
API and NFPA guidelines recommend that such bonding connections are tested to verify an adequately low resistance to earth/ground prior to starting up the recover/transfer process, however until now the equipment required to do this required specialist training and may not always have been suitable for safe use within the hazardous atmosphere. Furthermore, long delays and downtime can sometimes be experienced while waiting for a qualified electrician to sign off that the truck is properly bonded and grounded before the operation commences.
The new truck mounted Earth-Rite® MGV (patent pending) derives its power source from the vehicle battery, and uses certified Intrinsically Safe monitoring techniques to verify not only a good bond to a valid ground point, but more importantly confirmation that the ground point to which it is attached represents a satisfactorily low resistance to true earth. The unit is simple to install and operate and provides confirmation of positive bonding and grounding to the operator by way of a bright flashing green LED cluster. It also provides a pair of change over contacts (DPDT) for connection to additional safety devices (strobe lights, audible alarms) or for interlocking with the vacuum pump or control valve. The “business end” of the system employs a heavy duty stainless steel clamp with universal clamping jaw which can be connected to flat or rounded surfaces, including directly to ground rods.
Units have obtained Intrinsically Safe certification for use in the Global Petrochemical Industries, according to the requirements of IECEX, ATEX, CSA/US and NEPSI (China), and may be used in all common gas, vapour or dust explosive environments.
Several sites in Europe, North America and Australasia are already using the system for their hazardous area vacuum truck operations with reports of enhanced safety, improved productivity and robust product reliability. The system is also useful for flammable liquid or combustible bulk material delivery tankers involved in chemical distribution and similar operations.
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