Mike Dolt Enterprises
Mike Dolt Enterprises
User: brock.aslan, Location: Ohio
Asked on: Saturday, February 8, 2025 at 1:36 pm EST
Answered on: Thursday, March 6, 2025 at 8:25 am EST
Question: My previous post might not be as applicable if the answer to this questions is "yes":Are NAMUR Proximity Sensors considered to be Simple Apparatuses (definitionally speaking)? NFPA 70 definition below...For instance, is a Pepperl+Fuchs CCB10-30GS55-N1-V1 capacitive sensor a simple apparatus? I tend to think that it is NOT, but any mfg websites seem to be hinting that because it's NAMUR/low-power it is considered a simple apparatus.Simple Apparatus: n electrical component or combination of components of simple construction with well-defined electrical parameters that does not generate more than 1.5 volts, 100 milliamps, and 25 milliwatts, or a passive component that does not dissipate more than 1.3 watts and is compatible with the intrinsic safety of the circuit in which it is used.
You're right to question whether a NAMUR proximity sensor is a simple apparatus. The answer is generally NO, and your reasoning is sound.Here's why: NAMUR sensors are NOT passive components
While they operate on low power, they are active devices. They contain transistors or other semiconductors to perform the switching function based on proximity. They generate a signal, even though that signal is low power.
Exceeding the Simple Apparatus Limits
While a NAMUR sensor is low power, you need to look at the voltage, current, and power it generates to determine if it falls within the NFPA 70's limits for simple apparatus. It must meet ALL of the criteria: no more than 1.5 volts, 100 milliamps, and 25 milliwatts. A typical NAMUR sensor, even in its 'high' or 'low' state, can often exceed one or more of these limits.
Pepperl+Fuchs CCB10-30GS55-N1-V1 specifically
This capacitive sensor from Pepperl+Fuchs will almost certainly not be a simple apparatus. Capacitive sensors inherently need to generate an electric field and detect changes in capacitance. This requires active circuitry and will almost certainly exceed the simple apparatus limits.
Manufacturer "Hinting" vs. Certification
Manufacturers might hint at something being "inherently safe" or "low power," but this doesn't automatically make it a "simple apparatus" according to NFPA 70. The specific electrical parameters must be verifiable and compliant with the definition. Look for specific certifications (e.g., ATEX, IECEx, UL) that explicitly state the sensor is suitable for use as a simple apparatus. These are rare for any active sensor.
In Summary
Don't be misled by the "low power" or "NAMUR" designation. A NAMUR proximity sensor is, generally, an active device and must meet the strict definition of a simple apparatus to be considered one. Active sensors, even low-power ones, rarely meet all three of the simple apparatus criteria, especially voltage and wattage. The Pepperl+Fuchs CCB10-30GS55-N1-V1 is highly unlikely to be a simple apparatus.
Always consult the manufacturer's datasheet and any relevant certifications to confirm.What Does This Mean for Intrinsic Safety Applications?
Because the Pepperl+Fuchs CCB10-30GS55-N1-V1 is probably NOT a simple apparatus, for use in hazardous locations, it would need to be part of a certified intrinsically safe (IS) system. This typically involves:1. The Sensor Itself
The sensor needs to be certified for the specific hazardous area (e.g., Class I, Division 1, Group A-D).2.
An IS Barrier
The sensor is connected to a barrier device in the safe area. This barrier limits the voltage and current that can flow into the hazardous area, preventing ignition.3.
Certified Cable: The cable used to connect the sensor to the barrier must also be certified for IS applications.Don't assume a sensor is safe just because it's NAMUR. Understand the limitations and rely on certifications and proper system design. Always consult with qualified experts for intrinsically safe system design and installation. Flag for review