Diaphragm Pressure Gauge with Flange

• Product Description

A diaphragm pressure gauge is a system consisting of a diaphragm isolator and a general-purpose pressure gauge. It is suitable for measuring the pressure of highly corrosive, high-temperature, high-viscosity, easily crystallizing, easily solidifying, or media containing suspended solids, as well as in situations where the measured medium must be prevented from directly entering the general-purpose pressure gauge and where sediment accumulation and easy precipitating must be avoided. Custom designs are also available in stainless steel, sanitary, electrical contact, shock-resistant, flange, and diaphragm types. Diaphragm pressure gauges are mainly used in the petrochemical, alkali production, chemical fiber, dyeing, pharmaceutical, food, and dairy industries for measuring the flow rate and pressure of fluid media during production processes.

Working Principle

The working principle of a diaphragm pressure gauge is shown in the figure. A diaphragm pressure gauge is a system consisting of a diaphragm isolator and a general-purpose pressure gauge. A vacuum is created in the Bourdon tube using specialized equipment, and a filling fluid is introduced. The diaphragm is then sealed with a diaphragm. When the pressure P of the measured medium acts on the diaphragm, it deforms, compressing the working fluid inside the system. This working fluid forms a pressure ΔP equivalent to P. Through the conduction of the working fluid, the free end of the elastic element (Bourdon tube) in the pressure gauge undergoes a corresponding elastic deformation and displacement. The measured pressure value is then displayed according to the working principle of the matching pressure gauge.

Temperature Characteristics of Diaphragm Pressure Gauges

Because the diaphragm pressure gauge system uses a sealing fluid as the medium for transmitting pressure, the pressure gauge reading increases with the temperature of the pressure-bearing part due to the coefficient of thermal expansion of the sealing fluid. The amount of temperature influence is related to the coefficient of thermal expansion of the sealing body, the stiffness of the diaphragm, and the pressure temperature, especially for low-range pressure instruments. Generally, the temperature error of the pressure-bearing part is specified to be no more than 0.1%/degree. Therefore, the total temperature influence of the diaphragm pressure gauge is generally the sum of the temperature influence of the general-purpose instrument and the temperature influence of the pressure-bearing part of the diaphragm device.

Measure Range

0.1, 0.16, 0.25, 0.4, 0.6, 1, 1.6, 2.5, 4, 6, 10, 16, 25, 40, 60
-0.1~0, -0.1~0.06, -0.1~0.15, -0.1~0.3, -0.1~0.5,
-0.1~0.9, -0.1~1.5, -0.1~2.4

Application of Diaphragm Pressure Gauges

Before installing a diaphragm pressure gauge, it is essential to understand the characteristics of the medium being monitored. Diaphragm pressure gauges are specifically designed for special media. For monitoring the pressure of general gases, water, and oils, a general pressure gauge can be used. For monitoring the pressure of nitric acid, phosphoric acid, and strong alkalis, a stainless steel pressure gauge can be used. However, when the monitored medium is highly corrosive (e.g., hydrochloric acid, wet chlorine, ferric chloride); has high viscosity (e.g., latex); is prone to crystallization (e.g., brine); is prone to solidification (e.g., hot asphalt); or contains solid suspended matter (e.g., sewage), the above pressure gauges are unsuitable. This is because the SUS316 stainless steel tube will be corroded by hydrochloric acid, and the suspended matter in asphalt and sewage will clog the pressure gauge's guide hole, rendering the pressure gauge unusable. Because the diaphragm pressure gauge has a diaphragm, it can prevent high-viscosity, easily crystallizing, and easily solidifying media from flowing into the pressure guide hole, ensuring that the pressure gauge reading accurately reflects the pressure of the measured medium.