PRESSURE TRANSMITTERS

Trafag pressure transmitters are high-quality pressure measurement devices suited to most requirements in very many of the harshest application areas. Apart from mature amplifier electronics ─ in the very latest products, equipped with ASIC ─ the associated pressure sensor is also of focal importance. For this reason, Trafag develops and manufactures each and every sensor in-house and is therefore able to look back over longstanding design and field experience in this sector.

All Trafag`s pressure sensors are based on the Wheatstone (resistance) bridge. At a change in pressure (deformation of the membrane), the resistance alters proportionally. This results in a change in current at the bridge.
Trafag Pressure Sensors
Trafag pressure transmitters function on the following principles:
Thin-film-on-steel
By means of complex coating processes under high vacuum, a thin layer of film, only a few micrometers thick, is superimposed on a stainless steel membrane. The pressure sensor is then welded together with a pressure connection to form an assembly highly compatible with sample media.
Advantages
- Completely weld-sealed sensor system made of stainless steel
- No additional materials (e.g. O-rings) which could limit compatibility with certain sample media
- Withstands very high overpressures of at least twice nominal pressure (burst pressure: approx. 3...10-fold of nominal pressure)
- For gauge pressure ranges of 0....200 mbar up to 0....2000 bar
- Excellent long-term stability (zero point less than 0.1% FS after 1000 h at 120°C)
- High temperature-resistance
- No backfilling of liquid necessary
>>Download data sheet thin-film-on-steel pressure sensors H72205
Thick-film-on-ceramic
A Wheatstone bridge is superimposed onto a ceramic membrane by means of a screen printing process (thick film), and then fired.
Advantages
- Resistant to aggressive media
- For gauge and absolute pressure ranges from -1 to 250 bar
- Inexpensive pressure sensor system for straightforward applications
- No backfilling of liquid necessary
>> Download data sheet thick-film-on-ceramic pressure sensors H72233

Piezo-resistive systems:
In the piezo-resistive process, pressure is transferred indirectly to the measurement membrane via a liquid, normally silicone oil. Due to the temperature dependence of this transfer liquid, the procedure is influenced by changes in temperature. Temperature-compensation is therefore essential.
Advantages
- Inexpensive pressure measurement sensor
- Large degree of freedom in arrangement of pressure connections (e.g. front-flush and submersible diaphragms)
- Low-level pressure ranges up to 100mbar (absolute or gauge pressure measurements)