Digital Pressure Gauges in Australia: Types, Accuracy and How to Choose

A digital pressure gauge replaces the pointer and dial of a traditional gauge with a sensor, a microprocessor and a liquid crystal display. You read a number instead of estimating a needle position, and most models add features an analogue gauge cannot offer, such as selectable units, minimum and maximum recording and data logging. This guide explains how digital pressure gauges work, what the accuracy figures really mean, how to choose the right range and connection, and where each type of gauge fits in an Australian workshop, plant or laboratory.

What is a digital pressure gauge?

A digital pressure gauge measures the pressure of a gas or liquid and shows it as a numeric reading. Inside the body sits a pressure sensor, usually a strain gauge or piezoresistive element bonded to a diaphragm. When pressure flexes the diaphragm, the sensor produces a tiny electrical signal. The electronics amplify and correct that signal, then convert it to a reading in the unit you have selected.

This is the main difference from a Bourdon tube gauge. A Bourdon gauge uses a curved metal tube that straightens slightly under pressure and moves a pointer through a set of gears. It has no electronics, needs no battery and has been trusted in industry for well over a century. A digital gauge trades that mechanical simplicity for resolution, repeatability and data. If you want to compare the two approaches in more detail, our guide to liquid filled and dry pressure gauges covers the mechanical side.

Digital vs analogue pressure gauges

Neither type is better in every situation. The right choice depends on what you are measuring and what you need to do with the reading.

• Resolution: a digital gauge can display several digits, so small changes are visible. An analogue dial is usually read to the nearest graduation.
• Accuracy: good analogue gauges for process work are typically specified at 1.0% to 2.5% of full scale. Digital gauges commonly reach 0.5% or better, and laboratory instruments reach 0.025% of full scale.
• Units: a digital gauge lets you switch between bar, kPa, psi and other units at the press of a button. An analogue dial is printed in fixed units, often a dual scale such as kPa and psi.
• Data: minimum and maximum recording and optional data logging are digital features. An analogue gauge shows only the current value, apart from specialist designs with a high point indicator.
• Power and environment: analogue gauges need no power and tolerate harsh sites well. Digital gauges rely on a battery and electronics, so their ingress protection rating and temperature limits matter.
• Vibration and pulsation: a liquid filled analogue gauge damps a jumpy needle. A digital gauge can show a flickering last digit on a pulsating line, so check how the gauge handles rapid change.

Many sites use both. Permanent analogue gauges stay on the plant as a quick visual check, while a portable digital gauge is used for testing, commissioning and fault finding.

Understanding accuracy: what does 0.25% FS mean?

Accuracy on a datasheet is normally given as a percentage of full scale, written as % FS. It describes the largest error you should expect anywhere across the range, expressed as a share of the top of the range.

Take a 0 to 100 bar gauge with 0.25% FS accuracy. The permitted error is 0.25% of 100 bar, which is 0.25 bar, at every point on the scale. At 100 bar that is a tiny 0.25% error, but at 10 bar the same 0.25 bar error is 2.5% of the reading. This is why a gauge works best when your normal operating pressure sits in the middle of its range rather than near the bottom.

The accuracy values on the digital gauges we stock show how wide the spread is:

• PDK PDR100: 0.5% FS
• PDK PDR250: 0.25% FS
• PDK PDR500: up to 0.1% FS
• PDK PDR1000: 0.025% FS
• Baroli BD Series: 0.125% or 0.25% FS (best fit straight line)

Higher accuracy usually means a higher price and often a larger display. A general maintenance task rarely needs 0.025%, but a calibration laboratory checking other instruments does. A useful rule is that the reference gauge should be several times more accurate than the device it is checking. We explain this in our article on pressure gauge calibration in Australia.

How to choose the right pressure range

Choosing a range is the step most buyers get wrong. The aim is to size the gauge so that normal pressure falls comfortably inside the range, with room above it for spikes.

1. Find your maximum working pressure. Include any relief valve setting or pump deadhead pressure, not only the usual running value.
2. Leave headroom. Common guidance, such as that in EN 837-2, suggests keeping steady pressure at no more than about 75% of full scale and fluctuating pressure at no more than roughly two thirds. Check the guidance that applies to your own installation.
3. Do not oversize. A 0 to 700 bar gauge on a 20 bar line gives poor resolution and a larger absolute error.
4. Decide on vacuum. If the system can go below atmospheric pressure, choose a compound range, such as the PDR100 option of -1 to 2 bar.
5. Confirm the pressure type. Gauge pressure is measured relative to atmosphere. Absolute pressure is measured relative to a perfect vacuum. Most workshop and hydraulic tasks use gauge pressure.

