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2.4
Operating the Duplex Filter:
2.4.1 Valves upstream and downstream of the Duplex Filter should be opened and closed slowly to prevent water hammer on the Duplex Filter.
Open and close valves upstream and downstream of the Hayward FLV Series GFPP Duplex Filter, and the tandem lateral three-
way diverter valve on the Duplex Filter, slowly. Rapid increases in pressure or flow can create excess water hammer effect,
2.4.2 When switching flow through the Duplex Filter from one vessel to the other, operate the "T"-handle of the tandem lateral three-way
diverter valves slowly to avoid the generation of pressure spikes or water hammer effect on the vessels and the valve manifold. (See
Section 2.1)
2.4.3 Flow can be switched, or diverted, from one vessel to the other on the Hayward FLV Series GFPP Duplex Filter while flow is active and
while the unit is under pressure. Extreme caution must be used when performing this operation!! Read and understand all
instructions and warnings prior to operating the tandem lateral three-way diverter valve to switch flow from one vessel to the
other.
2.4.4 Routine maintenance, such as changing an o-ring, or a filter bag, can be performed on the vessel that is "offline" (i.e. flow has been
diverted to the other vessel), while flow through the vessel that is "online" is active and the "online" vessel is under pressure. Extreme
caution must be used prior to attempting to perform any maintenance on the "offline" vessel while the "online" vessel is still
under pressure and active flow!!
2.4.4.2 Before attempting any maintenance on the "offline" vessel, check to make sure that the "offline" vessel has been
isolated from flow and pressure by:
2.4.4.2.1 Checking the position of the arrow on the "T"-handle of the diverter valve to make sure it is pointing away
2.4.4.2.2 Opening the vent valve on the "offline" vessel.
2.4.4.2.3 Checking any pressure gauges which may have been installed on the cover of the "offline" vessel to
2.4.4.3 If the arrow on the "T"-handle is not pointing away from the "offline" vessel, STOP, and adjust the handle so that the
arrow is pointing directly at the active, or "online" vessel.
2.4.4.4 If the vent valve is opened on the "offline" vessel and fluid initially flows from the vent valve and then stops, this is an
indication that the vessel has been depressurized and is isolated from flow.
2.4.4.5 If the vent valve is opened on the "offline" vessel and fluid initially flows from the vent valve and then continues to flow
from the vent valve, STOP, as this is an indication that the "offline" vessel is still under pressure and active flow.
2.4.4.6 Refer to Section 2.1 for instructions on the proper operation of the diverter valve.
2.4.5 Refer to Hayward document FLVIOM for specific operating and maintenance instructions for the individual vessels installed on this
Duplex Filter. Hayward document FLVIOM is included in the packaging materials of the Hayward FLV Series GFPP Duplex Filter.
2.4.6 Hayward recommends the installation and use, or monitoring, of gauges upstream and downstream the Duplex Filter in order to
monitor the increase in differential pressure that will occur as the bag becomes fouled.
2.4.7 Replace filter bags at 10 psi differential pressure. Filter bags lose efficiency above this level. (See Hayward document FLVIOM)
2.4.8 Applications requiring greater than 10 psi differential pressure must use solid basket. (See Hayward document FLVIOM)
Failure to fully understand and follow the instructions in Section 2.3 of this document and the installation, operation and
maintenance instructions in Hayward document FLVIOM may result in product damage, property damage, personal
2.5 Depressurizing and Draining the Duplex Filter:
The Hayward FLV Series GFPP Duplex Filter should always be depressurized and drained prior to installation, and prior to performing any
maintenance on the full assembled unit.
Failure to depressurize and drain system prior to installing or maintaining Duplex Filter may result in product damage,
2.5.1 To depressurize and drain the Hayward FLV Series GFPP Duplex Filter:
2.5.1.1 Slowly close main shutoff valves installed to the inlet and outlet of the Duplex Filter.
Open and close valves installed to the inlet and outlet of the Hayward FLV Series GFPP Duplex Filter slowly. Rapid increases in
pressure or flow can create excess water hammer effect, resulting in property damage, personal injury, or even death.
2.5.1.2 Slowly open the vent valve installed on the cover of both of the filter vessels on the Duplex Filter unit. The vent valve is opened
by rotating the thumbwheel counter-clockwise.
NOTE: Process media will be allowed to escape through outlet of vent valve as vessel depressurizes. If needed,
install ¼" drain tubing on outlet of vent valve to prevent property damage or personal injury due to contact with
process media. Dispose of vented chemicals properly.
2.5.1.3 After all pressure has been relieved from both vessels, remove plug from drain port in the bottom of each filter vessel and
allow each vessel to drain completely. Capture and dispose of drained chemicals properly. (See Hayward document FLVIOM)
2.5.1.4 For faster draining, the nut of the lower end cap port on each filter vessel can be loosened to allow drainage from this port.
Alternatively, a Hayward TBH Series ball valve can be installed to drain the vessel via this lower port. Caution: Do not lose o-
ring that seals port cap to vessel body.
2.5.1.5 Any liquid contained in the tandem lateral three-way diverter valve manifold should drain into one of the filter vessels as the filter
vessels drain. Check to make sure that all fluids, chemicals, etc., are fully drained from the manifold prior to performing any
maintenance on the Duplex Filter.
Hayward Flow Control
resulting in property damage, personal injury, or even death.
from the "offline" vessel, i.e. the vessel upon which maintenance is being performed.
determine whether there is any pressure in the vessel.
property damage, personal injury, or even death.
www.haywardflowcontrol.com
WARNING
WARNING
injury, or even death.
WARNING
WARNING
1-888-HAY-INDL (1-888-429-4635)
FLV4PDUPIOM Rev A 12/21/2017
Pg. 8 of 10
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