Pentair AUTOTROL MAGNUM 742 - Recommended Backwash Flow Rates for Various Media; Cycle Time Calculation

Installer Manual Magnum 742-762 - System sizing
Ref. MKT-IM-012 / C - 25.10.2019 31 / 106
4.1.3. Recommended backwash flow rates for various media
* 10°C water temperature, 50% bed expansion.
4.2. Cycle time calculation
All the Logix controller range automatically calculates the unit capacity as well as the cycle time.
No calculations are therefore required.
Media
Tank diameter
14"
(35.6 cm)
Tank
16"
(40.6 cm)
Tank
18"
(45.7 cm)
Tank
21"
(53.3 cm)
Tank
24"
(61.0 cm)
Tank
30"
(76.2 cm)
Tank
36"
(91.4 cm)
Tank
Drain line flow control [gpm]
* Softening Resin
(5.0 gpm/ft
2
)
(12.25 m/h/cm
2
)
5 7 9 12 15 25 35
* Fine Mesh
Softening resin
(2.8 gpm/ft
2
)
(6.86 m/h/cm
2
)
3 4 5 7 9 14 20
Multi Layer
(15 gpm/ft
2
)
(36.75 m/h/cm
2
)
15 20 25 36 50 70 105
Birm, Greensand,
Carbon
(10 gpm/ft
2
)
(24.5 m/h/cm
2
)
10 15 17 25 30 50 70