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Low-pressure gauges for measuring small positive, negative and differential pressures

Low-pressure gauges measure small positive pressures, negative pressures and differential pressures in air and other gases.
They are used wherever even slight pressure changes must be displayed or monitored reliably.
Typical applications include ventilation and air-conditioning systems, cleanrooms, filter systems, burners, laboratory equipment and gas supply systems.
Depending on their design, low-pressure gauges operate mechanically or electronically and measure gauge pressure, vacuum or differential pressure.
The following sections describe common types, applications and important selection criteria.

Types of low-pressure gauges

Diaphragm pressure gauges

Diaphragm pressure gauges measure low pressures through the deformation of an elastic diaphragm.
They are particularly suitable for gaseous media and small positive or negative pressures.
The low-friction measuring mechanism enables sensitive measurement and clear indication of small pressure changes.

Capsule pressure gauges

Capsule pressure gauges use a measuring element consisting of two diaphragms joined together to form a capsule.
They are suitable for very low pressures and dry, non-aggressive gases.
Typical applications include ventilation systems, gas supply equipment and laboratory installations.

Differential pressure gauges

Differential pressure gauges measure the pressure difference between two measuring points.
They are commonly used to monitor filters, air ducts, cleanrooms and fans.
When selecting a differential pressure gauge, the permissible static pressure at both pressure connections must also be considered.

Digital low-pressure gauges

Digital low-pressure gauges display small pressure values with high resolution.
Depending on the model, additional functions may include unit selection, zero adjustment, minimum and maximum value storage or data logging.
They are frequently used for maintenance, commissioning, adjustment and testing tasks.

Applications of low-pressure gauges

Ventilation and air-conditioning systems

In ventilation systems, low-pressure gauges measure pressure in air ducts and upstream or downstream of filters and fans.
Changes in pressure can indicate contaminated filters, altered airflow conditions or system malfunctions.

Cleanroom technology

In cleanrooms, differential pressure gauges monitor the pressure conditions between individual rooms or controlled areas.
This helps maintain the required airflow between zones with different cleanliness classifications.

Gas and burner systems

Low-pressure gauges monitor supply pressures, nozzle pressures and differential pressures in gas lines and burner systems.
The measuring range, process connection and wetted materials must be suitable for the gas being measured.

Filter monitoring

The pressure drop across a filter increases as the level of contamination rises.
Differential pressure gauges indicate when cleaning or filter replacement is required and therefore support condition-based maintenance.

Laboratories and test facilities

In laboratories and test facilities, low-pressure gauges are used to monitor small pressure changes and airflow conditions.
Digital low-pressure gauges provide precise readings and may also allow measured values to be documented.

Advantages of low-pressure gauges

• Sensitive measurement of small pressure changes
• Suitable for positive pressure, vacuum and differential pressure
• Designed primarily for air and other gaseous media
• Mechanical and digital versions available
• Direct monitoring of filters and ventilation systems
• Portable and permanently installed models available

Limitations of low-pressure gauges

• Excessive pressure can damage sensitive measuring elements.
• Moisture, particles or contaminated media can impair measurement reliability.
• The specified mounting position and zero point must be observed.
• Temperature changes can affect measurement accuracy.
• Digital low-pressure gauges require a suitable power supply.

Important selection criteria for low-pressure gauges

Measuring range

The measuring range must correspond to the expected pressure values.
An unnecessarily wide measuring range reduces resolution and makes small pressure changes more difficult to identify.

Type of pressure

It must be determined whether positive pressure, vacuum or differential pressure is to be measured.
Differential pressure gauges require two suitable pressure connections.

Measuring medium

Many low-pressure gauges are intended for dry air and non-aggressive gases.
For moist, contaminated or aggressive media, suitable materials, filters or other protective measures must be selected.

Accuracy and resolution

The required accuracy depends on the intended application.
Testing, adjustment and laboratory tasks generally require greater accuracy and finer resolution than simple operating checks.

Overpressure resistance

Even in applications with very small measuring ranges, substantially higher pressures may occur temporarily.
The low-pressure gauge should therefore provide sufficient overpressure resistance or be protected by an appropriate safety device.

Process connection and installation

The connection type, hose diameter and mounting position must match the measuring point.
Stable installation with minimal vibration improves readability and measurement reliability.

Summary

Low-pressure gauges measure small positive pressures, negative pressures and differential pressures in air and other gases.
They are mainly used in ventilation and air-conditioning systems, cleanrooms, gas and burner equipment, filter monitoring and laboratories.
Common designs include diaphragm pressure gauges, capsule pressure gauges, differential pressure gauges and digital low-pressure gauges.
Important selection criteria include the measuring range, pressure type, measuring medium, accuracy, overpressure resistance and process connection.
A suitable low-pressure gauge enables reliable monitoring of small pressure changes and supports safe and efficient system operation.

Low-pressure gauges are available from various manufacturers and suppliers. Comprehensive information about manufacturers and suppliers of low-pressure gauges from around the world can be found on Exportpages.