Humidity and Temperature Transmitter - ATEX Approved
(Explosion-Proof) Humidity and Temperature Transmitters - ATEX Approved, are specialized devices designed for safe measurement in hazardous areas with explosion risk (Zone 0, Zone 1, Zone 2). These devices have internal housings that prevent a spark or heat from igniting flammable gases or dust in the environment.
Key Features and Protection Classes
The biggest difference between these devices and standard transmitters is their housing structure and energy limiting capacity:
- Housing Structure: Flameproof housings, typically made of electrostatically powder-coated cast aluminum or stainless steel (316L), are used.
- Certification: ATEX (European) or IECEx (Global) certifications are mandatory. The device label will include markings such as Ex d (Flameproof) or Ex ia (Intrinsically safe).
- Sintered Filter: The metal filter located at the sensor tip allows gas to pass through while preventing a potential blast wave from escaping or entering.
Assembly and Connection Details
When installing in explosion-proof sites, the following technical aspects are of vital importance:
- Cable Glands: Ex-proof certified brass or stainless steel glands must be used at the transmitter cable entry. Standard plastic glands cannot be used in these areas.
- Isolator/Barrier Usage: If the device is of the "Ex ia" (intrinsically safe) type, it must be powered via a Zener Barrier or Galvanic Isolator in the panel. This limits the energy going to the site to a level that will not cause an explosion.
- Sealing: Housing covers and cable entries must be sealed with IP66 or IP67 protection class to prevent ambient moisture from reaching the electronic circuitry.
Areas of Application
These devices are standard in the following industries where flammable materials are present in high concentrations:
- Petrochemical and Refinery Plants: Crude oil processing and storage facilities.
- Paint and Chemical Plants: Environments containing flammable solvents and chemical vapors.
- LPG/Natural Gas Stations: Enclosed spaces with a risk of gas leaks.
- Pharmaceutical Manufacturing Facilities: Raw material processing units that carry a risk of dust explosions.
- Grain silos and flour mills: Areas with high concentrations of organic dust.
Things to Consider When Making a Choice
Zone: Is the area where the device will be used Zone 0 or Zone 1/2?
Gas Group: The type of gas present in the environment (e.g., group IIC should be selected for hydrogen, group IIB for ethylene).
Temperature Class: Classes from T1 to T6 (Determines the limit of the device surface temperature).
Probe Length: The depth (stalk) of the probe that will enter the tank or channel.