Feed Water Booster Pump (1). This centrifugal pump receives water from the raw water discharge hose and pressurizes
it so it can go through the filtration steps which follow.
Basket Strainer (2). The WTA-060 Model is equipped with only one basket strainer. The ROWPU-1 Model is equipped
with two basket strainers to allow the replacement of a clogged strainer without shutting down the ROWPU. The basket
strainer removes any remaining large foreign particles not removed by the cyclone separator(s). This prevents clogging of
the water distributors inside the media filter. A spare strainer basket is carried on-board to provide for quick change when
the basket strainer becomes dirty. When the basket strainer gets dirty, the pressure at the basket strainer outlet becomes
lower than the basket strainer inlet. The ROWPU controls sense that pressure drop (or differential) and set off a yellow
strainer plugged warning light and pulsing horn.
Media Filter (3). The media filter removes most of the suspended solids. The water enters the top of the filter through the
upper distribution flows downward through one layer of course AG filter media and a final layer of very fine garnet sand.
These layers are all supported by three layers of support gravel. A collector picks up the filtered water for discharge. The
suspended solids are too small to be removed by the straining action of the filter media and many of the particles contain
layers of electrical charges which prevent them from forming larger particles. The secret to removing these particles is the
addition to the feed water of a treatment chemical called polyelectrolyte. With the aid of this chemical, the filter can
remove most of the suspended solids from the water resulting in a turbidity between 0.5 and 2 NTU in most cases. On
Model WTA-060, the turbidity is measured by a continuous reading Turbidity Meter (5). On Model ROWPU-1, turbidity is
measured by taking readings using the portable turbidity meter.
Cartridge Filter (4). This filter contains ten 30 in. (76 cm) filter cartridges. Water goes through these filters for final
(polishing) filtration. When it has gone through this filter, the water will normally have a turbidity of 0.5 to 1.5 NTU. In
time, these cartridges will become dirty. When the cartridge filter gets dirty, the pressure at the cartridge filter outlet
becomes lower than the pressure at the cartridge filter inlet. The ROWPU controls sense that pressure drop (or
differential) and set off a yellow cartridge filter plugged warning light and pulsing horn. The ROWPU must be shut down
and the dirty cartridges replaced.
Figure 1-10. Normal Flow Thru Filters (Sheet 1 of 2)
(MODEL WTA-060 ONLY)
Change 12 1-14.1/(1-14.2 Blank)