Measurement Equipments

Pressure Sensor

See where your pressure goes, from compressor room to machine, and stop paying for pressure you don't need.

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A stainless steel pressure sensor with a threaded process connection and an angled cable plug

Product overview

Know the pressure at every point in your plant

Our pressure sensor turns the pressure of your compressed air or technical gas into a continuous electrical signal, read by a data logger, building management system, compressor master controller or portable instrument. Pressure becomes a recorded, time-stamped value you can trend, alarm and analyse from anywhere in the plant.

Inside, a thin metal diaphragm or silicon chip bends by just a few micrometres under pressure, changing the resistance of strain-sensitive resistors bonded to it. With no moving parts to wear, it gives you a 4–20 mA or 0–10 V signal, or a digital value over Modbus RTU, Modbus TCP or IO-Link. Gauge, absolute and differential versions measure against the atmosphere, a vacuum or a second point.

Fitted at the right points, sensors show the pressure your compressors deliver, the pressure lost in treatment and distribution, and the pressure your machines actually receive. Those figures show where energy is being wasted, and whether your production equipment gets the pressure it was designed for.

A pressure sensor with a digital display reading bar and °C above a stainless steel connection
  • 4–20 mAOutput that reveals a broken wire
  • About 7 %More compressor energy for each extra 1 bar
  • 12.5 %Less air lost through leaks from 7 to 6 bar g
  • Below 10 %Best-practice pressure drop, compressor to point of use

Benefits

The problems it solves

Pressure is what your whole air system is controlled by, and pressure loss is where much of its energy is wasted. Here is what goes wrong without measurement, and how the sensor fixes it.

  • Setpoints set by habit

    The problem

    Without measured data, setpoints creep up to satisfy the worst point in the network, and each additional 1 bar raises compressor energy by about 7 %.

    How it solves it

    Logged pressure shows how much your machines actually need, so you can lower the setpoint safely and cut the air lost through every leak.

  • Low pressure at the machine

    The problem

    Raising the setpoint to cure a 1.5 bar drop across loaded filters or a restrictive hose costs energy plant-wide, and still leaves the machine short at peak demand.

    How it solves it

    Readings along the air path locate the filter, dryer, pipe section or hose wasting pressure, so you remove the restriction instead.

  • Faults that come and go

    The problem

    Dips lasting a few seconds, overnight pressure decay and filter loading that builds over months never coincide with an inspection round.

    How it solves it

    Continuous, time-stamped logging captures dips and spikes lasting seconds, and explains intermittent machine faults.

  • Leakage with no figure

    The problem

    Leaks hide throughout the network, and a repair programme cannot be costed until the leakage is measured.

    How it solves it

    A pressure decay test turns a pressure trend into leakage: a 10 m³ system falling from 7 to 6 bar g in 5 minutes leaks about 2.0 m³/min of free air.

  • Running out of air

    The problem

    Low pressure causes rejects, and loss of instrument air drives control valves to their fail-safe positions.

    How it solves it

    Low-pressure alarms warn your operators, start a standby compressor or stop a process before it runs out of air.

  • Erratic compressor control

    The problem

    An inaccurate, drifting or poorly placed sensor makes compressors start unnecessarily, run unloaded or let pressure fall below what production needs.

    How it solves it

    An accurate signal from the right location narrows pressure bands and avoids unnecessary compressor starts.

Where it’s used

Wherever pressure matters to production

Every compressed air system is controlled by pressure. These are some of the places our sensors keep watch over it.

  • Robots welding a car body on an assembly line

    Automotive and general manufacturing

    Network and point-of-use sensors confirm that assembly tools, robots and clamping cylinders receive their rated pressure.

  • Wine bottles moving along a bottling line

    Food, beverage and packaging

    Supply pressure to filling, capping, labelling and bottle-blowing machines, with alarms before low pressure causes rejects.

  • Yellow tablets spilling from a medicine bottle

    Pharmaceuticals

    Pressure records that form part of the batch documentation for tablet coating, granulation and filling equipment.

  • Test tubes of coloured chemicals in a laboratory rack

    Oil, gas and petrochemicals

    Low-pressure alarms and trips on instrument air headers, before control valves move to their fail-safe positions.

  • Electricity pylons and power lines at sunset

    Power generation

    Monitoring of instrument air, switchgear air receivers and soot-blowing air.

  • A row of yarn winding machines in a textile mill

    Textiles

    Air-jet looms that consume large volumes of air, where weaving quality depends on a stable supply pressure.

Also compressor rooms in every industry, PET bottle production at 30–40 bar g, medical gas pipelines, natural gas, CNG and hydrogen, glass, steel and cement, rail brake systems, nitrogen and oxygen generators, and test benches and laboratories.

How it works

Bend, sense, signal

Line pressure bends a steel diaphragm by a few micrometres. Strain gauges on it turn that bend into an electrical signal your controller can read.

How a pressure sensor works: air from the main reaches the sensor through a tapping and an isolation valve and bends a thin stainless steel diaphragm by a few micrometres. Strain gauges at its centre are stretched and those at its rim compressed; wired in a Wheatstone bridge they give a millivolt signal, which the electronics amplify, linearise and temperature-correct and send as a 4–20 mA signal to a logger or controller. +V0 V 7 bar g 11 mA Air mainIsolation valve Diaphragm, magnified≈ 3 µm at 16 bar Wheatstone bridgemV Signal conditioning 4–20 mALogger or controller4 mA → 0 · 20 mA → 16 bar g 12345 Compressed airLine pressureGauge stretchedGauge compressed4–20 mA signal

  1. 1. Pressure inAir reaches the sensor through a tapping on the top of the pipe and an isolation valve, and presses on the underside of a thin stainless steel diaphragm. A gauge sensor vents the other side to atmosphere, so it reads zero at ambient pressure.

  2. 2. The diaphragm bendsThe diaphragm bulges by only micrometres: about 3 µm at the centre for a 6 mm diaphragm, 0.33 mm thick, at 16 bar. It stays well inside its elastic range, so it returns exactly to shape, with nothing to wear.

  3. 3. Strain to resistanceStrain gauges at the centre are stretched while those near the clamped rim are compressed. Wired in a Wheatstone bridge, their opposite changes add up to a millivolt output, while temperature effects common to all four cancel out.

  4. 4. ConditionThe electronics amplify, digitise, linearise and temperature-correct the bridge signal, using correction coefficients stored for each sensor during manufacture.

  5. 5. Signal outThe sensor sends a 4–20 mA current: on a 0–16 bar g sensor, 4 mA at zero, 11 mA at 7 bar g and 20 mA at 16 bar g. A reading below 4 mA reveals a broken wire. Modbus or IO-Link can send the value digitally instead.

Example figures for a 0–16 bar g sensor with a 4–20 mA output and a thin-film stainless steel diaphragm.

Get the full details

Our brochure covers it in detail, and our questionnaire tells us what we need to recommend the right one for your plant.

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