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Starts & Stops

Gas cap for hands-free fueling? Not so fast

Using a gas cap to hold nozzles open at the pump could increase the risk of dangerous spillovers.

John Blanding/Globe Staff

Using a gas cap to hold nozzles open at the pump could increase the risk of dangerous spillovers.

When you wake up in the morning and your iPhone weather app tells you that it “feels like” -11 degrees Fahrenheit, survival mode kicks in — even at the gas pump.

Most drivers have probably noticed that almost all gas stations in the state are missing fuel nozzle trigger locks, officially known as “hold-open clips.” Those clips allow fuel to flow freely into the vehicle’s tank without the need for human operation, automatically shutting off once the tank is full. Without the clips, winter-weather drivers must stand out in the cold, clenching the nozzle while they attempt to control their teeth-chattering.

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But some Massachusetts drivers have found a sneaky solution, one you may have seen at your local gas station: They jam the car’s gas cap underneath the trigger, keeping the nozzle pumping while they take refuge in the driver’s seat, protected from the single-digit temperatures and comfortably listening to Terry Gross or Tupac, according to their particular FM-radio proclivities.

I had always assumed that the lack of gas clips in Massachusetts could be attributed to austere New England sensibilities, a product of the region’s aversion to comfort and predilection for hardship — the same reason why residents disdain home air-conditioning and why the seats at Fenway are so uncomfortable. Staying cozy in the driver’s seat while the hold-open clip does all the work is a move for softies, very un-Massachusettsian.

But the absence of hold-open clips on gas nozzles is actually part of a decades-old law — one that was passed to prevent gas station fires that can be caused by static electricity. The idea was that sliding in and out of the seat of your car could create static friction, and that the shock of touching the nozzle could ignite fuel vapors emitted by the nozzle. (And it does indeed happen, though it’s rare. There’s a video on YouTube that’s pretty terrifying.)

Better to keep people standing with their hand on the nozzle, politicians thought. New York is the only other place with a statewide ban against the latches.

But some motorists have probably been using the whole gas-cap-in-the-nozzle trick for years. And others have discovered it through the growing popularity of “Life Hack” lists — compilations of those simple, why-didn’t-I-think-of-that fixes to some of life’s enduring problems that go viral on social media. Use duct tape to pull open stuck jar lid, they say. Clean the gunk from between the keys of a desktop keyboard with the sticky part of a Post-it note. And the gas cap, they say, is the perfect shortcut for hands-free fueling.

Bad idea, said Robert N. Renkes, executive vice president and general counsel for the Petroleum Equipment Institute, a trade association for people involved in handling petroleum.

The funny thing is, the risk of static fires has largely been eliminated. Almost all new cars come with a mechanism in the gas tank that filters vapors, collecting them inside the car to be burned as the vehicle runs. So,unless you have an old car, using your gas cap as a trigger lock doesn’t stand much of a chance causing an explosion.

“The number of static fires we have had with people getting into their cars have been significantly reduced,” Renkes said.

Still, he said, if you go inside your car while fueling, it’s a good idea to touch the handle on your car door before you grab the nozzle to preemptively dissipate any potential static shock, just to be on the safe side.

But the danger of the gas cap fix, Renkes said, comes from the risk of a fuel spillover. The hold-open clips snap shut once the tank is full. But a jammed gas cap stays in place, even if the tank is full — and though the nozzle should automatically turn off the flow of gas anyway once the tank is full, it’s possible that the fuel sensor may fail. If the gas cap keeps holding open the trigger, the gas will keep pumping, possibly until it spills over onto the side of the car and pools on the ground, Renkes said.

“If you put a wallet in there, or put a gas cap in there, it may prohibit the latch from actuating. Then you’ll have an overflow,” Renkes said.

So, in essence: The law that was passed to lower the risk for drivers has now encouraged a behavior that is much riskier.

“We’d rather have a motorist stand there in full control of the nozzle. It’s when people start getting innovative that you have problems,” Renkes said.

Things go bump in the night

As we enter week two of the Callahan Tunnel closure, the project’s contractor, McCourt Construction, has established a 24-hour hotline for residents to call with complaints about construction-related noises or vibrations. The company has promised that all the loud work will take place between 7 a.m. and 10 p.m., but if there are any issues, the phone number is 617-908-2614.

Martine Powers can be reached at martine.powers@globe.com. Follow her on Twitter @martinepowers.
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