Franklin Electric MONODRIVE UTILITY UT3W, Owner'S Manual

Page: 13 / 128

INSTALLATION AND SETUP
Installation Process
13
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 MonoDrive Utility to a conventional system with an existing large
tank, refer to
“Tank Size and Bump Mode Adjustments” on page 26 .
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
Minimum Supply Pipe Sizes
The minimum supply pipe inside diameter past the pressure sensor (transducer) should be
selected to not 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 up to 1 HP Minimum Tank Size over 1 HP
Less than 12 gpm (45.4 lpm) 2 gallons (7.6 liters) 4 gallons (15.1 liters)
12 gpm (45.4 lpm) and higher 4 gallons (15.1 liters) 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”