Know-How ATEX
ATEX explication: (ATEX pressure equipment complexity)
Starting from an internal overpressure of > 0.5 bar, pressure equipment or valves fall within the scope of the Pressure Equipment Directive 2014/68/EU. The applicability of the ATEX Directive 2014/34/EU Article 2 (4.) and the harmonized standard DIN EN ISO 80079-36 refers only to usual atmospheric conditions.
These conditions are defined as follows:
- Temperature range –20 °C to +60 °C;
- Pressure 80 kPa (0.8 bar) to 110 kPa (1.1 bar); and
- Air with usual oxygen content, normally 21 % (V/V)
This means that atmospheric conditions will not prevail in the pressurized interior of a pressure device during operation (pe 0.5 bar > pamb 1.1 bar or pabs 1.6 bar > pabs 1.1 bar).
In the event of installation, commissioning and decommissioning, as well as in case of a malfunction, atmospheric conditions may occur in the otherwise pressurized interior of the pressure equipment. Our ignition hazard assessment considers potential ignition sources also in the pressure chamber under atmospheric conditions.
Explosions can also occur under non-typical atmospheric conditions, called explosive mixtures (combustion engine). The limit values from the above-mentioned ATEX regulations do not apply to this and must be investigated by the operator of the plant. The operator must take suitable protective measures to avoid the explosive atmosphere and the explosive mixture inside the valve (pressure chamber).
Selection criteria for equipment and protective systems
In all areas where explosive atmospheres may be present, equipment and protective systems must be selected according to the equipment group and the EPL in accordance with ATEX Directive 2014/34/EU.
Temperature classes
Our pressure equipment for use in hazardous areas has no or only a very low self-heating. At Mankenberg, the max. surface temperature, which has to be marked, depends primarily on the temperature of the medium flowing through.
Accordingly, a specification of the temperature class T1 or T6 is not permissible and is indicated with a range
for ex. T6 …T4 or +85 °C …+130 °C.
Consequently, our devices can also be used in potentially explosive atmospheres with temperature class requirements = T3 to T1, since the max. surface temperature of the devices cannot exceed 155 °C if the max. operating temperature is limited at 130 °C.
Mankenberg products can also be used in hazardous areas with requirements for temperature classes T6 to T4.
Here, it is mandatory to deduct the ATEX safety surcharge of 25 °C from the respective required temperature class (max. permissible surface temperature specification of the devices to be used).
Example: The gas carbon disulfide, ignition temperature 95 °C, required temperature class of the device T6 (max. surface temperature = 85 °C).
The max. operating temperature here may only be 85 °C - 25 °C = 60 °C.
Admissible ambient temperature
The admissible ambient temperature must be specified if it is beyond the range -20 °C to +60 °C.
A temperature range other than normal is indicated by X or e.g. -10 °C ≤ Ta ≤ +130 °C.
» Ex II 2G Ex h IIB 85°C...130°C Gb X
The letter "X" in the ATEX device marking draws the customer's attention to special conditions when handling the device. These instructions are described in the operating manual.
Temperature assignment of temperature class and operating temperature
Ignition temperature and temperature class
The table shows the relation between the explosion group gas (the individual ignition temperature of exemplary gases) and the temperature class required with it (max. device surface temperature) of the devices to be used.
