Static electricity (or, scientifically speaking, a difference in electrical potential between two objects) is a serious concern for anyone who moves flammable liquids from one container to another. Not sure why you should be worried? Picture that zap you get when you drag your feet on a carpeted floor, then touch a doorknob or another person. It’s not a big deal, but it sure gets your attention.
That little jolt is actually a spark that’s created when your electrical charge (built up by your feet dragging on the carpet) equalizes with the other object’s charge. Now, picture that spark occurring while you stand in a cloud of flammable fuel vapor while filling a tanker. That is a much bigger deal, and it’s likely to get the attention of anyone within earshot.
Static Electricity While Loading
It may seem like weird science, but static electricity is created by a build-up of differently charged ions that occurs naturally when objects (including liquids and gases) move against one another.This type of build-up can take place when liquid products are top-loaded into tanks. The build-up can produce a static electrical spark between the loading nozzle and the tank opening or cover. If flammable vapors are present when the spark occurs, you might have a front row seat to an explosion or a fire.
Preventing Static Build-Up
To minimize the risk of a static-ignited incident, it’s important to use a static bonding cable when transferring flammable or combustible liquids between containers (at temperatures above the flash points of the liquids). The static bonding/grounding cable should be connected to the load piping, tanks and a metal stake installed at least 7 feet into the earth.Using the Cable Correctly
The bonding cable is designed to equalize the static electrical charge and prevent a static spark. Before loading tank vehicles through open dome covers, make a bonding connection between the loading tank and the vehicle/tank before dome covers are raised.The connection should remain in place until filling is complete and all dome covers have been closed and secured.
More Fire Prevention Tips
Hopefully your drivers are already correctly bonding and grounding their trucks every time they fill. For extra credit, make sure you’re also following these other fire prevention practices:- Remove (or strictly control) ignition sources within 25 feet of all areas where fuel transfer operations occur, and where vehicles are driven or repaired.
- Equip all bulk fuel plants and tank trucks with fire extinguishers (minimum rating of 40 B:C).
- Post “no smoking” signs at the loading rack, unloading risers, tanks and at all access points throughout the plant. Then enforce this rule whenever you see it being violated.