Static Electricity 2000 Edition
Nonconductive Portable Tanks and IBCs
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NFPA 77 Static Electricity
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- 7.13.3 Metal Containers.
7.13.2 Nonconductive Portable Tanks and IBCs.
Filling a non- conductive portable tank or IBC with combustible liquids at temperatures below their flash points presents no significant static electric ignition hazard. Filling such a vessel with a com- bustible liquid above or within 9 °C of its flash point should be done as if the liquid were flammable. Refilling a vessel that could contain flammable vapors from a previous product should not be allowed. Additionally, the routine handling of nonconductive vessels filled with any type of liquid can generate a charge on the outside surface of the vessel. Nonconductive portable tanks and IBCs should not be used where ignitible ambient vapors are present. FLAMMABLE AND COMBUSTIBLE LIQUIDS AND THEIR VAPORS 77 –25 2000 Edition Portable tanks and IBCs constructed of nonconductive materials are prohibited for use with Class I liquids by NFPA 30, Flammable and Combustible Liquids Code. Where such con- tainers are used for Class II and Class III liquids, the precau- tions for filling depend on the size of the container, the container design, and the conductivity of the liquid. 7.13.3 Metal Containers. When being filled, metal contain- ers and associated fill equipment should be bonded together and grounded. Bonding should be done with a clamp having hardened steel points that will penetrate paint, corrosion products, and accumulated material using either screw force or a strong spring. (See Appendix C for recommendations.) The clamp should be applied prior to removing the container bungs and at a point on the top chime that is located away from the bung openings. The grounded fill pipe should be cut at approximately 45 degrees and be left relatively sharp to inhibit brush discharges from the liquid surface. The tip of the fill pipe should extend to within 25 mm of the bottom of the drum and remain beneath the liquid surface until the drum is filled. Viscous liquids that flow without splashing can be deflected by a short fill nozzle to flow down the inside wall of the drum. Inerting of the drum is seldom necessary. When dispensing from a metal container, it should be grounded. Self-closing, metal dispensing valves should be used. When dispensing from an upright drum, the dip pipe, conductive hose, and pump should be bonded to the drum and grounded. (For funnels and receiving containers, see 7.13.6.) Download 1.59 Mb. Do'stlaringiz bilan baham: |
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