Pressure measuring instruments and pressure gauges – find manufacturers and suppliers

Pressure measuring instruments measure and monitor the pressure of gases, liquids and vapours in technical systems, machines and processes.

They display the measured pressure directly or provide measurement values for testing, documentation and monitoring tasks.
Depending on the design, pressure measuring instruments measure gauge pressure, vacuum, absolute pressure or the pressure difference between two measuring points.
Typical areas of application include hydraulics, pneumatics, the process industry, energy supply, water technology, building services, laboratories and mechanical engineering.
The available range includes mechanical pressure gauges, digital pressure measuring instruments, differential pressure measuring instruments, vacuum gauges and portable test instruments.
The following overview describes typical designs, applications, advantages, limitations and important selection criteria for pressure measuring instruments.

Types of pressure measuring instruments

Mechanical pressure measuring instruments

Mechanical pressure measuring instruments detect pressure through the deformation of an elastic measuring element.
The movement is transmitted to a pointer mechanism and displayed on a scale.
They require no external power supply and allow direct pressure monitoring at the installation point.
Depending on the pressure range, Bourdon tubes, diaphragms or capsule elements are used as measuring elements.

Bourdon tube pressure gauges

Bourdon tube pressure gauges use a curved tube that deforms slightly under pressure.
This movement is transmitted mechanically to a pointer.
Bourdon tube pressure gauges are suitable for numerous gaseous and liquid media as well as for medium and high pressures.
They are frequently used in hydraulic systems, compressors, pumps and industrial supply systems.

Diaphragm pressure measuring instruments

Diaphragm pressure measuring instruments detect pressure through the deformation of an elastic diaphragm.
They are particularly suitable for low pressures and for viscous, contaminated or crystallising media.
A flush diaphragm can reduce deposits and dead spaces at the process connection.
The material and coating of the diaphragm must be compatible with the measuring medium.

Capsule pressure gauges

Capsule pressure gauges use a measuring element consisting of two diaphragms joined together.
They are intended for very low pressures and gaseous media.
Typical applications include ventilation systems, gas supply, laboratory equipment and the monitoring of small pressure differences.
Excessive overpressure can damage the sensitive measuring element.

Digital pressure measuring instruments

Digital pressure measuring instruments convert the measured pressure into an electrical signal and display the value on a screen.
They often provide better reading accuracy than mechanical pointer instruments.
Additional functions may include minimum and maximum value storage, unit switching, data logging and limit monitoring.
Depending on the design, power is supplied by batteries, rechargeable batteries or an external power source.

Differential pressure measuring instruments

Differential pressure measuring instruments detect the pressure difference between two measuring points.
They are used for monitoring filters, pumps, ventilation systems, cleanrooms and closed vessels, among other applications.
Flow rate or fill level can also be derived from the pressure difference.
The permissible static pressure at both connections must be taken into account during selection.

Absolute pressure measuring instruments

Absolute pressure measuring instruments use a complete vacuum as a fixed reference point.
Their reading is therefore not directly affected by fluctuations in atmospheric pressure.
They are used in vacuum technology, laboratories, altitude measurements and certain process systems, for example.
The measuring range must suit the expected absolute pressure.

Vacuum gauges

Vacuum gauges measure pressures below atmospheric pressure.
They are used with vacuum pumps, suction systems, packaging machines, laboratory equipment and in process engineering.
Depending on the measuring task, they may display vacuum relative to atmospheric pressure or absolute pressure.
Special vacuum measuring principles are required for very low pressures.

Compound pressure gauges

Compound pressure gauges have a measuring range for both vacuum and positive pressure.
They are suitable for systems in which both pressure conditions can occur.
Typical applications include pump systems, suction and pressure lines as well as certain refrigeration and process systems.
The scale must fully cover the required vacuum and positive-pressure range.

Precision and reference pressure measuring instruments

Precision pressure measuring instruments are used for testing, comparison measurements and calibration tasks.
They offer higher measuring accuracy and documented measurement uncertainty.
Digital reference instruments can store measurement values or transfer them to testing software.
Regular calibration is required to maintain the specified accuracy.

