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: 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