10
Florida Pool Pro
sm
• July 2014
“Sump” thing is wrong
By Dan Johnson, Swim, Inc. /
The ANSI/APSP-7 standard for suction entrapment avoidance went into
effect here in Florida on March 1, 2009 as part of the 2007 Florida Building
Code. At that time, the five known entrapment hazards and three root causes
were not widely understood and there was much confusion among builders
and building officials about the various compliance requirements and options.
Over the years, we have learned, and become “comfortable” with the standard
and the entrapment protection methods/systems we choose to employ for
compliance.
But since that time, in several areas of the state, there is a compliance
problem that is being overlooked or going unnoticed. Some field built sumps
are being constructed in an unsafe configuration, creating a potential for hair
entrapment. Data gathered by the writing committee of theANSI/APSP-7 2006
standard indicated that, to that point in time, hair entrapment was the leading
cause of suction entrapment.
The ASME A112.19.8 standard for suction outlet fittings, included in the
ANSI/APSP-7 standard requires that the top of the suction pipe in field built
sumps be at least 1½ pipe diameters below the bottom of the cover and that
even the outside edges of the sump be at least one pipe diameter below the
cover. This means that if you use a 2-inch suction pipe, the top of the pipe
(whether horizontal or vertical) must be at least 3 inches below the bottom of the
cover. This requirement is designed to allow water to move through all areas
of the cover, thereby diffusing and diminishing the force created at the top of
the cover/grate. The closer to the bottom of the cover, the more focused the
area of suction becomes, resulting in higher, unsafe velocity directly above the
pipe. Try vacuuming your car’s floor mats holding the vacuum hose 3 inches
from the mat – not enough force to pick up dirt; move it within an inch and you
create a strong enough force to pick up dirt. That’s the same concept but in
reverse, you do want the force to pick up the dirt – you don’t want the force to
draw hair through the cover.
