There are mainly two kinds of pressure gauges, one is mechanical and the other is electronic. Mechanical pressure gauges are divided into Bourdon tube pressure gauges, capsule pressure gauges, differential pressure gauges, diaphragm pressure gauges, diaphragm pressure gauges, and so on. In our practical work, we generally need to confirm the following parameters for model selection:
I. dial diameter
The diameter of the gauge is the diameter of the case by default. Generally, the commonly used ones are 1.5”, 2”, 2.5”, 3”, 4”, 6”, 8”, 10”, etc.
II. shell material
The case material of the pressure gauge includes ABS (engineering plastic), carbon steel (usually with color coating or chrome plated), 304 stainless steel and some customized materials. The case material should be chosen according to the working environment.
III. connection tube
The connection tube of pressure gauge is divided into axial (back connection) and radial (bottom connection). If it is panel mounted, gauge with flange could be chosen.
IV. measuring medium
Generally, there are only two kinds of wetted materials of pressure gauge: copper alloy or 304 stainless steel. If the medium you measure is not applicable or corrosive to these two kinds, Then diaphragm-seal pressure gauge could be chosen. It composed of a diaphragm isolator and a general pressure gauge. The diaphragm isolator is to effectively prevent the measuring medium from contacting with the measuring element. When the pressure P of the measuring medium acts on the diaphragm, the diaphragm deforms and squeezes the sealing liquid of the pressure measuring system, producing a pressure of P-△P. When the rigidity of the diaphragm is small enough, △P will also be small, and the pressure inside the pressure measuring system is close to the pressure of the measuring medium.Then the gauge will show the pressure of the measuring medium.
V. liquid filling
In some environments with large mechanical vibration, you could choose Vibration-Resistant Pressure Gauges. The function of the liquid (mainly glycerin or silicone oil) in the gauge is to increase resistance and effectively prevent the pointer from constantly shaking, so that we could accurately read the pressure value. Generally, it is commonly used near the pump or in the environment with vibration.
VI. medium temperature
The maximum measuring medium temperature of copper alloy measuring elements is +80℃, and that of stainless steel is +200℃s. However, if the pressure gauge you choose is a liquid filled and shock resistant pressure gauge, the maximum temperature of the medium at this time should not be higher than +100℃. and you should choose silicone oil as the filling liquid. If the temperature is higher than +100℃, you could use radiators to cool down the temperature.
VII. range
The pressure gauge drives the pointer to rotate through the deformation of the measuring element and the amplification mechanism, so as to display the pressure value. We should pay attention to the pressure range. Generally, the maximum pressure measured is 3/4 or 2/3 of the range of the pressure gauge. If the range is much higher than your working pressure, the change of the pointer is small, and the pressure reading is inaccurate. If the range is lower than your working pressure, the pressure gauge may be damaged due to overload.
VIII. Connection size
Different thread standards are used in various countries. The mainly used threads standards are M, G, PF, BSPP, BSPF, NPT, APT, R, BSPT, PT, ZG and so on.
Post time: Jul-19-2022