What is a pressure transmitter and what is it used for
A pressure transmitter is an electronic measuring device that measures pressure and sends it as a standard signal over a distance. While a pressure gauge shows the value only on site, a transmitter enables monitoring, logging and automatic process control: starting pumps, positioning valves, raising alarms and supervising the plant via SCADA. That makes the transmitter the foundation of every automated installation, from water supply and boiler houses to refineries and food production lines.
How a pressure transmitter works
The active element is a piezoresistive silicon sensor, separated from the medium by a metal diaphragm and a carefully selected fill fluid. Pressure deflects the diaphragm, the sensor's electrical resistance changes, and the electronics convert this change into a linear output signal. Smart transmitters with HART protocol allow the range, damping and diagnostics to be set remotely without removing the instrument. Differential pressure transmitters measure the difference between two pressures and are used for flow measurement across orifice plates, filter monitoring and level in closed vessels, while hydrostatic probes measure liquid level from the pressure of the liquid column above the probe.
Transmitters in the Fadip range
The PCE-28 pressure transmitter and AS transmitter are the industrial standard: ranges from 25 mbar to 1000 bar, 4-20 mA or 0-10 V output, 0.2% accuracy (0.16% on request), stainless steel housing and IP68 protection. For network communication there is the PCE-28 Modbus, with ranges up to 1380 bar.
Smart pressure transmitters PCE-28.Smart, APCE-2000PD with a gold-plated diaphragm and APC-2000ALW with a local display offer HART protocol and accuracy from 0.1% to 0.075% (down to 0.04% on request).
Differential pressure transmitters APR-2000ALW and PRE-28.Smart measure differential pressures from 1 mbar to 70 bar, while the APM-2 calculates differential pressure from two absolute pressure sensors.
Level probes APC-2000ALW/L, SGE-25 and SGE-16 and SGE-25.Smart measure level from 0.5 to 500 m of water column in tanks, boreholes and wastewater.
How to choose a pressure transmitter
Six parameters need to be defined. Pressure type: gauge, absolute, vacuum or differential. The measuring range should cover the working pressure with a margin for surges, and on smart transmitters the range can be turned down later. The output signal depends on the control system: 4-20 mA is the most resistant to interference and long cable runs, HART adds diagnostics, and Modbus RTU allows several devices on one line.
The medium and temperature determine the diaphragm material and whether a diaphragm seal is needed, and for viscous and sticky media a flush diaphragm is used. The process connection (G1/2", 1/2" NPT, M20x1.5, flange) must match the measuring point. For hazardous areas, ATEX or IECEx certification and the appropriate type of protection are required.
Technical specifications
The transmitters in our range cover 1 mbar to 1380 bar, with 4-20 mA, 4-20 mA + HART, 0-10 V and Modbus RTU outputs. Accuracy ranges from 0.2% on standard models to 0.075% on smart models, and 0.04% on request. Housings are 304/316 stainless steel or aluminium, with IP65 to IP68 protection. Ambient temperature is -40 to +85 °C and medium temperature up to 120 °C (150 °C for the APM-2), or higher with diaphragm seals. Process connections are 1/2" NPT, M20x1.5, G1/2", flush diaphragm G1/2" and G1", or diaphragm seal.
Pressure and level transmitter applications
In water supply and sewerage, transmitters and level probes control pumping stations, booster sets and boreholes. Power generation and district heating use smart transmitters for steam, feedwater and differential flow measurement. The chemical, petrochemical and oil industries require ATEX versions with diaphragm seals, while the food and pharmaceutical industries use transmitters with flush diaphragms and hygienic connections. In HVAC systems, differential transmitters monitor filter condition and air flow, and in hydraulics and mechanical engineering transmitters up to 1000 bar monitor presses and power units.
Why source transmitters through Fadip
Fadip is an authorised distributor of measurement and control equipment and also a pressure gauge manufacturer, so you can source the whole measuring point in one place: transmitter, valve manifold or diaphragm seal, a pressure gauge for local reading and a digital indicator. Our technical team helps with the choice of range, signal and connection, and our accredited laboratory calibrates electromechanical pressure instruments with analogue and digital display in the range from -1 to 1000 bar.
Alongside transmitters we offer valves and diaphragm seals, digital indicators, level switches and pressure gauges.
For a quotation, send us the pressure type and range, medium, temperature, output signal, process connection and hazardous area classification. Our technical team will recommend a suitable transmitter within 24 hours. Contact us.
