Class 1.6 and Class 2.5 pressure gauges for industrial production can be used as precision pressure gauges or digital pressure gauges if there is a requirement for precision measurement; pressure transmitters should be selected according to remote transmission or control requirements. If the range of the pressure gauge is correctly selected, the service life of the gauge can be extended. To measure fluctuating pressure, the maximum range should be 1.5 times of the measured value; to measure fluctuating pressure, the maximum range should be twice of the measured value.
Ordinary pressure gauge can be used for air, water, steam, oil, etc., with black casing; special pressure gauge is needed for certain media, such as yellow casing ammonia pressure gauge for ammonia; oxygen pressure gauge with sky blue casing; oxygen pressure gauge and acetylene pressure gauge are strictly prohibited. When the spring tube is contaminated by oil, carbon tetrachloride can be injected into the spring tube using a syringe and can be used only after cleaning.
For the pressure measurement of strong corrosive media and corrosive gas environment, such as dilute hydrochloric acid and hydrochloric acid gas, in addition to isolation, you can also choose all stainless steel pressure gauge, but all stainless steel pressure gauge is not applicable to the environment of corrosive media such as chlorine and nitric acid. Diaphragm pressure gauges are also available. Isolation diaphragms are available in a variety of materials, such as 0cr7ni12mo2 (316), Monel alloy (cu30ni70), Hastelloy (h276c), tantalum (TA) and fluoroplastic (F4), which can be selected according to the measurement medium.
Some isolation instruments have an indirect measurement structure. Depending on the nature of the medium to be measured, a working fluid (e.g. glycerin or silicone oil) fills the instrument or capillary tube to transfer the pressure. The instrument is suitable for measuring the medium pressure of high viscosity, easily crystallized, highly corrosive and high temperature liquids, gases or solids in suspension. For places with high vibration, Yn vibration resistant pressure gauge or marine pressure gauge should be used.
For occasions with remote transmission, alarm and interlocking requirements, pressure transmitters should be selected and the measured pressure should be transmitted to the display instrument or DCS card by current signal. Pressure transmitters have a wide range and are flexible in use. Pressure resistance and corrosion resistance should be considered.
The electric contact pressure gauge should be a magnetic auxiliary electric contact device with stable and reliable action and high contact power. Damping device is set inside the instrument to resist medium pulsation and mechanical vibration. The electric contact pressure gauge in the explosion-proof environment should be explosion-proof type.
Diaphragm pressure gauge can be selected for on-site micro-pressure measurement. Diaphragm pressure gauge is only suitable for measuring the micro-pressure of gas or liquid medium which is non-corrosive to copper and copper alloy.
