Differential pressure transmitters are essential components in measurement and control technology – wherever the pressure difference between two points needs to be monitored. Unlike relative or absolute pressure sensors, they specifically measure the differential pressure, for example before and after a filter, in ventilation ducts or between two room zones.
Our differential pressure sensors are used in HVAC systems, clean rooms, industrial plants, and building automation. They provide precise measured values and standardized output signals such as 0–10 V or 4–20 mA – ideal for control, regulation, or monitoring systems.
This guide provides you with everything you need to know about function, areas of application, types, and accessories – explained in a compact and practical manner.
What is a differential pressure transmitter?
A differential pressure transmitter is a measuring device for precisely detecting the pressure difference between two points in a system. Unlike relative pressure sensors, which refer to the ambient pressure, a differential pressure sensor measures only the difference – regardless of external influences. It has two separate pressure connections for this purpose: one for the higher pressure (“+”) and one for the lower (“–”) measuring point.
The measurement result is converted into a standardized electrical output signal – e.g., 0–10 V or 4–20 mA – and can be fed directly into control systems, regulation systems, or monitoring systems. Differential pressure transmitters are therefore essential when it comes to monitoring air flows, filter conditions, volume flows, or zone conditions in HVAC, industrial, or clean room applications.
How does differential pressure measurement work?
Differential pressure measurement records the pressure difference between two defined points – for example, before and after an air filter. A differential pressure transmitter has two separate connection ports for this purpose: one for the higher pressure (“+”) and one for the lower pressure (“–”).
Inside the device is a highly sensitive piezoresistive sensor element that reacts to this pressure difference. If the membrane deforms under the influence of pressure, the electrical resistance in the sensor changes – this physical effect is evaluated and converted into an analog output signal (e.g., 0–10 V or 4–20 mA). This signal can be integrated into HVAC systems, industrial plants, or control centers and is used for the continuous monitoring of air flows, volume flows, or pressure zones.
Many of our models also offer DIP switches for configuration, so that measuring ranges and signal types can be set directly on site – without the need for software.
Typical applications for differential pressure sensors?
Differential pressure sensors are used wherever pressure conditions in gases or air flows need to be monitored. They are particularly indispensable in HVAC technology, building automation, clean room technology, and industrial processes.
A common field of application is filter monitoring: The sensor measures the pressure before and after an air filter. If the differential pressure rises, this signals a blockage – a maintenance indicator. Differential pressure transmitters also ensure precise and reliable measurement results in volume flow measurement, pressure zone control, duct networks, and room pressure monitoring (e.g., between air locks and clean rooms).
Thanks to standardized output signals (0–10 V or 4–20 mA), the devices can be easily integrated into existing systems – from compact controllers to building management systems.
Types of differential pressure transmitters
Differential pressure transmitters are available in different types and device series – depending on the area of application, installation environment, and system requirements. Compact versions are ideal for standard applications in building technology, while more robust models with IP65 housing are specially designed for technical control centers, industrial plants, or harsh environments.
- Pressure transmitter housing, high: These pressure transmitters are designed for precise differential pressure measurements and are available in several housing variants, depending on space requirements and cable routing.
| | | | Features: - Different housing orientations (top/bottom) for flexible installation
- Optional LCD for local pressure display
- Configurable via DIP switch
- Ideal for HVAC, clean rooms, building management systems
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- High pressure transmitter 0–10 V / 4–20 mA: This product group offers versatile transmitters with selectable signal outputs and optional display. They are easy to install and configure – even on site.
| | | | Features: - Precise differential pressure measurement
- Robust housing for continuous operation
- LCD display depending on version
- Outputs optionally with 0–10 V or 4–20 mA
- Ideal for air ducts, volume flow measurement, filter monitoring
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- Differential pressure switch: These devices are used for simple, mechanical monitoring of pressure differences. They trigger a switching contact as soon as a specified pressure value is exceeded or fallen below – without any analog output signal.
| | | | - Areas of application: Filter monitoring, air flow, simple HVAC applications
- Advantages: Power-free operation, simple installation, clearly defined switching point
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Installation and connection of differential pressure transmitters
For precise measurement, it is crucial that the differential pressure transmitter is installed and connected correctly. The device has two pressure connections: “+” for the side with higher pressure and “–” for the side with lower pressure. These must be connected cleanly, tightly, and securely—ideally with a suitable connection set including hoses and probes.