Portable pressure measuring instruments

Portable pressure measuring instruments are suitable for maintenance, commissioning, troubleshooting and mobile testing.
They can be connected directly to a measuring point or used with hoses and test connections.
Robust housings and an independent power supply facilitate on-site use.
The measuring range, connection and degree of protection must suit the respective system.

Applications of pressure measuring instruments

Hydraulics

In hydraulic systems, pressure measuring instruments monitor pumps, cylinders, accumulators and control circuits.
Deviating pressure values can indicate leaks, overload, wear or incorrectly adjusted valves.
Damped or liquid-filled instruments may be required where pressure pulsations occur.

Pneumatics and compressed-air technology

Pressure measuring instruments monitor the operating pressure in compressors, compressed-air receivers, air-service units and pneumatic control systems.
They assist in adjusting pressure regulators and detecting pressure losses.
The measuring range should display the normal operating pressure clearly and provide sufficient overload reserves.

Process industry

In chemical, petrochemical and process-engineering plants, pressure measuring instruments monitor vessels, pipelines and reactors.
Media compatibility, temperature, process connection and plant safety are particularly important.
For aggressive or hot media, diaphragm seals can separate the measuring instrument from the process.

Water and wastewater technology

Pressure measuring instruments are used on pumps, filters, pipeline networks and treatment plants.
They indicate delivery pressure, line pressure and pressure losses.
Differential pressure measurements can be used to monitor filter contamination or pump performance.

Heating, ventilation and air-conditioning technology

In heating systems, pressure measuring instruments monitor system and pump pressure.
In ventilation systems, low pressures and differential pressures are measured across filters, fans and air ducts.
Sensitive diaphragm or capsule pressure gauges are suitable for low air pressures.

Food and pharmaceutical industries

Hygienic pressure measuring instruments monitor production, cleaning and sterilisation processes.
Flush process connections facilitate cleaning and reduce deposits.
Materials, seals and design must comply with hygienic and regulatory requirements.

Mechanical and plant engineering

Pressure measuring instruments are integrated into machines and systems for local indication, function monitoring and commissioning.
They enable operating personnel to assess the operating condition quickly.
Dimensions, installation position and connection must suit the machine design.

Laboratories, testing and calibration

In laboratories and testing facilities, precise pressure measuring instruments are used for experiments, comparison measurements and calibration.
High resolution, stable measurement values and traceable calibration are essential.
Digital instruments can document test values and process them electronically.

Advantages of pressure measuring instruments

• Direct monitoring of operating and process pressures
• Measurement of gases, liquids and vapours
• Versions available for gauge pressure, vacuum, absolute pressure and differential pressure
• Mechanical instruments available without an external power supply
• Digital instruments available with high resolution and additional functions
• Early detection of faults and pressure losses
• Support for maintenance, commissioning and quality assurance
• Wide range of measuring ranges and process connections
• Versions available for aggressive, viscous and hygienic media
• Stationary and portable instruments available

Limitations of pressure measuring instruments

• An unsuitable measuring range can reduce readability and accuracy.
• Overpressure can permanently damage the measuring element.
• Pressure shocks and pulsations can cause increased wear.
• Vibrations make pointer instruments more difficult to read.
• Incompatible media can attack measuring elements, seals and connections.
• High or low temperatures can influence the measurement result.
• Digital instruments require a power supply.
• Mechanical instruments do not provide data transmission without additional equipment.
• Deposits or blockages can impair pressure transmission.
• Pressure measuring instruments must be inspected regularly and calibrated where necessary.
• Incorrect installation positions can cause additional measurement deviations.
• Damaged instruments must not continue to be used in safety-relevant applications.

Important selection criteria for pressure measuring instruments

Type of pressure

It must first be determined whether gauge pressure, absolute pressure, vacuum or differential pressure is to be measured.
Gauge pressure is referenced to atmospheric pressure, whereas absolute pressure is referenced to a complete vacuum.
Differential pressure describes the difference between two measuring points.

