Wireless devices are a niche market, and new technologies are rarely offered in hazardous area versions when they first hit the market.

Implementing wireless technologies in industrial settings is far from straightforward compared to office or factory environments. Heavy industry presents unique challenges and conditions, including dense metal infrastructure and hazardous environments such as potentially explosive atmospheres. There are many reasons for deploying wireless technologies in hazardous areas. In almost all cases, the goal is to ensure connectivity and improve the appearance of the hazardous area.

Successful deployment of a wireless network most often requires the installation of a radio system with antennas directly in the hazardous area. This is usually due to operational difficulties, such as the distance between hazardous and safe areas. There is also a limitation on the length of the RF cable, which causes excessive losses, making the wireless signal unusable.

Conversion of an existing device to one that meets the standards required for operation in hazardous areas. Simple and reliable wireless technology for hazardous industrial environments - explosion-proof dome antennas, explosion-proof 19-inch and 10-inch Ex-rated racks for radio system.

Explosion-proof dome antenna housings for hazardous areas are specially designed for various antennas and other radio components. The materials used are ideal for applications in radio engineering. The antenna components inside the housing dome are compounded and fully protected from all external influences. Various lines of explosion-proof antennas are suitable for use in Wi-Fi application, WiMax, various GSM, 3G, 4G-LTE, 5G modems, GNSS receivers (GPS and others), Bluetooth devices, BLE devices, RFID devices, UWB, LoRaWAN, WiHART/ISA100.11a, TETRA walkie talkies.

The maximum power of the radio frequency field on the surface of the antenna dome is lower than that of the radiated component. This allows the output power to be increased without exceeding the RF power threshold limits for hazardous areas.

IEC requirements of radio frequency sources intended for use in explosive atmospheres. 

The threshold power of radio frequency (9 kHz to 60 GHz) for continuous transmissions and for pulsed transmissions whose pulse durations exceed the thermal initiation time shall not exceed the values shown in Table 5. Programmable or software control intended for setting by the user shall not be permitted.

Table 5 –Threshold power

Equipment for Group /Maximum threshold power W /Maximum thermal initiation time μs

Group I / 6 W / 200 μs

Group IIA / 6 W / 100 μs

Group IIB / 3,5 W / 80 μs

Group IIC / 2 W / 20 μs

Group III / 6 W / 200 μs

For pulsed radar and other transmissions where the pulses are short compared with the thermal initiation time, the threshold energy values Zth shall not exceed those given in Table 6.

Table 6 –Threshold energy

Equipment for Group / Maximum threshold energy Zth μJ

Group I / 1500 μJ

Group IIA / 950 μJ

Group IIB / 250 μJ

Group IIC / 50 μJ

Group III / 1500 μJ

Notes

* In Table 5 and Table 6, the same values are applied for Ma, Mb, Ga, Gb, Gc, Da, Db, or Dc equipment due to the large safety factors involved.

Notes

* In Table 5 and Table 6, the values for Group III are adopted from Group I and not based on experimental results.

Notes

* In Table 5 and Table 6; the values apply in normal operation, provided that the user of the equipment does not have access to adjust the equipment to give higher values. It is not necessary to consider possible increases in power caused by faults, due to the large safety margins involved and the strong likelihood that RF amplifiers will rapidly fail if a fault occurs that significantly increases the output power.

Terms and definitions

Radio frequency:electromagnetic waves from 9 kHz to 60 GHz

Continuous transmission: transmission where the duration of the pulse is greater than half of the thermal initiation time

Pulsed transmission: transmission where the duration of the pulse is shorter than half of the thermal initiation time, but the time between two consecutive pulses, however, is longer than three times the thermal initiation time

Thermal initiation time: time (over which the threshold power is averaged) during which energy deposited by the spark accumulates in a small volume of gas around it without significant thermal dissipation 

Note to entry: For times shorter than the thermal initiation time the total energy deposited by the spark will determine whether or not ignition occurs. For increasingly longer times, the power or rate at which energy is deposited becomes the determining factor for ignition.

Threshold energy Zth: for a pulsed radio-frequency discharge, the maximum energy of the single pulse which can be extracted from the receiving body

Threshold power Pth: product of the effective output power of the transmitter multiplied by the antenna gain 

Note to entry: The gain is produced by an antenna concentrating radiation in a particular direction and is always related to a specified reference antenna 

Note to entry: The threshold power is considered to be equal to the Effective Isotropic Radiated Power (EIRP) per ITU-R BS.561-2.

Antenna gain: gain produced by an antenna concentrating radiation in a particular direction.

Note to entry: The gain of antennas is frequently less than unity

HydITEx specializes in the design and integration of custom explosion-proof antenna solutions that uniquely eliminate the need for intrinsically safe (IS) barriers to reduce signal levels.