NAMUR proximity sensors are 2-wire intrinsically safe devices built for hazardous areas — chemical plants, solvent handling, oil and gas installations and paint shops — where a conventional switching sensor could produce an ignition source.
How NAMUR sensors work
A NAMUR sensor is deliberately simple: an LC oscillator whose current draw changes when metal approaches the sensing face. It does not switch a load itself. Instead it presents a low current (typically under 1 mA) when damped and a higher current (above 2.2 mA) when undamped.
That current signal is read by a separate switching amplifier or isolating barrier mounted in the safe area of the panel. Because the sensor contains no switching electronics and the barrier limits available energy, the circuit entering the hazardous zone cannot store or release enough energy to ignite an explosive atmosphere.
A NAMUR sensor is only intrinsically safe as part of a certified loop. It must be paired with a matching NAMUR switching amplifier or Zener barrier, and installed per the barrier's certification documents.
Standards
These sensors comply with the NAMUR recommendation implemented as DIN 19234, now published as EN 60947-5-6 (often written IEC 60947-5-6). That standard fixes the electrical characteristics so any compliant sensor works with any compliant amplifier.
Advantages over a standard proximity sensor
- No ignition risk — no switching contacts and strictly limited circuit energy.
- Very high reliability — the simple oscillator design has few failure modes.
- Line monitoring — the amplifier detects both open-circuit and short-circuit cable faults, which a normal sensor cannot report.
- Safety-system compatible — integrates with ESD and interlock systems through standard barriers.
Limitations to plan around
- Requires an external switching amplifier, which adds panel cost and DIN-rail space.
- Cannot drive a load directly — it only produces a current signal.
- Cable routing and segregation must follow intrinsic-safety installation rules.
Technical specifications
| Parameter | Value |
|---|---|
| Type | 2-wire NAMUR inductive sensor |
| Standard | DIN 19234 / EN 60947-5-6 |
| Supply | 8.2 V DC nominal, from the NAMUR amplifier |
| Current — target absent | > 2.2 mA (undamped) |
| Current — target present | < 1.0 mA (damped) |
| Rated switching distance | 1.5 mm to 12 mm, depending on barrel size |
| Housing material | Stainless steel or chrome-plated brass |
| Protection class | IP68 |
| Available sizes | M8, M12, M18, M30 |
| Required accessory | NAMUR switching amplifier or isolating barrier |
Typical applications
- Chemical and pharmaceutical plants — valve position feedback in solvent areas.
- Oil, gas and petrochemical installations — pump and actuator monitoring.
- Paint and coating lines — position sensing in flammable-vapour zones.
- Grain, sugar and flour handling — dust-explosion risk areas.
How to order
Tell us the sensing gap, the target material, your supply voltage and the output type your controller needs. If you are replacing an existing sensor, a photograph of the body markings is usually enough for us to identify an equivalent. We will confirm the specification and quote — normally the same day.
Related products
Frequently asked questions
Do I need a separate amplifier with a NAMUR sensor?
Yes, always. The NAMUR sensor produces only a current signal; a NAMUR switching amplifier or isolating barrier in the safe area converts that into a usable relay or transistor output and provides the energy limitation that makes the loop intrinsically safe.
Is a NAMUR sensor the same as an ATEX-certified sensor?
They are related but not identical. NAMUR / DIN 19234 defines the electrical behaviour that makes intrinsically safe operation possible. ATEX and IECEx are certification schemes covering the whole installation. Tell us the zone classification and required certification for your site and we will confirm what we can supply.
Can I use a NAMUR sensor in a normal, non-hazardous machine?
You can, but there is rarely a reason to. In a safe area a standard 3-wire DC sensor is cheaper, needs no amplifier and drives loads directly. NAMUR types are chosen for cable-fault monitoring or hazardous-area compliance.
Need a quote for the NAMUR Proximity Sensor (Intrinsically Safe)?
Send us your application — target material, sensing distance, supply voltage and housing constraint. We will recommend a part, quote it, and ship from Mumbai.