discharge valve to open, and the oil discharge
The three pressure vessels (stages) each have
a removable cover that provides access to the filter
valve to close.
elements. Mounted on each cover is an air
eliminator valve to discharge any air displaced by
The processed water effluent from the first
the effluent. Each vessel has a sight glass through
stage is discharged into the second-stage prefilter.
which water clarity and oil level can be monitored
The second stage, which has a single prefilter
and a manually operated drain valve for draining
element, performs the dual function of removing
the stage. The first-stage vessel has a pressure
particulate matter and oil that were not separated
in the first stage. The replaceable prefilter element
gauge connected to monitor its fluid outlet
pressure. Connected into the second and third
is designed for inside-to-outside fluid flow. As
stages are differential pressure gauges that indicate
fluid flows from the inside to the outside of the
the difference between the inlet fluid pressure and
filter element, oil droplets form on the surface of
the outlet fluid pressure of each stage. The first
the element. As the oil droplets form to sufficient
two stages have a capacitance-type level detector
size, they are forced off the surface by fluid flow.
probe that senses an accumulation of oil and
This attach-detach process works solely through
electronically signals the opening of the solenoid-
fluid flow and requires no moving parts. The
operated oil discharge valve.
detached oil droplets rise and accumulate at the
top of the vessel. If an element becomes clogged
The fluid enters the first stage (the gravity
or its surface chemically contaminated, it is
plate separator), where the primary separation and
easily replaced. When enough oil collects in this
removal of the oil from water is accomplished.
stage to reach the level of the level detector
Particulate matter, too small to be separated by
probe, oil is automatically discharged in the same
the duplex strainer, is removed for the fluid in
manner as in the first stage.
the first stage. The first stage is designed to
significantly reduce the fluid velocity of the
The processed water next enters the third-stage
incoming oily mixture. The resulting decrease in
separator, which is identical to the second stage
velocity permits oily-water separation to occur
in its function and operation, except that it is
naturally from the effect of gravity. Oil drops in
equipped with a manually operated oil discharge
valve instead of a solenoid-controlled oil discharge
the fluid are separated from the water due to the
reduction in fluid velocity that occurs as the fluid
valve. Very little oil will accumulate in the third
exits the inlet line and enters the vessel interior.
stage since most, if not all, of the oil will be
The oil drops rise and accumulate at the top of
removed in the first two stages. The third stage
the vessel. Oil drops that do not rise to the top
serves primarily as a backup to the second stage.
of the vessel are removed through coalescence by
The clean water effluent leaves the third stage and
the inclined adsorption plates on the bottom of
enters the water discharge line.
the vessel. The plates provide a collection surface
upon which any residual oil not gravitationally
The electrical circuit for the control power that
separated will collect (coalesce) and separate from
operates the oil level sensors and the solenoid-
the flow. Holes drilled in the plates permit the oil
operated valves is such that only one of the
electrically operated valves can be activated at a
droplets to rise to the top of the vessel. Solids are
removed from the fluid in this stage. The air
given time. If simultaneous oil discharge signals
displaced by the rising fluid level in the pressure
from both oil level sensors occur, the logic allows
vessel is discharged through the automatic air
only one stage to discharge oil at any given
eliminator valve mounted on the cover of the
time. The system operation is fail-to-safe in
vessel.
that all electrically operated valves close with-
out power. The oily-water separator must be
The oil is automatically discharged from the
manually started, but will be automatically shut
first stage when the level detector probe senses the
down when the liquid level sensor switch in the
oil and electronically signals the simultaneous
oily waste water holding tank drops to a preset
level.
opening of the solenoid-operated oil discharge
valve and closing of the solenoid-operated clean
water discharge valve. The valves remain in
Detailed procedures for operating and main-
taining the oily-water separator are furnished by
the position until enough oil is discharged to
the EOSS, MRCs, and the manufacturers'
uncover the probe. This causes each valve to
technical manuals. Carefully follow these written
return to its original position, the clean water
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