0003 00
TM 55-1925-285-13&P
SAMPLE AND DETECTION SUBASSEMBLY (SDA)
The SDA (figure 3, item 5; figure 5) controls the flow, emulsification, and turbidity measurements of the effluent
sample. It consists of a plastic manifold block with the following components mounted to it: a pressure switch
(figure 5, item 1), two solenoid valves (figure 5, items 2 and 3), an ultrasonic vibrator (figure 5, item 4), and a
turbidimeter (figure 5, item 5), which takes the turbidity measurements using photoelectric components.
4
6
5
3
2
1
DRAIN INLET
Figure 5. Sample and Detection Subassembly (SDA)
ELECTRONIC COMPONENTS AND CONTROLS
The sampling/sensor assembly provides the following controls and components:
OPERATION SELECTOR switch A1S1 (figure 6, item 1). This switch is a three-position toggle switch (AUTO,
OFF, and TEST positions) used to select the mode of operation. With switch A1S1 in the OFF position, none of
the system indicators or displays will energize, and the diverter solenoid valve will remain in the recirculate (de-
energized) position. With the switch in the AUTO position, the OCM will be energized whenever there is 5 to 25
PSI (0.3 to 1.7 bar) at the sample inlet, as detected by a pressure switch (figure 3, item 6) that is part of the SDA.
Pressure at the sample inlet is normally created by the OWS discharge pump, however flushing water pressure
will operate the OCM when the sample inlet valve is closed and the flushing inlet valve is opened. The OCM
indicators will energize when the required pressure is applied in this AUTO mode. With switch A1S1 in the MAN
position, the OCM is energized regardless of the sample pressure or flow. The MAN position is only to be used
for troubleshooting and system verification, as operation of the OCM without adequate pressure or flow can
damage the unit.
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