improving pool safety
A tragedy inspired the design of a drain cover to prevent drownings and injuries.
By Michael Valenti, Senior Editor
In May 1996, at the Atlantic Club in Manasquan,
N.J., a 16-year-old girl swimming in the club's pool became vacuum sealed
against the foot-square grating covering the main drain. Despite the efforts
of two police officers, three certified pool officials, and her boyfriend,
the teenager perished because a one-ton pressure vacuum, formed by her
body against the drain, held her beneath the surface.
Attorneys for the Atlantic Club approached Triodyne Inc. of Niles, Ill.,
to serve as expert witness during the litigation following the tragedy.
Triodyne is a mechanical engineering firm whose business includes designing
and manufacturing industrial safety devices. That forensic service inspired
Triodyne to develop the Anti-Hair Snare Plus drain cover to prevent such
tragedies in the future. Triodyne's work on the device was described in
a paper presented at ASME's International Mechanical Engineering Congress
and Exposition in New York in November.
The Anti-Hair Snare Plus was designed and marketed by Triodyne Safety
Systems LLC. The company is a subsidiary formed in 1998 to solve safety
problems Triodyne encounters in four areas, including pools and spas.
Triodyne Safety Systems first investigated the hazards involved. The Consumer
Product Safety Commission informed Triodyne's researchers that body sealing
incidents in pools, spas, and hot tubs occurred as frequently as three
times a month in the United States.
"More ghastly than drowning, in some cases when the buttocks became
sealed and the vacuum was strong enough, victims became eviscerated,"
said Peter J. Poczynok, an ASME member and senior mechanical engineer
at Triodyne Inc. Poczynok is also president of Triodyne Safety Systems.
A more common pool hazard than body sealing, according to the CPSC, was
that of hair entering a drain and becoming entangled in the elements.
Triodyne Safety Systems also interviewed pool industry members and reviewed
international literature. Those sources reported cases in which children
playing with drain openings had trapped their fingers. Even when drain
cover holes were small enough to prevent this, pranksters tearing the
drain covers off openings increased the risk of injury to others.
In addition, months of sunny exposure in places like Florida degraded
acrylontirile-butadiene-styrene, or ABS, drain covers, causing them to
break.
"We approached NSF International of Ann Arbor, Mich., to develop
the material specifications for our new pool cover, as well as for third-party
laboratory certification of the product," said Poczynok. This independent,
nonprofit organization provides third-party assessment of standard conformity
of various technologies and products, particularly those that serve in
the food, water, indoor air quality, and environmental industries.
Triodyne
equipped its pool cover with cantilevered grading elements designed to
shed hair, and eliminated the flat cover to prevent body sealing.
The design team determined that the new anti-snare drain cover would
have to be compatible with pool cleaners, possess a frame that allowed
it to be bolted on, be available in a variety of colors, and create minimal
vortex. Because residential pools with 6- or 8-inch round drains on the
bottom are the most prevalent, Triodyne designed its first-generation
safety drain covers to suit them.
"To address hair entanglement, we designed cantilevered grading elements,
so that hair entering the drain could escape at the end of the element.
We found that elements possessing a greater than 45-degree angle will
shed hair, whether it is knotted or wrapped around the element,"
explained Poczynok. Triodyne said the 50-degree angle in its drain cover
elements ensures that they will shed hair.
The other major advantage of cantilevered grading elements is that they
eliminated the conventional flat cover to prevent body sealing. To prove
this, Triodyne mounted a prototype anti-snare cover on an acrylic panel,
and a conventional square pool drain cover on another panel. "We
then inflated balloons over each opening to prove the anti-hair snare
cover would not provide a body seal," said Poczynok.
Triodyne machined 8-millimeter holes in its cover, too tiny for the smallest
child's finger to fit into, and used stainless steel screws flush with
the cover surface to prevent friction grip. The company made its covers
of polyvinyl chloride, which is more resistant to solar degradation than
the ABS commonly used.
The Anti-Hair Snare Plus does cost more than its conventional counterparts—$39.95
manufacturer suggested retail price compared with $12—but safety
concerns have helped sell more than 5,000 of the covers during its maiden
year, according to Poczynok, through national pool part distributors,
including Horner Equipment of Florida Inc., in Fort Lauderdale.
"The State of Florida is actively developing a new building code
for pools and spas that will set standards for safety issues, like those
addressed by the Anti-Hair Snare Plus," noted Poczynok. "Although
they started out strict, as often happens, the standards are becoming
watered down as the industry lobbies legislators. We hope the final version
will set strong safety standards."
The next step for Triodyne Safety is developing versions of the Anti-Hair
Snare Plus to fit the 12-inch and 18-inch square drain covers that are
mounted on the bottoms of commercial pools, as well as side-mounted drains
on both residential and commercial pools and spas.
They Can Look It Up
Triodyne Inc.'s safety research does not stop at the water's edge. Its
Vehicle and Mobile Equipment Engineering Center provides consulting and
research service on safety and design investigations for recreational,
commercial, and off-road vehicles and equipment. This encompasses research
into accidents such as jackknifing, rollovers, collisions, and fires,
as well as seat belt, visibility, and handling issues. The center also
studies accidents by performing computer simulation, interpreting tire
skid marks, and taking aerial photographs of accident sites. The center
tests vehicles on tilt tables and on test tracks.
Another branch of Triodyne is its Safety Information Center, which the
company claims is one of the largest safety libraries in the world. Triodyne
offers customized research, online database searches, document delivery,
and telephone surveys. Because of their extensive experience in a wide
variety of areas, the safety librarians are able to tackle diverse projects.
Among the questions they have answered are: how to make artificial snow,
what ergonomic forces act upon the human body while a person uses a leg
exerciser, how many seconds does the bell on a train sound before it reaches
an intersection, what are the requirements to retrofit an agricultural
cultivator made in the late 1970s, what is the available data on lead
poisoning in children, and what are the industry standards for lateral
paper files.
Triodyne offers Bibcat 2500 gratis. This is a subject listing of all the
safety bibliographies compiled by the Safety Information Center.