	THERMASGARD® TF43 LM235Z 150mm 51254635594059 −35...+125 °C LM235Z Insertion length: 150 mm 2-wire connection IP54		Quantity: 35,15 € Unit price: 35,15 €

Differential pressure transmitter

Our PREMASREG® and PREMASGARD® differential pressure transmitters are used for the precise measurement of relative, absolute and especially differential pressure.
The measured pressure values are converted into a standard signal of 0-10 V or 4...20 mA.
Piezoresistive measuring elements ensure high accuracy and long-term stability.
Typical applications include the monitoring of ventilation and air conditioning ducts, filter monitoring or differential pressure measurement in technical systems.

Guide and interesting facts about differential pressure transmitters

Pa / bar / inWC
Pressure- Differential pressure and volume flow transducers

PREMASGARD 1125-SD-I

1301-1182-0050-000
±5000Pa
Accuracy: ±50 Pa
4..20mA
IP54
Adjustable irradiated output signal
170,43 €
Pa / bar / inWC
Pressure- Differential pressure and volume flow transducers

PREMASGARD 1111-I

1301-1112-0010-000
±1000 Pa
Accuracy: ±10 Pa
4..20 mA
IP67
Radiated output signal adjustable
172,86 €
Pa / bar / inWC
Pressure- Differential pressure and volume flow transducers

PREMASGARD 1115-I

1301-1112-0050-000
±5000Pa
Accuracy: ±50 Pa
4..20mA
IP67
Radiated output signal adjustable
172,86 €
PREMASGARD 1121-I

13N1-1172-0010-000

172,86 €
Pa / bar / inWC
Pressure- Differential pressure and volume flow transducers

PREMASGARD 1125-I

1301-1172-0050-000
±5000Pa
Accuracy: ± 50 Pa
4..20mA
IP67
Digitized output signal adjustable
172,86 €
Pa / bar / inWC
Pressure- Differential pressure and volume flow transducers

PREMASGARD 2111

1301-1197-0010-000
±11000 Pa
Accuracy: ± 10 Pa
0 -10 V or 4...20 mA (selectable via DIP switch)
IP67
Adjustable linearized output signal
172,86 €
Pa / bar / inWC
Pressure- Differential pressure and volume flow transducers

PREMASGARD 2115

1301-1197-0050-000
±5000 Pa
Accuracy: ±35 Pa
0 -10 V or 4...20 mA (selectable via DIP switch)
IP67
Adjustable scaled output signal
172,86 €
Pa / bar / inWC
Pressure- Differential pressure and volume flow transducers

PREMASGARD 2110

1301-1197-0110-000
±1100 Pa
Accuracy: ± 3 Pa
0 -10 V or 4...20 mA (selectable via DIP switch)
IP67
Adjustable radiated output signal
172,86 €
Pa / bar / inWC
Pressure- Differential pressure and volume flow transducers

PREMASGARD 2121

1301-11A7-0010-000
±1000 Pa
Accuracy: ± 10 Pa
0-10V / 4..20mA
IP67
Adjustable radiated output signal
172,86 €
Pa / bar / inWC
Pressure- Differential pressure and volume flow transducers

PREMASGARD 2125

1301-11A7-0050-000
±5000Pa
Accuracy: ±35 Pa
0-10V / 4..20mA
IP67
Digitized output signal adjustable
172,86 €
Pa / bar / inWC
Pressure- Differential pressure and volume flow transducers

PREMASGARD 2120

1301-11A7-0110-000
±100 Pa
Accuracy: ± 3 Pa
0-10V / 4..20mA
IP67
Radiated output signal adjustable
172,86 €
Pa / bar / inWC
Pressure transmitter

PREMASGARD® SHD-I 6

1301-2112-0550-120
0... 6 bar

4..20mA

G1/2"

suitable for ammonia and Freons
176,50 €
Pa / bar / inWC
Pressure transmitter

PREMASGARD® SHD-I 10

1301-2112-0560-120
0...10 bar

4..20mA

G1/2"

Suitable for ammonia and freones
176,50 €
Pa / bar / inWC
Pressure transmitter

PREMASGARD® SHD-I 16

1301-2112-0570-120
0...16 bar

4..20mA

G1/2"

Suitable for ammonia and Freons
176,50 €
Pa / bar / inWC
Pressure transmitter

PREMASGARD® SHD-U 6

1301-2111-0550-220
0... 6 bar

0-10V

G1/2"

suitable for ammonia and freones
176,50 €
Pa / bar / inWC
Pressure transmitter

PREMASGARD® SHD-U 10

1301-2111-0560-220
0...10 bar

0-10V

G1/2"

suitable for ammonia and freons
176,50 €

Pressure transmitters for air and differential pressure measurement - for ventilation, clean rooms and building automation

Author: S. Becker | Status: 06.03.2026

Differential pressure transmitters - often referred to as differential pressure sensors or Δp sensors - measure the pressure difference between two points and convert this into an electrical output signal.

