AIM Manual
Motor Application » All Motors (Page 6)
Well- Large Diameter, Uncased, Top Feeding, Screens
Franklin Electric submersible motors are designed to operate with a cooling flow of water over and around the full length of the motor.
If the pump installation does not provide the minimum flow shown in Table 6, a flow inducer sleeve (flow sleeve) must be used. The conditions requiring a flow sleeve are:
• Well diameter is too large to meet Table 6 flow requirements
• Pump is in an open body of water
• Pump is in a rock well or below the well casing
• The well is “top-feeding” (a.k.a. cascading)
• Pump is set in or below screens or perforations
Water Temperature and Flow
Franklin Electric’s standard submersible motors, except Hi-Temp designs (see note below), are designed to operate up to maximum service factor horsepower in water up to 86 °F (30 °C). A flow of 0.25 ft/s for 4" motors rated 3 hp and higher, and 0.5 ft/s for 6" and 8" motors is required for proper cooling. Table 6 shows minimum flow rates, in gpm, for various well diameters and motor sizes.
If a standard motor is operated in water over 86 °F (30 °C), water flow past the motor must be increased to maintain safe motor operating temperatures. See HOT WATER APPLICATIONS on page 7.
NOTE: Small 4” Motors (2Hp & Smaller) = no minimum flow required, except flow must be greater than zero flow.
NOTE: Franklin Electric offers a line of Hi-Temp motors designed to operate in water at higher temperatures or lower flow conditions. Consult factory for details.
Table 6 Required Cooling Flow
| MINIMUM GPM REQUIRED FOR COOLING IN WATER UP TO 86 °F (30 °C) | |||
| CASING OR SLEEVE ID INCHES (MM) | 4" MOTOR (3-10 HP) 0.25 FT/S GPM (L/M) | 6" MOTOR 0.50 FT/S GPM (L/M) | 8" MOTOR 0.50 FT/S GPM (L/M) |
| 4 (102) | 1.2 (4.5) | - | - |
| 5 (127) | 7 (26.5) | - | - |
| 6 (152) | 13 (49) | 9 (34) | - |
| 7 (178) | 20 (76) | 25 (95) | - |
| 8 (203) | 30 (114) | 45 (170) | 10 (40) |
| 10 (254) | 50 (189) | 90 (340) | 55 (210) |
| 12 (305) | 80 (303) | 140 (530) | 110 (420) |
| 14 (356) | 110 (416) | 200 (760) | 170 (645) |
| 16 (406) | 150 (568) | 280 (1060) | 245 (930) |
- 0.25 ft/s = 7.62 cm/sec 0.50 ft/s = 15.24 cm/sec 1 inch = 2.54 cm
Flow Inducer Sleeve
If the flow rate is less than specified, then a flow inducer sleeve must be used. A flow sleeve is always required in an open body of water. FIG. 1 shows a typical flow inducer sleeve construction.
EXAMPLE: A 6" motor and pump that delivers 60 gpm will be installed
in a 10" well.
From Table 6, 90 gpm would be required to maintain proper
cooling. In this case adding an 8" or smaller flow sleeve provides the
required cooling.
FIG. 1
