NAMUR

NAMUR proximity sensors are specialized 2-wire, intrinsically safe devices designed for hazardous environments (e.g., chemical, oil & gas industries). They comply with DIN 19234 and NAMUR standards, ensuring safe operation in explosive atmospheres.

Advantages Over Standard Proximity Sensors

✔ Explosion-proof (no spark risk).
✔ Reliable (low failure rate due to simple oscillator design).
✔ Compatible with safety systems (via amplifiers).

Limitations

✖ Requires external amplifier (additional component).
✖ Limited output current (cannot directly drive loads).

Key Features

1. Intrinsically Safe Design

   • Low energy output prevents ignition in hazardous areas.

   • Requires an external amplifier (evaluator/interface) for signal processing.

2. Operating Principle

   • No target present: Current > 3mA (open circuit state).

   • Target detected: Current < 1mA (closed circuit state).

   • Nominal voltage: 8V DC (operating range: 8–12V DC).

   • Series resistance: 1kΩ (limits current to safe levels).

3. Technical Specifications

   • Sensing range: 1mm – 50mm.

   • Hysteresis: 5–10% of sensing distance.

   • Repeatability: 5–10% of sensing distance.

   • Switching frequency: Up to 1 kHz.

   • Housing: Chrome-plated brass (corrosion-resistant).

   • Protection: IP68 (dustproof & waterproof).

   • Short-circuit & reverse polarity protection: Yes.

   • Mounting options: Flush or non-flush.

4. Wiring & Amplification

   • 2-wire DC connection (no internal switching contacts).

   • Requires an isolated barrier/amplifier (e.g., NAMUR relay, IS barrier) to interface with PLCs/DCS.

5. Applications

   • Hazardous zones (ATEX/IECEx certified).

   • Liquid/gas detection in chemical plants.

   • Position sensing in explosive environments.