What is a pressure gauge and what is it used for
A pressure gauge is a measuring instrument that shows the pressure of a liquid or gas relative to atmospheric pressure. It is the most widely used instrument in industry: you will find one on every compressor, pump, boiler, hydraulic power unit, gas installation and pipeline, because pressure is the parameter that reveals a fault, blockage or overload fastest. Pressure gauges need no power supply, are read directly on site and, when correctly specified, run for years without servicing. That is why they remain the basis of pressure measurement despite the spread of electronic transmitters.
How a pressure gauge works
Most industrial pressure gauges use a Bourdon tube. A curved tube with an elliptical cross-section tends to straighten under pressure, and this small movement is transferred to the pointer through a segment and pinion. For low pressures up to 600 mbar a capsule (diaphragm) element is used, as it is more sensitive to small changes. The material of the measuring element determines which media the gauge can handle: brass for non-aggressive media, AISI 316L stainless steel for aggressive ones, and for the most chemically demanding media a diaphragm seal is fitted between the process and the gauge.
Types of pressure gauges in the Fadip range
Standard pressure gauges have a steel case and a brass measuring system and cover most applications on water, air, oil and neutral gases.
Glycerine filled pressure gauges dampen vibration and pressure pulsation, which makes them the first choice for pumps, compressors and hydraulics.
All stainless steel pressure gauges Type A, in dry and glycerine filled versions, are designed for the chemical, food and pharmaceutical industries and for outdoor installation. The bayonet version allows servicing on site.
Safety pattern pressure gauges with a solid baffle wall and blow-out back are mandatory on oxygen, acetylene and high pressures.
Contact pressure gauges also provide an electrical signal for alarms or pump control, while low pressure (millibar) gauges measure low pressures on gas installations, burners and ventilation.
How to choose a pressure gauge
Five parameters need to be defined. The measuring range should be chosen so that the working pressure falls between one third and two thirds of the scale. A gauge that constantly runs at the end of its scale quickly loses accuracy.
The dial size (40 to 250 mm) depends on the reading distance and the required accuracy class: class 2.5 for small dials, 1.6 for 100 and 160 mm, and 1.0 for test gauges.
The connection is usually G1/4" or G1/2", bottom or back entry, with M20x1.5 and NPT available on request. The medium and temperature determine the material and whether a siphon, diaphragm seal or glycerine filling is needed, while the operating conditions (vibration, outdoor installation, explosive atmosphere) determine the case design and ingress protection. For a detailed guide with examples, see How to choose the right pressure gauge.
Technical specifications
Fadip pressure gauges are made to EN 837-1 in dial sizes of 40, 50, 63, 80, 100, 160 and 250 mm. Measuring ranges run from vacuum (-1...0 bar), through compound scales, up to 0...1000 bar, and millibar versions cover low pressures up to 600 mbar. Dials are available in bar, MPa, kPa, psi or dual scales, with an optional red limit mark and the customer's logo. Cases are made of steel or AISI 304 stainless steel, measuring systems of brass or AISI 316L, ingress protection is up to IP65, ambient temperature -20 to +60 °C and medium temperature up to +200 °C with suitable installation. Contact versions offer magnetic, inductive and electronic contacts, including versions for ATEX zones.
Pressure gauge applications by industry
In hydraulics and pneumatics pressure gauges monitor power units, presses and air lines, while in water supply and heating they sit on booster sets, pumping stations, boilers and heat substations. In compressor stations they monitor receiver and filter pressure. Gas engineering uses millibar gauges on regulators and burners, the chemical and food industries use stainless and safety pattern versions, and agriculture and construction rely on glycerine filled gauges on sprayers, machinery and concrete pumps. Fire protection systems, medical gases and laboratories require safety pattern designs and class 1.0 instruments.
Pressure gauge calibration and servicing
A pressure gauge is a measuring instrument and its accuracy changes over time due to Bourdon tube fatigue, pressure surges or overload. Fadip operates an accredited calibration laboratory and issues calibration certificates for new and existing instruments of any make. The recommended interval is 12 months in normal use, or 6 months for instruments under pulsating loads and in safety functions. Alongside calibration we also carry out servicing: window replacement, glycerine refilling, zero adjustment and replacement of the measuring system.
Why buy from a manufacturer
As a manufacturer rather than an importer, Fadip supplies standard pressure gauges from stock and builds non-standard ranges, dials, connections and designs to specification at short notice, with no minimum import quantities. Technical support comes with direct access to production, spare parts and servicing are available for the whole life of the instrument, and calibration is done in-house.
Alongside pressure gauges we offer the complete range of accessories: valves and diaphragm seals, siphons and adapters, as well as thermometers and pressure transmitters for systems that need an electronic signal.
For a quotation, send us the working pressure, medium, temperature, dial size and connection. Our technical team will recommend a suitable pressure gauge within 24 hours. Contact us.