Measuring range

The measuring range must cover the expected operating pressure and possible pressure peaks.
The normal operating pressure should lie within an easily readable section of the scale.
An unnecessarily large measuring range reduces resolution and makes small pressure changes more difficult to detect.

Measuring accuracy

The required accuracy depends on the application.
For basic operating checks, a lower accuracy class is often sufficient than for testing and calibration tasks.
With digital instruments, resolution, temperature error and long-term stability must also be considered in addition to accuracy.

Measuring medium

All wetted parts must be compatible with the gas, liquid or vapour being measured.
Corrosive, viscous, crystallising or contaminated media may require special materials or a flush diaphragm.
Additional protective measures are necessary for hazardous media.

Process and ambient temperature

High media temperatures can affect the measuring element and the display.
Cooling elements, capillary lines or diaphragm seals can thermally isolate the pressure measuring instrument from the process.
The permissible ambient temperature of the housing and electronics must also be observed.

Process connection

Threaded connections, flanges, clamp connections and the connection position must match the available measuring point.
Hygienic systems frequently use easy-to-clean flush connections.
Adapters must not impair pressure resistance, leak tightness or media compatibility.

Measuring element

Bourdon tubes are suitable for numerous medium and high pressures.
Diaphragms and capsule elements are particularly suitable for low pressures, differential pressures or demanding media.
Electronic measuring cells enable digital displays and additional evaluation functions.

Display type

Analogue pointer displays can be read directly without a power supply.
Digital displays provide precise numerical readings and frequently offer selectable pressure units.
Size, illumination, viewing angle and reading distance should suit the installation location.

Overpressure resistance

Pressure peaks can significantly exceed the normal operating pressure.
The instrument must have sufficient overpressure resistance or be protected by damping elements, pressure relief valves or overload protection.
For differential pressure measuring instruments, the maximum static pressure must also be considered.

Pulsations and vibrations

Pumps, compressors and rapidly switching valves can cause strong pressure fluctuations.
Restrictors, damping elements or liquid-filled housings stabilise the indication and protect the movement.
However, damping must not delay necessary rapid pressure changes excessively.

Housing and degree of protection

The housing protects the display and measuring element against dust, moisture and mechanical stress.
Stainless-steel housings are suitable for corrosive and demanding environments.
A suitable degree of protection is required for outdoor installation or cleaning with water.

Mounting type and installation position

Pressure measuring instruments can be mounted directly on the process, in a control panel or via a measuring line.
The intended installation position must comply with the manufacturer’s instructions.
A separate mounting bracket may be advisable for heavy instruments or strong vibrations.

Additional functions

Digital instruments can store minimum and maximum values, peak values or pressure trends over time.
Other functions include unit switching, limit indication, data transmission and leakage testing.
The required functions should be selected according to the actual measuring task.

Calibration and traceability

For quality-relevant measurements, accuracy must be checked regularly.
Calibration certificates document the deviation from a reference instrument.
The calibration interval and required traceability depend on the application, operating conditions and internal specifications.

Summary

Pressure measuring instruments measure and monitor the pressure of gases, liquids and vapours in machines, systems and technical processes.
Available types include mechanical pressure gauges, digital pressure measuring instruments, differential pressure measuring instruments, absolute pressure measuring instruments, vacuum gauges and precision instruments.
Typical applications can be found in hydraulics, pneumatics, the process industry, water technology, building services, mechanical engineering and laboratories.
Important selection criteria include the type of pressure, measuring range, accuracy, medium, temperature, process connection, measuring element and overpressure resistance.
A suitable pressure measuring instrument enables reliable operating control, supports troubleshooting and contributes to safe and efficient process management.

Pressure measuring instruments are available from various manufacturers and suppliers. Comprehensive information about manufacturers and suppliers of pressure measuring instruments from around the world can be found on Exportpages.