Installation Sheet

7034000M Copyright © Liberty Pumps, Inc. 2019 All rights reserved. 9 | EN
Duplex (Two Pump) Systems
Figure 4. Typical Duplex System Installation (variations may apply)
1. Place both pumps in basin, making certain the mounting
interface (i.e., guide rail, torque stop) is engaged correctly.
The duplex control used will include 3 or 4 floats that will
either be tethered to one of the discharge pipes or to an
independent rod or bracket. Follow the duplex control
manufacturer’s instructions provided with the device. Each
float switch must have adequate clearance to side wall of
basin and free, unobstructed movement throughout its
complete travel and must not contact the pump, piping, or
other objects. Minimum pump turn OFF level must not be set
below Table 1 values.
2. Connect an individual discharge pipe to each pump. Do not
reduce the discharge to below that which is provided on the
pump. Sewage pumps should not be smaller than 2". Larger
pipe sizes may be required in some applications to reduce
friction head loss over long runs. Contact Liberty Pumps or
other qualified person if there are questions regarding proper
pipe size and flow rates.
3. A check valve on each discharge line, prior to tying into one
common line, is necessary to prevent the recycling of fluid
from one pump to the other. Depending on the basin height,
the check valves may either be inside or outside the basin. To
install inside basin, install check valve on each discharge pipe
now. To install outside basin, install in Step 6.
4. Mount and seal the basin cover.
5. Install unions or flexible connectors just above the cover on
each discharge to facilitate pump removal when necessary.
6. Install check valves on each discharge after the union and
prior to the gate valve to prevent backflow.
7. Install a gate valve after the check valve to allow for periodic
cleaning of the check valve and removal of pumps.
8. The remainder of the discharge line should be as short as
possible with a minimum number of turns to minimize friction
head loss. Larger pipe sizes may be required to eliminate
friction head loss over long runs.
9. Vent basin in accordance with applicable plumbing codes.
Operation
Starting System
1. Verify all plumbing components are installed correctly and
functional. Verify all valves are open and ready for pump use.
2. Double check all wire connections. Re-tighten all factory and
field connections.
3. Ensure pump has no obstructions.
4. With all electrical and mechanical connections complete and
secure, turn on power to pump and control panel, if
applicable.
5. Verify operation of the pump, floats, and alarm circuits.
6. Run several cycles of water through the system to verify
correct control operation for the installation.
Be certain to complete adequate testing, especially on systems
with multiple pumps or custom control configurations.
Maintenance and Troubleshooting
 Accidental contact with electrically live parts, items, fluid, or
water can cause serious injury or death.
 Always disconnect pump(s) from power source(s) before
handling or making any adjustments to either the pump(s),
the pump system, or the control panel.
 Wear adequate Personal Protective Equipment when working
on pumps or piping that have been exposed to wastewater.
Sump and sewage pumps often handle materials that can
transmit illness or disease upon contact with skin and other
tissues.
 Do not enter a pump basin after it has been used. Sewage
and effluent can emit several gases that are poisonous.
 Verify correct 3-phase pump rotation before retuning to
service.
Pump #1
Pump #2
Control Floats
Discharge
Vent
Unions
Inlet
Gate Valve Gate Valve
Check Valves
Leads to
Control
Panel
Tee
RISK OF ELECTRIC SHOCK
RISK OF SERIOUS INJURY OR DEATH