Unit conversion helps when specifications are written in different units. One bar equals 100 kPa, 0.1 MPa and about 14.5 psi. A selectable-unit digital gauge removes the arithmetic entirely, which cuts transcription errors on service sheets.

Process connections and thread types

A gauge is only useful if it fits the system. Australian industry uses a mix of thread standards, so check the port before you order.

• BSPP (G threads): parallel British Standard Pipe threads that seal with a washer or bonded seal. The PDK PDR100, PDR250 and PDR500 digital gauges use a G1/4″ BSPP male bottom-entry connection.
• BSPT: tapered British Standard Pipe threads that seal on the thread. Several of our liquid filled analogue gauges use 1/4″ or 3/8″ BSPT.
• NPT: American tapered pipe thread, common on imported equipment. The Baroli BD Series is available in 1/4″ BSP or NPT and 1/2″ NPT.
• UNO and other fittings: found on hydraulic test points and hoses.

If your equipment mixes standards, a test kit with several adaptors saves time. The PDR Digital Pressure Test Kit pairs a PDK PDR100 or PDR250 gauge with 1/4″ BSPP, 1/8″ NPT, 1/4″ NPT, 7/16″ UNO and 9/16″ UNO male connectors and a 2 metre hose.

Features worth paying for

Selectable units

The PDK range offers units including mbar, bar, MPa, mmH2O, inHg, mmHg, kgf/cm2, atm, psi and kPa. This is valuable when you work across equipment from different manufacturers or countries.

Minimum and maximum recording

Min/max memory captures the highest and lowest pressure seen during a test. It is useful for finding pressure spikes in a hydraulic circuit or confirming that a relief valve opens where it should. See our guide to digital hydraulic pressure gauges for practical test examples.

Data logging

Logging records pressure over time so you can review a test later or attach the record to a report. The PDR1000 has built-in data logging, and the PDR500 offers it as an option.

Ingress protection

The IP rating describes dust and water resistance. The PDR500 is rated IP66, which covers dust-tight construction and protection from powerful water jets. The Baroli BD Series is rated IP65. Choose a higher rating for wash-down or outdoor use.

Display and cover

A backlit LCD makes readings legible in dim plant rooms. A silicone protective cover, supplied with the PDR500, absorbs knocks on busy sites.

Which digital pressure gauge suits which job?

You can browse the full range in our digital pressure gauge category, and see traditional gauges in our pressure gauges category.

Where digital pressure gauges are used

• Hydraulic systems: checking pump output, relief valve settings and accumulator pre-charge on mobile and fixed plant.
• Pneumatic and compressed air: verifying regulators and checking for leaks and drops in pressure.
• Calibration and testing: checking other gauges and transmitters on a bench or in the field.
• Equipment maintenance: commissioning new equipment and diagnosing faults against the manufacturer’s pressure specification.
• Process monitoring: reading pressure at a point where an operator needs a precise value, not an estimate.

Care, battery life and storage

Most digital gauges run on common batteries and include an automatic power-off to save charge. To get the most from yours:

• Never exceed the stated overpressure limit, and release pressure slowly.
• Keep the gauge clean and dry, and store it in its case when not in use.
• Replace the battery before an important test, not during it.
• Have the gauge calibrated at a regular interval. Many users choose twelve months, and heavy use or critical work may justify a shorter interval.
• Match the wetted material to the media. Check compatibility if you are measuring corrosive fluids.

Common questions

Are digital pressure gauges more accurate than analogue gauges?

Often, yes. Entry-level digital gauges are commonly specified at 0.5% of full scale, while general analogue gauges are often 1.0% to 2.5%. Precision digital models reach 0.1% or better. Always compare the stated accuracy, not just the display type.

Can a digital pressure gauge be used for hydraulics?

Yes, provided the range, overpressure rating and connection suit the circuit. High-range models, such as the PDR250 with ranges up to 700 bar, are designed for these tasks.

How often should a digital pressure gauge be calibrated?

There is no single legal interval for every application. Twelve months is a common starting point, which you can shorten or extend based on usage, environment and the risk of an inaccurate reading.

What does IP66 mean on a gauge?

The first digit, 6, means dust-tight. The second digit, 6, means protection against powerful water jets. It does not mean the gauge can be submerged.

Do I need a gauge with data logging?

Only if you need a record of pressure over time, for example for reports or intermittent faults. For a quick spot check, a gauge with min/max memory is usually enough.

Next steps

Start with the pressure range and connection, then match the accuracy to the job. If you are unsure which model fits your equipment, contact our team with your pressure range, media and thread type and we will help you narrow the choice. For brand background, read our WIKA pressure gauge guide, and for testing and traceability see pressure gauge calibration.