Example of correct earthing technique for a static dissipative drum.
If a grounded metal surface for the drum to sit on is not possible, then two separate clamps can be mounted on opposite sides of the top rim of the drum. Alternatively, a single 2 pole clamp can monitor the integrity of its connection to the drum via two tips located on the earthing clamp. Depending on the preferred method of connection, the earthing system is proving that the drum is connected to ground for the duration of the filling process.
The earthing system should be interlocked with the drum filling line so that if the drum has not been grounded by the operator, or the drum is not static dissipative, filling cannot take place ensuring hazardous static charges cannot accumulate on the drum.
If plastic portable containers are to be used in hazardous areas it important to ensure the containers are capable of safely dissipating static electricity when they are earthed. In order to remove the risk of incendive electrostatic ignitions, the material of the container, and especially the surface exposed to the hazardous atmosphere should be static dissipative. When containers are being filled or emptied it is equally important to use static earthing systems that can determine if the drum is actually static dissipative to a maximum resistance of 1 x 108 ohms. This will ensure that “rogue” containers made of normal plastic cannot be used in the hazardous area. A static earthing system will also ensure that the static dissipative content of the container has not degraded through normal lifecycle effects and is reliably performing its intended safety function of dissipating potentially hazardous electrostatic charges from its surface once it has been connected to earth.
If you require information on earthing techniques for static dissipative containers including drums and IBCs please contact Newson Gale.
(1) “Electrostatic Ignitions of Fires and Explosions”, Pratt, T.H., Center for Process Chemical Safety (2000).
(2) Research Report RR804 “Plastic Containers for flammable liquids/hazardous areas, Electrostatic Risks”, Health & Safety Laboratory (2010).
(3) Guidance Notice 51a, “Use of IBCs for Oxygenated Solvents and Hydrocarbon Solvents”, Solvents Industry Association & Chemical Business Association, (2003).
(4) “Avoiding Static Ignition Hazards in Chemical Operations”, Britton, L.G., Center for Process Chemical Safety (1999).
(5) CLC/TR 50404: “Electrostatics. Code of practice for the avoidance of hazards due to static electricity”, CENELEC (2003).
Mike O’Brien, Managing Director for Newson Gale
If you have any questions relating to the topics discussed in this article,
please contact Newson Gale.