2399000D
Copyright © Liberty Pumps, Inc. 2020 All rights reserved.
5 | EN
Pump Design
PRG-Series grinder pumps are designed for continuous under-
water operation. The motor and pump form a close-coupled,
watertight unit. The induction motor is insulated against heat and
moisture in accordance with Class B 265°F (130°C) regulations.
The motor is protected against damage from water entry by a
mechanical type cartridge seal with two silicon carbide faces.
The impeller and volute are designed for efficient flow
characteristics and clog-free operation. The hardened cutters
grind solids and fibrous matter into small particles that can be
safely pumped through small diameter piping.
For added protection, consider the addition of a Liberty Pumps
back-up pump, as well as a high water level alarm in applications
where loss of pump function could result in property damage. If
an alarm is used, it must be connected to a separate electrical
circuit. A duplex pumping system is recommended for critical
installations.
Pump System Components
Control Panel
Manual PRG-Series pumps (“
M
” suffix) require a separate,
approved pump control device or panel for automatic operation.
Operation will be according to the control selected. Refer to
separate manufacturer’s instructions supplied with the unit. Verify
the electrical specifications for the control panel properly match
those of the pump.
Mounting, installation, and wiring connections are specific to the
control panel used. Refer to the manufacturer’s instructions
supplied with the unit.
IMPORTANT:
When connecting a PRG-Series pump to an existing
control panel, verify the panel is correctly sized and equipped for
the pump.
Control panels designed for use with the PRG-Series pumps
available from Liberty Pumps can be found at http://
www.LibertyPumps.com/Portals/0/Files/panel_selection_guide.pdf
Thermostat
A thermal overload (thermostat) is integrally mounted to the
motor and wired to shut down the pump if overheating occurs.
The thermostat resets automatically after the pump has cooled.
Float Switches
Single-phase 208/230V pumps shall only be operated without
the float switch by using the circuit breaker or panel
disconnect.
Automatic Models
Automatic models
(“
A
” suffix) come factory-equipped with a float
switch mounted to the pump. These models come with two
cords—one to the float switch and the other to the pump motor.
The float switch cord has a series (piggyback) plug enabling the
pump motor cord to be plugged into the back of it. The purpose
of this design is to allow temporary manual operation of the
pump. On/Off operation of the pump must be controlled by the
circuit breaker. For manual operation, refer to
In the event of switch failure, the pump cord can be separated and
plugged into the electrical outlet, directly bypassing the switch.
Pumps should only be operated without the float switch by using
the circuit breaker or panel disconnect.
The turn ON level of automatic models is approximately 12” to 16”
above the bottom of the basin. The turn OFF level is
approximately 6” above the bottom of the basin. Other pumping
differentials may be obtained by tethering the switch cord to the
discharge pipe.
Note:
A minimum cord length of 3-1/2” from the
tether point to the top surface of the float is required for proper
switch operation. If using a differential other than the factory
setting, verify the pump shuts off with at least 6” of fluid left in the
basin so the impeller remains submerged.
Vertical switch models
have pumping differentials pre-set by a
rubber stopper placed on the float rod. To reset the pumping
differential, slide the stopper to the required height to set the off
position. This height Is approximately 2” from the bottom of the
float rod, or high enough that the float does not have the
potential to hang up on the pump or discharge.
Switchless (Manual) Models
Manual pumps that have been factory constructed with a
power cord with no male attachment plug must use an
approved motor control panel. Do not wire a switch in series
with the pump power cord as this can overload the wires.
Overloaded wires get very hot and can catch on fire.
Manual pumps
(“
M
” suffix) with no switch are intended to be run
using an approved liquid level control or approved motor control
with correct rating that matches motor input in full load amperes.
If the pump(s) are to be operated by either a simplex or duplex
control panel, or other optional control device, follow the
manufacturer’s instructions provided with the control panel for
power connections.
RISK OF ELECTRIC SHOCK
RISK OF FIRE
