Diaphragm Pressure Gauge

A diaphragm pressure gauge is a precision instrument designed to measure the pressure of aggressive, viscous, or corrosive process media that would otherwise damage or contaminate a conventional Bourdon-tube gauge. At its core, a flexible diaphragm — typically manufactured from SS 316L stainless steel or PTFE — acts as a physical barrier between the process medium and the gauge's internal measuring mechanism. Pressure exerted by the process fluid deflects the diaphragm, and this deflection is transmitted hydraulically to the pointer assembly, providing an accurate pressure reading without any direct contact between the medium and the sensitive internal components.

The construction of a diaphragm pressure gauge is engineered for durability and reliability in demanding environments. The wetted parts — including the diaphragm and process connection — are fabricated from SS 316L stainless steel, offering excellent resistance to a wide range of corrosive chemicals. For highly aggressive media such as strong acids, alkalis, or solvents, a PTFE-lined diaphragm provides an additional layer of chemical inertness. The gauge case is glycerin-filled, which dampens the effects of vibration and pressure pulsation on the pointer and movement, significantly extending the instrument's service life and maintaining readability in dynamic process conditions.

Diaphragm pressure gauges are available across a broad pressure range, from 0–1 bar for low-pressure applications up to 0–400 bar for high-pressure processes. Dial sizes of 100 mm and 160 mm are offered to suit different installation requirements and readability needs. Mounting options include flush-mount flanges — ideal for hygienic or sanitary installations where no dead space should exist between the gauge and the process — as well as threaded flange connections for standard industrial pipework. The flush-mount design is particularly valued in food, beverage, and pharmaceutical applications where cleanability and compliance with hygienic standards are paramount.

In the chemical industry, diaphragm gauges are routinely used to monitor pressures in reactors, pipelines, and storage vessels handling acids, caustic solutions, and solvents. In food and beverage processing, they measure pressures in pasteurisers, homogenisers, and CIP (clean-in-place) systems, where hygienic design and ease of cleaning are critical. Pharmaceutical manufacturers rely on diaphragm gauges in sterile process lines, bioreactors, and filtration systems, where product purity and regulatory compliance demand instruments that leave no residue and resist microbial ingress. The combination of material versatility, hygienic design options, and robust construction makes the diaphragm pressure gauge an indispensable tool across these industries.

Typical accuracy for diaphragm pressure gauges is ±1.0% of full scale, meeting the requirements of most industrial measurement applications. Process temperatures up to 120°C can be accommodated, making these gauges suitable for steam-traced lines and elevated-temperature processes. All instruments should be selected with consideration for the specific process medium, operating pressure range, temperature, and connection standard to ensure optimal performance and longevity.