Suction Outlets Per Pump
Provide at least two hydraulically balanced main drains, with covers (see
Page 5), as suction outlets for each circulating pump suction line. The cen-
ters of the main drains (suction outlets) on any one line 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 2).
However, if two main drains run into a single suction line, the single suction
line may be equipped with a valve which will shut off
both main drains
from the pump (see Figure 2).
More than one pump can be connected to a single suction line as long as
the requirements above are met.
Water Velocity
The maximum water velocity through the suction fitting or cover for any
suction outlet must be 1.5 feet per second unless the outlet and cover com-
ply with the latest ASME/ANSI Specification for
Suction Fittings For Use in
Swimming Pools, Spas, Hot Tubs, and Whirlpool Bathtub Applications. In
any case, do not exceed the suction fitting’s maximum designed flow rate.
If 100% of the pump’s flow comes from the main drain system, the maxi-
mum water velocity in the pump suction hydraulic system must be six feet
per second or less even if one main drain (suction outlet) 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.
Testing and Certification
Suction outlet covers must have been tested by a nationally recognized testing
laboratory and found to comply with the latest ASME/ANSI Specification for
Suction Fittings For Use in Swimming Pools, Spas, Hot Tubs, and Whirlpool
Bathtub Applications.
Fittings:
Fittings restrict flow; for best efficiency use fewest possible fittings (but at
least two suction outlets).
Avoid fittings which could cause an air trap.
Pool fittings must conform to International Association of Plumbing and
Mechanical Officials (IAPMO) standards.
Use only non-entrapping suction fittings or double suction.
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