Read Flammable and Combustible Liquids Overview
to determine the hazard classification of your material.
The hazard classification of a liquid determines the type and size of container in which it may be stored.
Bonding and grounding is the process of providing an electrically conductive path between a dispensing container, a receiving container, and an earth ground. This pathway eliminates the potential buildup of static electricity and possible spark that can cause a flash fire if there is a flammable mixture of fuel and air.
- See a diagram of a bonded and grounded configuration.
Read about applicable requirements and definitions, and how to ground and bond below. Glass containers are excluded.
Class 1 Flammable Liquids must be bonded and grounded when transferring liquids in accordance with Code of Federal Regulations, 29 CFR 1910.106(e)(6)(ii):
"Grounding." Class I liquids shall not be dispensed into containers unless the nozzle and container are electrically interconnected. Where the metallic floorplate on which the container stands while filling is electrically connected to the fill stem or where the fill stem is bonded to the container during filling operations by means of a bond wire, the provisions of this section shall be deemed to have been complied with.”
- Bonding is the process of connecting 2 or more conductive objects together by means of a conductor so that they are at the same electrical potential, but not necessarily at the same potential as the earth [NFPA 77 - 3.1.2].
- Grounding is the process of bonding 1 or more conductive objects to the ground, so that all objects are at zero (0) electrical potential; also referred to as "earthing" [NFPA 77 - 3.1.10].
- Grounding plate is a metal plate used to provide a bond for the receiving container.
- Grounding rod is an easily cleaned nonreactive metal rod designed to provide a bonding point for containers that are too small or that have no metal attachment point.
- Static electric discharge is a release of static electricity in the form of a spark, corona discharge, brush discharge, or propagating brush discharge that might be capable of causing ignition under appropriate circumstances [NFPA 77 3.1.16].
How to bond and ground
- See Lab Safety Supply's Bonding and Grounding Fact Sheet for a good overview reference.
- Carefully assess and identify a safe location, avoiding:
- Poorly ventilated spaces
- Open flames or heat sources (e.g., hot plates, Bunsen burners etc)
- Electrically charged equipment
- Transfer flammable liquids within a chemical fume hood when possible and in a proper dispensing location such as a high hazard room (flammable room) or well-ventilated laboratory room.
- Use proper bonding and grounding cables:
- Plastic coated 10' coiled grounding cable with clamps on both ends work well (see image below). Some locations may have permanent cables available.
- Braided 3' bonding cable with alligator clips on both ends work well (see image below).
- Find an earth ground (copper water lines work well) and label it for future reference. Do not use fire sprinkler lines!
- Remove dirt, debris, paint, etc., to ensure a good metal to metal connection.
- Connect the dispensing vessel to the earth ground.
- Place receiving vessel in a secondary container or on a bonding metallic floorplate.
- Connect the bonding cable from the receiving vessel to the dispensing vessel or floorplate (metal to metal).
- Note: If the receiving container is too small, does not have a metal connection, or you do not have a metal floorplate, provide a grounding rod (use care that it does not tip over).
- Once properly connected, proceed with your transfer.
- When complete, disconnect all bonding and grounding cables and remove the grounding rod if applicable.
- Clean all equipment and properly transport the material to the laboratory.
- Leave the bonding and grounding equipment readily available for the next person to use.
2 examples of bonding and grounding configurations.