In a nutshell

A pressure transducer for air measures positive, negative or differential pressure between two points - typically in the range from 25Pa to several kPa. In practice, this means

Reliable filter monitoring
Stable volume flow calculation
Safe pressure zones in clean rooms
Reproducible control variables for BMS and DDC

It is not only the measuring range that is important here - but resolution, temperature compensation and zero-point stability.

Measuring principle & accuracy in the low pressure range Selection guide from practice - Which pressure transmitter is the right one? Installation, pressure acceptance and influence on measurement quality Typical applications in HVAC, clean room and industry

Why differential pressure is crucial in ventilation technology

In HVAC technology, we often work in the low pressure range - 50, 100 or 300 Pa.
That doesn't sound like much, but it is technically demanding.

Typical applications:

Differential pressure across filter (degree of contamination)
Δp measurement on fans
Volume flow rate determination via orifice plates or Pitot tubes
Pressure cascades in clean rooms or laboratories
Monitoring of positive or negative pressure zones

The quality of the differential pressure sensor is crucial, especially for small pressure differences:

Control stability
Energy efficiency
Maintenance intervals
Operational safety

Measuring principle & accuracy in the low pressure range

Our differential pressure transmitters for air work with temperature-compensated piezoresistive sensor elements.

Why is this important?
In the range below 300 Pa, even a small temperature drift can have a noticeable effect on the measured value.

Without compensation:

Incorrect filter messages
Unstable volume flow controls
Unnecessary maintenance work

That's why we pay particular attention during development:

Low temperature drift
Stable zero point position
High resolution with small Δp

Practical selection guide - Which differential pressure transducer is the right one?

We see the same challenges in projects time and time again. So here are our most important selection criteria:

Select the correct measuring range
A measuring range that is too large reduces the resolution.

Example:
If a maximum of 250 Pa occurs, a 0-1000 Pa device is technically possible - but not optimal in terms of measurement technology.

Rule of thumb:
The operating pressure should be in the upper third of the selected measuring range.
Unidirectional or bidirectional?
0...+300 Pa → Filter monitoring
-300...+300 Pa → Pressure zones / clean room
Output signal
0-10 V → Standard in BMS
4-20 mA → interference-free with longer cables
Signal filter
In the case of strongly fluctuating pressure ratios (e.g. fans with frequency converters), an adjustable signal filter is useful in order to obtain a stable output signal.

Calculate volume flow measurement with differential pressure

Many applications use Δp for indirect volume flow measurement - for example in ventilation systems, VAV systems or air ducts.

The basis is:

V = k - √Δp

A square-rooted output that already forms the square root internally can be useful for this. This reduces the computational effort in the DDC and improves the control quality.
This is a real advantage, especially in VAV systems.

Zero point stability & long-term behavior

The zero point is particularly critical for differential pressure sensors in the low pressure range. Even slight mechanical or thermal changes can lead to offset shifts.

That is why our devices have:

Automatic or manual zero point calibration
Temperature-compensated measuring cells
Sturdy housing construction

This ensures reproducible measurement results - even in continuous operation.

Typical applications

Filter monitoring in HVAC systems
Differential pressure measurement in ventilation ducts
Clean room and laboratory monitoring
Fan control
Volume flow measurement
Overpressure or underpressure monitoring in technical rooms
Differential pressure measurement in extraction and process air systems

Air vs. liquids

This category includes differential pressure transmitters for air and non-aggressive gases, as typically used in ventilation systems, clean rooms or HVAC systems.

For applications with water, cooling circuits or hydraulic systems, we recommend our pressure transmitters for liquids in the bar range. A suitable selection for liquids is available in a separate category.

To category Pressure transmitters for liquids

Our differential pressure transmitters and differential pressure sensors for air

Here you will find devices with:

Multi-range switching
0-10 V / 4-20 mA
optional display
IP65/IP67 housing
easy-to-install hose connections
high long-term stability

Select the right pressure transmitter now

We also manufacture individually

Do you have special requirements? As a manufacturer with our own production facilities in Germany, we are also able to produce products outside of the standard range at any time.

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