NAMUR sensors solve the same applications that standard inductive and capacitive sensors or rotary encoders would—but they are safe to use in hazardous areas. NAMUR output sensors are ideal for applications where the presence of a volatile gas, vapor, dust, or fiber creates a possible hazard.
To prevent an explosion in hazardous areas, these sensors protect the circuit by operating at 8.2 V and less than 5 mA. These levels prevent the device from storing sufficient energy to initiate an explosion. NAMUR sensors are connected to an isolating amplifier, which limits the current and voltage to the sensor and amplifies the signal upon return.
For more information about how these sensors work, read our blog post Why Would I Use a NAMUR Output Sensor?
Does your application require a NAMUR sensor? To help you decide, here are some applications that the sensors commonly solve:
Sensors are used throughout pharmaceutical manufacturing processes. Since volatile chemicals used in these processes create hazardous areas, NAMUR sensors are needed. In storage tanks, for instance, NAMUR sensors monitor fill level. Capacitive sensors are used here, because they can detect substances through nonconductive sight glasses. Another common application is using inductive NAMUR sensors for presence detection in sterilization chambers—for example, ensuring that a door is completely closed.
In paint manufacturing, raw materials including pigments, solvents, and other chemicals are processed and mixed. Many of these chemicals are volatile and may emit flammable gases and vapors. Accordingly, conveyor systems that move paint cans through the filling and sealing process use inductive NAMUR sensors to detect the presence of the cans. In automotive manufacturing, inductive NAMUR sensors are used in paint booths to ensure that doors are completely shut during the painting process.
NAMUR sensors are well suited to metering applications. Common metering applications for NAMUR devices include using flow meters to measure quantities of gases, counting the number of sprockets on a gear, detecting whether a meter is in the open or closed position, and monitoring rotation. Situations also arise in the metering industry where high switching frequency is required. NAMUR sensors meet this requirement due to containing only a coil and oscillator. Metering applications typically use inductive NAMUR sensors due to the metal components of the meters Hazardous-area NAMUR rotary encoders are also used in metering applications.
HVAC systems provide buildings with heating, ventilation, and air conditioning via ductwork. Fire suppression systems are implemented within the ductwork to detect the accumulation of flammable dusts. Capacitive NAMUR sensors monitor the layer thickness of dust and will trigger the output if too much dust is present.
Oil and Gas
The oil and gas industry deals extensively with volatile materials, so NAMUR outputs are naturally found throughout the industry. Applications include presence detection for offshore and land drill rigs in locations such as the deck, top drive, pipe racker, drawworks, and blowout preventer. These applications use inductive NAMUR sensors because the targets are metal. Refineries also use capacitive NAMUR sensors for level detection.
Vapors emitted from the mixture of chemicals pose an explosion hazard in the production of fluids. For instance, to make windshield washer fluid, glycol, water, and other substances are combined. NAMUR sensors are used to monitor levels in storage tanks. In this case, capacitive NAMUR sensors monitor fluid level through sight glasses.
Powders pose a hazard in a wide range of industrial automation applications. In the airbag manufacturing process, machines load powder into the initiator components that trigger airbag inflation. NAMUR sensors are used here due to the combustibility of the powder.
Presses and Process Machinery
Sensors provide level and stroke feedback on presses and processing machinery. High temperatures and pressure are common throughout the process industry. Combining these conditions with a volatile material results in the need for NAMUR sensors.