5
Outlets Per Pump
Provide at least two hydraulically balanced main drains, with covers (see
above), for each swimming pool pump suction line. The centers of the main
drains (suction fittings) must be at least three feet apart.
The system must be built so that it cannot operate with the pump drawing
water from only
one
main drain (that is, there must be at least two main drains
connected to the pump whenever it is running). (See Figure 1). However, if
two main drains run into a single suction line, the single suction line may be
equipped with a valve which will shutoff
both
main drains from the pump
(see Figure 1).
More than one pump can be connected to a single suction line as long as the
requirements above are met.
Water Velocity
If 100% of the pump’s flow comes from the main drain system, the maximum
water velocity in the pump suction hydraulic system must be seven feet per
second or less even if one main drain (suction fitting) is completely blocked.
The flow through the remaining main drain(s) must comply with the latest
ASME/ANSI Specification for
Suction Fittings For Use in Swimming Pools,
Spas, Hot Tubs, and Whirlpool Bathtub Applications.
Piping – General
System piping must be at least equal to size of pump connections.
To prevent strain on the pump casing and foundation, pipe and fittings must
be aligned to pump without forcing.
To avoid strains on the pump, support both suction and discharge pipes
independently. Place these supports near the pump.
To avoid a strain left by a gap at the last connection, start all piping at the
pump and run pipe
away
from the pump.
At Least
3 Feet
Main Drain
Main Drain
Anti-entrapment
Cover, screw-fastened
to Main Drain Sump
Anti-entrapment
Cover, screw-fastened
to Main Drain Sump
Pump
Valves OK between
pump and Tee
No valves between
Tee and Main Drains
2515 0497
Figure 1 – Recommended pump suction layout.
