DCHAS-L Discussion List Archive
Date: Wed, 10 Sep 2008 15:30:28 -0400
Reply-To: List Moderator <ecgrants**At_Symbol_Here**UVM.EDU>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: List Moderator <ecgrants**At_Symbol_Here**UVM.EDU>
Subject: Re: Anyone familiar with gas station pump hazards?
A reply to a question from last week...
>I had a phone call from someone who was injured at a self-service
gas pump in rural Georgia.
From: sstepenuck**At_Symbol_Here**ne.rr.com
Subject: Anyone familiar with...
Date: September 9, 2008 5:18:15 PM EDT (CA)
I forwarded that email to my kids and to one of my cousins who has
much experience in industry.
Here, with a couple of minor grammatical mistakes corrected, and with
full disclaimers on my and his part, is his reply:
I do suspect urban legend here or at least some incorrect facts. I've
worked around fuel dispensing equipment all my life and never heard of
such a thing.
Most modern fuel pumps aren't really pumps, they=92re only metering
dispensers because the actual pump is in the underground tank. So for
technical accuracy, I will use the word "dispenser" as opposed to
"pump" even though we all know them as pumps.
Most modern dispensers have an overhead manifold with a hose
attachment fitting sticking through an opening in the overhead sheet
metal. =46rom that fitting hangs a very short piece of hose which ends
with a "break-away" coupler. =46rom the break-away coupler there is
usually the longer hose with nozzle.
The purpose of the break-away coupler is for the nitwit who drives
away with the nozzle still in the car. The break-away is designed to
be the weakest link in the hose assembly so that it will part first
when faced with the tension created by a departing car. Even so, it
takes a fair amount of force to cause a break away. Most people could
not part one simply by yanking because they are not strong enough. The
break-away has an internal valve which will slam shut in the event it
is parted. They are quite reliable and are rigorously tested and they
immediately stop all fuel flow. There might be a momentary "psst" of
fuel but no great wide-open spraying like you might have with a garden
hose nozzle. They are similar in design to quick-disconnect couplers
used on pneumatic tools.
Even if the valve failed and caused the short hose with the break-away
to whip around wildly, keep in mind that length is very short and the
height is well above any normal person's head. Also most systems
operate a much lower pressures that claimed in the e-mail.
Consider this: Everybody has played with a garden hose. The average
garden hose operates at typical water main pressure of 35 to 80 PSI
and even at that pressure the hose would blow itself out of the filler
pipe if you weren't forcibly holding it in. Imagine a fuel nozzle at
150 PSI! It would take at least two rugged firefighters simply to hold
the nozzle into the filler on your fender. That vision alone puts the
lie to this story. If you stuck a 150 psi nozzle into an empty "jerry
jug" setting on the ground and pulled the trigger, the jug would be
blown clean across the parking lot assuming you weren't knocked to the
ground by the reactive thrust.
I suppose there is the possibility that a break-away coupler could
just spontaneously part and the hose would fall to the ground. If you
were standing directly under it you might be hit in the head but it
would be by the force due to gravity because the pump pressure would
be contained in the short portion still attached to the dispenser. It
would seem to me that only two scenarios that could cause a
spontaneous break-away are an incorrectly installed break-away coupler
that wasn't tested, i.e. the two haves weren't fully inserted together
and latched or a damaged break-away coupler that just experienced an
incomplete break-away caused by a departing nitwit. Keep in mind that
the second scenario would require the next customer to have to pick up
the nozzle from the ground because that's where it would be laying
since the nitwit drove away.
Unless I'm missing something here, I just can't buy this story as it's
written. I'm not writing it off entirely but it needs much more
detailed specifics. One thing is for sure, they aren't commonplace as
suggested in the e-mail. Also OSHA would cover any event at a full-
serve station where the operator is an employee. This would also be
true at non-public fleet fueling station. Even at the public self-
serve stations, any event that occurred while the employees were
servicing or testing the coupler would be covered by OSHA.
Mark
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