The flow rating for pools with multiple, blockable SOFAs piped together in one body of water without isolation
valves shall be determined by combining the flow rating of all SOFAs, minus the flow rating of one. If the flow
ratings of all SOFAs are not equal, subtract the flow rating of the SOFA with the highest flow rating.
The flow rating for existing pools with a single, blockable SOFA is the flow rating of the SOFA, when also installed
in conjunction with an additional device or system designed to prevent suction entrapment, where the additional
device or systems is of a type listed in section 9.4 of ANSI/APSP/ICC-16-2017. A single, blockable SOFA in a
system that does not also include one of the additional devices or systems shall result in a flow rating of zero.
Description
Max System Flow
Floor
Max System Flow
Wall
Min Flow Rating of Each
Cover % Max System
Flow Rate
*One SDX2 High Flow Safety Drain
180 gpm (681 lpm)
140 gpm (529 lpm)
100%
Two SDX2 High Flow Safety Drains
180 gpm (681 lpm)
140 gpm (529 lpm)
100%
Three SDX2 High Flow Safety Drains
360 gpm (1362 lpm) 210 gpm (795 lpm)
66.7%
Four SDX2 High Flow Safety Drains
360 gpm (1362 lpm) 280 gpm (1060 lpm)
50%
*The addition of an approved SVRS is required when a single SDX2 is being used. Table derived from ANSI/APSP-7 Section
4.6 Table 1. System flow based on 3" side outlet floor plumbing configuration chart on page 6.
Pipe size. To design an efficient suc-
tion system in accordance with national
swimming pool standards, the following
pipe sizing guideline should be followed:
Suction Pipe Size
Max Residential GPM
Max Public GPM
1.5"
50
37
2"
82
62
2.5"
117
88
3"
180
136
Flow vs Head Loss
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
40
50
60
70
80
90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250
Flow (GPM)
Head Loss (inHg)
USE ONLY PARAMOUNT GENUINE REPLACEMENT PARTS
7
USE ONLY PARAMOUNT GENUINE REPLACEMENT PARTS
