Marconi and Tesla worked apparent magic, transmitting and receiving 'aether' and modulating amplitude or frequency to carry clicks and voices. But 'wireless' air had become dangerously crowded, reports Edmond Furter.
Radio frequency (RF) applications now include communications, remote monitors, remote control, commercial communication services, microwave, security signals, and satellite tracking.
Wireless detonation of explosives brought immediate advantages some years ago, in reducing consumables and time, while increasing safety.
Now, crowding of 'air' with ever more and elaborate applications, like satellite hot spots for laptop links, makes accidental detonation of primed explosives or unstable materials, by stray frequencies, almost inevitable, said the National Institute of Explosives Technology (NIXT).
The current generation of electronic initiation systems is immune to radio frequencies, WiFi, lightning and static charges, since they require a signal at a certain voltage, and in an encoded firing signal pattern, explained initiation specialist Carlos Goncalves at the Hard Rock Safety conference in August. "There is a large difference in safety between former electric initiation, and new electronic initiation systems", he said in a talk on centralised blasting systems.
RF ban not practical
The current Department of Labour ban on wireless systems at explosives plants, that could be extended to mines, pose a dilemma. Operators could not possibly ban electronics, nor shield all frequencies outright.
The RF devices ban seems justified, since the susceptibility of several systems in use, and the RF profile of most commercial devices, are unknown.
Manufacturers and their consultants proposed instead a set of restrictions on power levels and frequencies used, and zoning of plants and sites to allow safe use of wireless systems.
Explosives (EX) manufacturers and users agree that a ban on RF would not solve potential Sheq problems, since 'we could not work without it'.
RF safety guide plan
In the interim, the DOL does grant exemptions. Meanwhile, the National Institute of Explosives Technology (NIXT) is drafting a guide on RF devices, supported by the DMR, Sasol, AEL, and test ranges, where RF devices are a necessity.
NIXT is considering a three zone system;
RF zone 3; Low RF risk environment, materials insensitive to electro-magnetic (EM) effects, maximum effective radiated power (ERP) of 5 Watt. RF zone 2; Intermediate RF risk, process-critical electronic equipment, environment-compliant LAN, Wifi, Bluetooth, frequencies 2.4 GHz and upwards allowed, maximum ERP of 100 milli Watt. RF zone 1; high RF risk, safety critical operations on sensitive materials, RF excluded unless EMC compliance and risk assessment, as for new plant, is demonstrated.
Existing explosives plants should determine their RF risks by a detailed risk assessment and Hazop study, and limit procurement of communications and other RF equipment to relevant compliance.
NIXT also recommends consultation with management and technical staff, and incorporating general RF rules into relevant standard procedures.
The Department of Mineral Resources may follow the initiative by standardising the NIXT guide, adding test standards and compatibility tables for use by manufacturers, suppliers and users.
RF versus EX A battle for safe frequencies
Marconi and Tesla worked apparent
magic, transmitting and receiving 'aether' and modulating amplitude or frequency to carry clicks and voices. But 'wireless' air had become dangerously crowded, reports Edmond Furter.
Radio frequency (RF) applications now include communications, remote monitors, remote control, commercial communication services, microwave, security signals, and satellite tracking.
of electronic initiation systems is immune to radio frequencies, WiFi, lightning and static charges, since they require a signal at a certain voltage, and in an encoded firing signal pattern, explained initiation specialist Carlos Goncalves at the Hard Rock Safety conference in August. "There is a large difference in safety between former electric initiation, and new electronic initiation systems", he said in a talk on centralised blasting systems.
Wireless detonation of explosives brought immediate advantages some years ago, in reducing consumables and time, while increasing safety.
Now, crowding of 'air' with ever more and elaborate applications, like satellite hot spots for laptop links, makes accidental detonation of primed explosives or unstable materials, by stray frequencies, almost inevitable, said the National Institute of Explosives Technology (NIXT).
The current generation
RF ban not practical
The current Department of Labour ban on wireless systems at explosives plants, that could be extended to mines, pose a dilemma. Operators could not possibly ban electronics, nor shield all frequencies outright.
The RF devices ban seems justified, since the susceptibility of several systems in use, and the RF profile of most commercial devices, are unknown.
Manufacturers and their consultants proposed instead a set of restrictions on power levels and frequencies used, and zoning of plants and sites to allow safe use of wireless systems.
Explosives (EX) manufacturers and users agree that a ban on RF would not solve potential Sheq problems, since 'we could not work without it'.
RF safety guide plan
In the interim, the DOL does grant exemptions. Meanwhile, the National Institute of Explosives Technology (NIXT) is drafting a guide on RF devices, supported by the DMR, Sasol, AEL, and test ranges, where RF devices are a necessity.
NIXT is considering a three zone system;
RF zone 3; Low RF risk environment, materials insensitive to electro-magnetic (EM) effects, maximum effective radiated power (ERP) of 5 Watt. RF zone 2; Intermediate RF risk, process-critical electronic equipment, environment-compliant LAN, Wifi, Bluetooth, frequencies 2.4 GHz and upwards allowed, maximum ERP of 100 milli Watt. RF zone 1; high RF risk, safety critical operations on sensitive materials, RF excluded unless EMC compliance and risk assessment, as for new plant, is demonstrated.
Existing explosives plants should determine their RF risks by a detailed risk assessment and Hazop study, and limit procurement of communications and other RF equipment to relevant compliance. NIXT also recommends consultation with management and technical staff, and incorporating general RF rules into relevant standard procedures.
The Department of Mineral Resources may follow the initiative by standardising the NIXT guide, adding test standards and compatibility tables for use by manufacturers, suppliers and users.
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