Portable containers and refueling safety

Most fuel leaves a station inside a vehicle's tank, which is designed for it. Some leaves in portable containers for lawn mowers, snowblowers, boats, generators, chainsaws and stranded cars. Containers bring their own hazards. A container can build up a static charge and spark while it is being filled. The wrong container can leak, burst or be mistaken for something to drink. And a full container rolling around in the back of a car is a fire waiting for a spark. This lesson covers approved containers, how to fill them safely, the rules on size and number, and the related rules for fueling vehicles: engines off, no topping off and attending the nozzle.

Approved containers

Fire codes allow gasoline and other flammable liquids to be dispensed only into approved containers. Portable plastic fuel containers are made to ASTM F852, and metal safety cans to UL 30 or similar standards. Since 2009 federal rules have required gasoline containers sold to consumers to have child-resistant closures, and the Portable Fuel Container Safety Act of 2020 added a requirement for flame mitigation devices, mesh screens in the spout that stop a flame traveling back into the container. Approved containers are labeled with the fuel they are for and are color coded by custom: red for gasoline, yellow for diesel and blue for kerosene. The color helps prevent a customer pouring the wrong fuel into equipment, but it is the label and the standard mark that make a container approved, not the color.

Unapproved containers turn up at every station: milk jugs, drink bottles, windshield washer jugs, pails with lids, glass jars and old paint cans. They are thin, they dissolve or crack, they have no proper cap, they cannot be identified as containing fuel, and some look like something to drink. Fire codes ban filling them, and the cashier should refuse. Selling an approved container is the easy solution, and Northfield keeps red, yellow and blue ones in stock near the till.

How big, and how many

Fire codes limit the size of portable containers that may be filled at a dispenser. The International Fire Code, adopted in Montana and most states, allows filling only approved containers of up to 6 gal (about 23 L) each, and bans filling any container while it sits in the trunk, passenger compartment or truck bed of a vehicle. NFPA 30A has similar rules. Northfield posts the rule at each pump: approved containers of up to 6 gal each, filled one at a time on the ground.

The station may also have its own limits, for example on how many containers a customer may fill at once, because each container is another chance of a spill or a static spark. The program below checks a customer's request against Northfield's rule and works out how long filling takes at a typical dispenser flow rate.

# Check a container request against the posted rule and estimate filling time (illustrative).
MAX_EACH = 6.0       # US gallons, IFC limit per portable container
FLOW = 10.0          # gallons per minute, federal maximum for light-duty gasoline dispensers
request = [("red can, ASTM F852", 5.0, True), ("red can, ASTM F852", 5.0, True),
           ("milk jug", 1.0, False), ("yellow can, diesel, ASTM F852", 6.0, True),
           ("red can, approved", 8.0, True)]
ok_total = 0.0
for name, size, approved in request:
    if not approved:
        verdict = "REFUSE: not an approved container"
    elif size > MAX_EACH:
        verdict = f"REFUSE: larger than {MAX_EACH:.0f} gal limit"
    else:
        verdict = "ok, fill on the ground"
        ok_total += size
    print(f"{name:32}{size:5.0f} gal  {verdict}")
print(f"Total allowed: {ok_total:.0f} gal, about {ok_total / FLOW * 60:.0f} s of pumping at full flow")

red can, ASTM F852                  5 gal  ok, fill on the ground
red can, ASTM F852                  5 gal  ok, fill on the ground
milk jug                            1 gal  REFUSE: not an approved container
yellow can, diesel, ASTM F852       6 gal  ok, fill on the ground
red can, approved                   8 gal  REFUSE: larger than 6 gal limit
Total allowed: 16 gal, about 96 s of pumping at full flow

The customer can fill the two approved cans and the diesel can, but not the milk jug, and not the oversized can. Containers fill quickly: at the federal maximum flow rate for light-duty gasoline dispensers, 10 gal per minute, a 5 gal can fills in about half a minute. That speed is one reason containers overflow, and one reason the customer must hold the nozzle and watch, rather than walk away.

Filling a container safely

The rule that matters most is to fill containers on the ground. A container on the ground is connected to earth through the pavement, so static charge built up by the flowing fuel drains away. A container in a truck bed, especially on a plastic bed liner, or on carpet in a trunk, is insulated, so the charge builds up until it sparks, often to the nozzle. Several serious fires have started exactly this way.