They can be mounted on walls, in technical centers, or directly on ventilation ducts. Make sure that the connections are voltage-free and avoid kinks. For outdoor applications, additional sun protection is recommended to minimize the influence of temperature on the measurement.
Thanks to DIP switches or optional displays, many devices can be configured and read out directly on site – without external software.
Performance and service life: What influences sensor quality?
Our differential pressure transmitters are designed for long-term stability and reliable continuous operation. However, the environment can influence sensor performance: contamination, dust, high humidity, or aggressive gases have a negative effect on accuracy.
Regular visual inspections, professional installation, and the use of accessories such as mounting brackets, filter sets, or protective housings can significantly extend the service life. Optional calibration at intervals can also help to detect deviations at an early stage and ensure consistently accurate measurement results.
What should you look for when selecting a differential pressure transmitter?
The selection of the right differential pressure transmitter depends on the specific application and the technical conditions. Important criteria are:
- Measuring range: Select a range that matches the expected pressure difference. Measuring ranges that are too small or too large will lead to inaccurate results.
- Signal type: Depending on system compatibility, choose between 0–10 V (voltage-based, ideal for short distances) and 4–20 mA (current-based, interference-free over longer cables).
- Housing design: For use in demanding environments, models with IP65 housing or optional sun protection are recommended.
- With or without display: An integrated display allows direct on-site display and facilitates maintenance and commissioning.
- Configurability: Many devices have DIP switches that allow the measuring range and output signal to be adjusted without tools.
- Media compatibility: Pay attention to the suitability for the medium – our sensors are designed for air and non-aggressive gases.
A precisely selected differential pressure sensor ensures reliable measurement results, high system compatibility, and long-term stable process conditions.
Where can I find all the technical data for the pressure transmitters?
All technical data and relevant information about our pressure transmitters can be found directly on the respective product pages or in the corresponding download area. There you can download data sheets, operating instructions, and declarations of conformity—with detailed specifications, installation instructions, and important information for safe use.
What accessories can I use with the differential pressure transmitters?
The right accessories ensure safe installation and long-term reliable operation of your differential pressure transmitter. Depending on the location of use, the following components are available:
- Mounting brackets: For easy and stable mounting on walls, control cabinets, or ventilation ducts—ideal for technical rooms or compact system areas.
- Connection sets: Consisting of hoses, probes, and seals, they enable standard-compliant connection to air ducts or pressure measuring points. They ensure measurement quality, prevent leaks, and simplify commissioning.
- Sun Protection: For outdoor applications, a sunshield protects the device from direct UV radiation and temperature peaks, ensuring consistent measurement results.
All accessories are precisely matched to our differential pressure transmitters and support efficient installation, long service life, and high measurement accuracy
Frequently asked questions about differential pressure transmitters
What is the difference between differential pressure, relative pressure, and absolute pressure?
Differential pressure measures the pressure difference between two points. Relative pressure refers to the ambient pressure, while absolute pressure indicates the distance to the vacuum. Differential pressure sensors are ideal for applications such as filter monitoring or air flow control.
How do I install a differential pressure transmitter correctly?
The connection is made via two separate pressure inputs: “+” for higher pressure, “–” for lower pressure. Use suitable connection sets, ensure that the cables are laid tightly and without tension, and avoid kinks in the hoses.
How accurate are differential pressure sensors?
High-quality devices offer accuracies of ±1 to ±2% of the measured value. The actual precision depends on the model, measuring range, and ambient conditions. Our sensors are optimized for continuous, stable measurements in HVAC and industrial applications.
Do differential pressure transmitters require a power supply?
Yes, all active models require an external power supply – usually 24 V DC.
You can find the exact specifications in the respective data sheet.
What are 0–10 V and 4–20 mA output signals suitable for?
0–10 V is ideal for short cable lengths and systems with voltage input. 4–20 mA offers higher interference immunity over long distances and is often used in industrial environments.
What is the service life of a differential pressure sensor?
When used properly, our sensors have a service life of many years. Protective measures such as filter caps, regular calibration, and proper installation further extend the service life.
