Franklin Electric SUBDRIVE UTILITY, Owner'S Manual

Page: 15 / 132

INSTALLATION AND SETUP
Installation Process
15
Minimum Pressure Tank and Supply Pipe Sizing
A VFD system needs only a small pressure tank to maintain constant pressure, although a larger
tank may be used. If adding a SubDrive Utility to a conventional system with an existing large tank,
refer to
“Tank Size and Bump Mode Adjustments” on page 28 .
The pressure tank pre-charge setting should be 70% of the targeted system pressure. To check the
tank’s pre-charge, de-pressurize the water system by opening a tap with the drive off. Measure
with a pressure gauge at the inflation valve and make any necessary adjustments.
Refer to the following recommendations for best performance.
Submersible Pump Applications with Franklin Electric 2-Wire Motor
A minimum tank size of 20 gallons is recommended. This is to ensure water is available during the
minimum off time of the motor. If a smaller tank is used, the tank may empty if a large water
demand immediately follows a motor off cycle.
Submersible Pump Applications with PSC Motor
Surface Pump Applications
Minimum Supply Pipe Sizes
The minimum supply pipe inside diameter past the pressure sensor (transducer) should be
selected not to exceed a maximum velocity of 8 feet per second (2.4 m/s) based on the flow rate of
the system.
Pump Flow Rating Minimum Tank Size
Less than 12 gpm (45.4 lpm) 2 gallons (7.6 liters)
12 gpm (45.4 lpm) and higher 4 gallons (15.1 liters)
Maximum Pump Flow Minimum Tank Size
10 GPM 2 gallons (7.6 liters)
20 GPM 4 gallons (15.1 liters)
30 GPM
6
gallons (22.7 liters)
40 GPM 8 gallons (30.3 liters)
Maximum GPM (lpm) Minimum Pipe Diameter
11.0 (41.6) 3/4”
19.6 (74.2)
1”
30.6 (115.8) 1-1/4”
44.1 (166.9) 1-1/2”
78.3 (296.4) 2”
176.3 (667.4) 2-1/2”