauges are actually some of the most common gauges and have different configurations, such as curved, helical and spiral gauges.
The different types of tubing, the width of the tube and the material made out of it all vary depending on the pressure level. The cross section of the tubing shifts with increasing pressure is an important feature to remember. Typically, as the working stress of the meter increases, the form of the cross section of the pipe layout can gradually change from an oval shape to a circular shape.