From the standards: Radio Frequency Sources (9kHz to 60GHz) for continuous transmissions and pulsed transmissions whose pulse duration exceed the thermal initiation time shall not exceed limits below:
However, for Group I in South Africa, there were DMR directives (ME-2-2003 signed; MS-2-2010 unsigned) that contradict IEC/SANS60079-0 standard of 6W RF transmission stipulating 500mW.
Wifi underground offers huge safety & operational improvement. – communications; training, access to documentation & virtual remote support; remote eyes & Real Time Location Tracking RTLS with efficient mustering etc.
Typically APs transmit at 100mW, so provided sensible gain antennae are used, there is no concern with respect to the 500mW limit anyway.
Wifi can be done as an Exd Flameproof solution, but Exd antennae are limited. Using the iSolate501 RF Galvanic isolator can be used to use an antenna as simple apparatus in an IS loop. Extronics also supply the Exd iSolateCT connector which enables antennae to be slickly routed out of the enclosure compared to using cable glands.
So how do you do an IS RF loop approval? Please see loop drawings below for Group I & Group IIC/IIIC
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