Continued... POOL & SPA NEWS
NOVEMBER 20, 1996
"We need to approach this as a technical problem
and identify effective solutions that can be realistically implemented
in the field. And to do that, we've got to be working off the same
As Rowley noted in his briefing at the CPSC round
table, suction entrapment refers to four separate types of accidents:
hair entrapment, limb entrapment, body entrapment and disembowelment.
All such accidents occur when a bather becomes entrapped on a drain by
excessive suction power.
In the vast majority of cases, the culprit drain is
plumbed to a pump in such a way that it serves as the single suction
point for that pump. And in most cases, except those of hair
entrapment, the drain is also unprotected by a grate or anti-vortex
cover. The combination of these two conditions creates a dangerous
The CPSC has investigated 10 such incidents since
1980, nine of which occurred in commercial wading pools.
Each suction-entrapment accident is investigated in
terms of its physical description, which includes anecdotal information
about the circumstances surrounding the event — such as how it was
that the victim came into contact with the drain.
Accidents are also examined technically, with
investigators looking into issues such as pipe and pump size, and
reconstructing the event from an engineering perspective.
Once all the data is examined and a cause identified,
recommendations for the prevention of similar accidents are often
established and disseminated to the public.
According to Rowley, CPSC investigations coupled with
data gathered during the Swimquip study form the basis of some safety
recommendations that apply to wading pools, spas and swimming pools
nearly across the board.
These measures can be divided into three categories
design solutions, protective measures and warnings.
Of these, Rowley notes, the design solution is by far
the most reliable way to prevent suction-entrapment accidents.
"These are technical things that we can do to
eliminate risk altogether,' he explains. "Obviously, that's what
you want to try to achieve before you do anything else."
Noting that the vast majority of all
suction-entrapment cases involve a single-suction plumbing arrangement,
says Rowley, the primary design solution is to require dual suction
outlets for each and every pump installed on a wading pool, spa or
PERFECTING A STANDARD
The idea of requiring dual suction points for
commercial pools and spas is nothing new. Again, ANSI/NSPI standards
already include such language, as do many building codes in counties and
cities across the country.
Still, Rowley and others tackling the problem want to
improve on the dual-drain standard, and the new language drafted for
inclusion in the ANSI/NSPI standard tightens the definition of a safe
One of the most significant additions to the existing
standard is a requirement that, in the event that one drain is completely
blocked, the other should have a maximum flow rate of 6 feet per
second — a rate that would not generate deadly suction.
Another key improvement is a mandatory minimum
distance of 3 feet between drains, a measure designed to avoid the
possibility that one bather could possibly block two drains at the same
"This is the best way to prevent these
accidents," says Rowley. "And as far as new construction goes,
it's a very simple issue: No one should ever plumb a wading pool, a spa
or a swimming pool with a single suction point. When you're installing a
pool, for example, it's very easy and inexpensive to install a second
When looking at retrofits, says Rowley,
implementation can be a bit more complicated. To enforce a dual
suction-point mandate would require relatively expensive construction
work on large numbers of existing wading pools, spas and swimming pools.