• Take the container out of the vehicle and set it on the ground, a safe distance from the vehicle and other people.
• Remove the cap and touch the nozzle to the container before starting the flow, then keep the nozzle in contact with the rim or opening throughout filling. The contact gives static a path to drain.
• Fill slowly, by hand, without the hold-open latch, and stop at about 95% full to leave room for expansion.
• Replace the cap tightly, wipe off any spilled fuel, and let any spill evaporate or absorb it before loading.
• Secure the container upright in the vehicle, away from the passenger compartment if possible, and do not leave it in a hot vehicle.

Engines off, no smoking, attend the nozzle

Fire codes and dispenser signs set a few simple rules for anyone fueling a vehicle. Stop the engine. Do not smoke or use any flame. Stay at the nozzle and outside the vehicle (Lesson 5). Do not top off: once the nozzle clicks off automatically, stop. Topping off overfills the tank, spills fuel on the ground and the customer's shoes, and can flood the vehicle's vapor control system, which then vents fuel. Do not let children operate the pump. And never fuel a vehicle with a person smoking inside or with an obvious leak.

The automatic shut-off in the nozzle works by sensing when fuel covers a small hole near its tip. It stops the flow when the tank is full, or when fuel splashes back, which is why some vehicles click off repeatedly. It is reliable but not perfect: it can fail if the nozzle is not inserted fully, if the vehicle's fill neck is damaged, or if the nozzle is jammed open with an object. Customers sometimes wedge the nozzle trigger with a cap or glove when no latch is provided; this is dangerous and the cashier should ask them to stop.

Special vehicles and equipment

• Motorcycles and small engines: small tanks fill in seconds and overflow easily; fill slowly.
• Boats on trailers: portable boat tanks should be removed and filled on the ground; fixed tanks should be filled with the boat on the trailer, the engine off and people out of the boat.
• Vehicles with roof racks or modified tanks: watch for leaks.
• Farm and construction equipment: some stations do not allow it on the forecourt; diesel lanes may be better.
• Leaking vehicles: refuse to fuel a vehicle that is visibly leaking fuel, and ask the driver to move it away from the pumps if it is safe to do so.

When customers argue

Most customers comply once they understand the rule. Some do not. A customer in a hurry may insist on filling a can in the truck bed, or argue that a milk jug is fine for one trip. The cashier does not need to win the argument. They control the pump. Explain briefly, offer an approved container, and if the customer refuses, do not authorize the pump or stop it. If the customer becomes aggressive, step back and follow the guidance in HSE-341: stay inside, do not argue, and call for help if needed.

For supervisors: make the safe way the easy way

Stock approved containers near the till at a fair price. Post the container rule at every pump with a simple picture of a can on the ground. Train cashiers on the intercom script for container problems. And log refusals; a pattern of the same customers or the same problem tells you where more signs or a conversation are needed.

Containers brought back to the station

Customers sometimes bring back containers that leak, have cracked spouts, or hold fuel they no longer want, such as old mixed gasoline for a two-stroke engine or fuel contaminated with water. Do not accept unwanted fuel into the station's tanks or garbage, and do not pour it down a drain. Tell the customer where their municipality accepts household hazardous waste. If a leaking container is left on the forecourt, treat it as a small spill: move it upright onto absorbent, away from the pumps and drains, wearing nitrile gloves, and arrange disposal through the company's procedure. Never put a fuel container, even an empty one, in the store's garbage compactor or cardboard baler, because the vapor left inside can ignite.

Containers also matter inside the store. Approved containers for sale should be stored empty, with caps on, and away from heat. Small engine fuel sold pre-mixed in cans, starter fluid, fuel line antifreeze and windshield washer fluid are flammable products and belong on shelving away from heaters and the coffee machine, in quantities the fire code allows for retail display. If a customer drops and breaks one inside the store, treat it as a spill, ventilate and keep ignition sources away until it is cleaned up.

For supervisors: check the container display

Once a month, look at the approved containers on sale. Are all sizes the station allows in stock, in all three fuel types? Are the labels and standard marks visible? Are any damaged, missing caps or faded from sitting in a sunny window? A customer who cannot buy the right container at the till is the customer most likely to argue for a milk jug at the pump.