Digital Display Vacuum Transmitter 4-20ma Diffusion Silicon Pressure Sensor

The diffused silicon pressure transmitter is a high-precision pressure measurement instrument based on the piezoresistive effect of semiconductors. It measures pressure by detecting the resistance change caused by the deformation of a silicon diaphragm and outputs a standard electrical signal after signal processing.

Piezoresistive effect: When pressure is applied to the diffused silicon diaphragm, the lattice structure of the silicon crystal changes, resulting in a change in the strain resistance value on the diaphragm. The resistance change is converted into a voltage signal through a Wheatstone bridge, and then undergoes amplification, temperature compensation, and linearization processing, ultimately outputting standard signals such as 4-20mA and 0-5V.

Structural Design: Usually, a 316L stainless steel isolation diaphragm is adopted, which is in contact with the measured medium through silicone oil or directly, ensuring corrosion resistance and long-term stability.

1. High Precision and Stability
   • Linearity can reach ±0.2% FS, repeatability ±0.1% FS, and long-term stability ±0.02% FS/year.
   • Intelligent temperature compensation technology effectively suppresses zero drift (±0.01% FS/℃) and sensitivity drift (±0.02% FS/℃).
2. Wide Temperature Range and Overload Capacity
   • Operating temperature range is typically -40℃ to 85℃, with some models supporting higher temperatures (e.g., 350℃).
   • Overload capacity up to 150% FS, and some models can withstand 2 times the range pressure.
3. Protection and Explosion-proof Performance
   • Enclosure protection grade IP67/IP65, waterproof and dustproof.
   • Explosion-proof certifications include intrinsically safe ExiaIICT5 and flameproof ExdIIBT4, suitable for hazardous environments.
4. Flexible Interfaces and Compatibility
   • Pressure interfaces are available in thread types (e.g., G1/2, NPT), flange (DN25/DN50), etc.; electrical interfaces include HART, aviation plugs, or direct leads.
   • Supports output protocols such as HART, 4-20mA, 0-5V, etc., and can be seamlessly integrated with PLC and DCS systems.

1. Industrial Process Control
   • Petrochemical: Monitoring pressure in reaction vessels, calculating flow in pipelines.
   • Power and Energy: Controlling pressure in boiler steam drums, steam turbines.
   • Metallurgy and Steel: Optimizing pressure in blast furnaces and converters.
2. Environmental Protection and Municipal Services
   • Sewage Treatment: Regulating air pressure in aeration tanks, measuring liquid levels.
   • Urban Water Supply: Monitoring pressure in water distribution networks, managing pumping stations.
3. Special Environments
   • High Temperature and High Pressure Scenarios: Geothermal wellheads (350°C), high-pressure oil and gas wells.
   • Strong Vibration Environments: Offshore oil drilling platforms, steel rolling equipment (requiring Hirschmann interface anti-vibration design).

1. Key Points for Selection
   • Range Selection: It is recommended that the working pressure be 60% - 80% of the range to avoid long-term overload.
   • Medium Compatibility: For corrosive media, 316L stainless steel or chemical seal design should be selected.
   • Explosion-proof Certification: In hazardous areas, confirm the Exia or Exd grade.
2. Installation Guidelines
   • Location Selection: Keep away from vibration sources, avoid direct sunlight and sudden temperature changes.
   • Connection Method: Flange is suitable for high pressure, while thread is suitable for low pressure. Ensure no leakage in the seal.
   • Pressure Conduit Layout: For liquid media, the pressure conduit should be inclined upwards (≥1/12 slope), and for gas media, it should be inclined downwards to prevent accumulation of gas and liquid.
3. Maintenance Notes
   • Regularly clean the pressure interface to prevent blockage.
   • Calibrate once a year to ensure accuracy.
   • In high-temperature environments, install a condensate bend to prevent silicone oil vaporization.