Capacitive Pressure Transmitter for High-Precision Process Measurement
1. Why You Need It
When process control depends on precise, stable pressure measurement — batching, dosing, custody-sensitive process loops — a capacitive transmitter is the proven choice. The capacitive sensing principle offers excellent accuracy, long-term stability and low drift compared to simpler strain-gauge sensors. With IP67/IP68 protection and multiple outputs including RS485, this transmitter delivers the precision and reliability that demanding process applications require.
2. Working Principle
The transmitter uses a capacitive sensor: two plates form a capacitor whose capacitance changes as pressure deflects a diaphragm, altering the gap between the plates. This capacitance change is converted to a highly linear, stable output signal. Because capacitance measurement is inherently stable and low-drift, the transmitter maintains its accuracy over time, and the electronics provide 4-20 mA, 0-5 V, 0-10 V and RS485 outputs for flexible integration.
3. Key Advantages
- Capacitive sensing principle
- High precision and stability
- IP67 / IP68 protection
- 4-20 mA / 0-5 V / 0-10 V / RS485
- 12-36 V DC power supply
- M12 electrical connection
- 0 to 1000 psi range
- Low long-term drift
- Suitable for process measurement
- Robust industrial design
Common Pain Points & Solutions
| Problem | Conventional Issue | Our Solution | Result |
|---|
| Precision process control | Strain-gauge sensors drift | Capacitive sensor | High precision, low drift |
| Long-term stability | Sensors need frequent calibration | Stable capacitive principle | Fewer recalibrations |
| Harsh / wet environment | Standard sensors fail | IP67 / IP68 protection | Reliable in harsh conditions |
| Multi-output integration | Single-output limits | 4-20mA / V / RS485 | Fits any control system |
Application Cases
Industry: Process
Application: Batching / dosing pressure
Medium: Process liquid
Pressure Range: 0-1.0 MPa
Operating Temperature: 10-80 °C
Installation Environment: Process area
Customer Challenge: Precise dosing control
Previous Problem: Drift caused batch error
Solution: Capacitive transmitter, 4-20 mA
Installation Location: Batch vessel
Result: Consistent batch accuracy
Industry: Chemical
Application: Reactor pressure monitoring
Medium: Chemical
Pressure Range: 0-2.5 MPa
Operating Temperature: 10-120 °C
Installation Environment: Chemical plant
Customer Challenge: Stable pressure data
Previous Problem: Sensor drift
Solution: High-precision capacitive transmitter
Installation Location: Reactor
Result: Stable, accurate control
Industry: Water
Application: Pump station pressure
Medium: Water
Pressure Range: 0-1.6 MPa
Operating Temperature: 5-40 °C
Installation Environment: Washdown area
Customer Challenge: Reliable in wet conditions
Previous Problem: Ingress failure
Solution: IP67/IP68 transmitter, RS485
Installation Location: Pump discharge
Result: Reliable, networked monitoring
Industry: HVAC
Application: Chiller / refrigerant pressure
Medium: Refrigerant
Pressure Range: 0-4.0 MPa
Operating Temperature: -20 to 60 °C
Installation Environment: Mechanical room
Customer Challenge: Accurate refrigerant control
Previous Problem: Imprecise sensor
Solution: Capacitive transmitter, 0-5 V
Installation Location: Chiller
Result: Accurate HVAC control
Technical Specifications
| Specification | Value |
|---|
| Sensor Element | Capacitive |
| Measurement Range | 0 to 1000 psi |
| Output | 4-20 mA / 0-5 V / 0-10 V / RS485 |
| Power Supply | 12-36 V DC |
| Protection | IP67 / IP68 |
| Electrical Connection | M12 |
| Output Type | Analog (+ digital RS485) |
| Application | Process pressure measurement |
FAQ
Q: What is a capacitive pressure transmitter?
A capacitive pressure transmitter measures pressure using a capacitor whose capacitance changes as a diaphragm deflects under pressure. The capacitance change is converted into a linear output signal. The capacitive principle offers high accuracy, excellent stability and low drift, making it the preferred technology for precision process measurement.
Q: Why is capacitive better than strain-gauge?
Capacitive sensors are generally more stable and linear than strain-gauge sensors, with lower long-term drift and better performance at low pressures. This means fewer recalibrations and more consistent measurement over time. Capacitive sensors are often chosen for precision process control where accuracy and stability are critical.
Q: What outputs are available?
The transmitter offers 4-20 mA, 0-5 V, 0-10 V and RS485 outputs. The 4-20 mA loop is standard for process control, voltage outputs suit data acquisition, and RS485 provides digital networking for multi-drop systems.
Q: What is the measurement range?
The measurement range is 0 to 1000 psi, covering typical process pressure applications. The span is configured for the specific process, and the transmitter is calibrated so the output corresponds to the required range.
Q: What is the protection grade?
The housing is IP67/IP68 rated, protecting against dust and water ingress, including temporary immersion. This makes the transmitter suitable for washdown areas, outdoor installations and other harsh or wet environments.
Q: What power supply does it need?
It operates on a 12-36 V DC supply, with 24 V DC being the typical industrial standard. The wide supply range provides flexibility for different plant power systems.
Q: What is the long-term stability?
The capacitive sensing principle provides excellent long-term stability with low drift, reducing the need for frequent recalibration. This lowers maintenance cost and ensures the measurement remains accurate over the transmitter's service life.
Q: What media can it measure?
It measures gas and liquid media compatible with the wetted materials. Capacitive transmitters are used on process liquids, chemicals, water, refrigerants and process gases. For aggressive media, the wetted material compatibility should be confirmed.
Q: How is it installed?
The transmitter is installed via its process connection into the pressure tap, with the electrical connection via an M12 connector. The output — 4-20 mA, voltage or RS485 — is wired to the control system, and the transmitter is ranged for the application.
Q: Where is it used?
It is used in chemical process control, batching and dosing, water and pump stations, HVAC chillers and any process requiring high-precision, stable pressure measurement. Its IP67/IP68 rating and multi-output support make it versatile for demanding applications.
