NFPA Journal - November/December 2020 - 58

A firefighter was killed and four people were critically
injured in a gas explosion in Farmington, Maine, in
September 2019. The blast also destroyed nearby
mobile homes, leaving 31 people homeless.
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a document like NFPA 715 to be developed. The technical committee will meet
virtually until the coronavirus pandemic
eases, Olenick said, and the standard is
slated for release in June 2022.
Before the NFPA 715 technical committee could begin writing the standard,
however, it needed research showing
how gases like natural gas and propane
disperse and where detectors should
ideally be installed based on that dispersion. That's where the Fire Protection
Research Foundation stepped in.
The foundation's work culminated
in August with the release of a study
titled "Combustible Gas Dispersion in
Residential Occupancies and Detector
Location Analysis," the findings of which
will heavily inform the new standard.
The study found that, in general, detectors aren't as effective when placed near
HVAC equipment, door gaps, stairwells,
or other areas where there are openings
or airflow. For natural gas, detectors
worked best when placed closer to
the ceiling, while for propane, they
worked best when placed closer to the
floor-this made sense to researchers, as
natural gas vapors are lighter than air
and propane vapors are heavier.
Scott Davis, one of the authors of the

study and CEO of the Maryland-based
fire and explosion safety consulting
agency Gexcon US, said the report represents "a very good first step" in the
standardization process.
"We looked at numerous leak conditions and leak rates for numerous
structural configurations to create
what I would call a performance-based
study," he said. "And we're doing this
before we actually start putting these
detectors up. So this is a huge piece of
work toward getting the optimal detector location such that you detect the
condition prior to the hazard."
Thomas said a standard like NFPA
715 could have made a difference in the
Maine incident. "If that building had
included detectors that were compliant
with what 715 is going to detail, you
would've had a detector reacting to the
[concentration] of the gas and not the
mercaptan," he said. "In circumstances
where humans aren't able to detect the
gas, those detectors could have provided an earlier warning."
In other situations, like the 2018 Merrimack Valley incident, it's less clear how
much impact detectors might have had.
"It was such a rapid over-pressurization,
I don't think detectors would've made

a difference for some of those properties," said Brian Moriarty, fire chief in
Lawrence, Massachusetts, one of the
cities hit by the gas-related fires and
explosions. "In other properties, though,
where we didn't necessarily have a fire
or explosion but the home still filled
with gas, detectors could've been a great
enhancement to life safety."
A parting piece of advice Moriarty
shared was to not overlook human
behavior and the need for public education when writing the new standard. "We
see with smoke alarms that people don't
necessarily evacuate when alarms sound,
that they'll take out the batteries," he
said. "I think you have to have an audible
instruction that says get out of the house,
don't use any appliances or devices, and
call 911 from outside the building."
Olenick agreed that public education
will be key to the long-term success of
NFPA 715. "We're going to need to do
more than just say, 'Put this alarm in and
do it this way,'" he said. "Firefighters and
safety professionals will have to say, 'Hey,
when it does sound, these are the steps
you should take.' It's a team effort."
ANGELO VERZONI is a staff writer for
NFPA Journal.

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