At the point where wastewater enters a treatment plant-the influent gate-a bar screen is typically employed to remove large materials from the wastewater. The bar screen will eventually become clogged and scrapers must clean the bars.
A differential pressure cell, two separate submersible hydrostatic pressure sensors, or ultrasonic sensors may be used to monitor the level of the wastewater on both sides of the bar screen.
When the level differential exceeds a predetermined limit, the bar screen scrapers are activated. The buildup of material is removed to a conveyor. The scrapers continue to operate until the level sensors determine the screen is clear.
Influent flow is metered by means of a flume or weir and the use of ultrasonic sensors equipped with an open channel flow controller from Automation Products Group, Inc.
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Plant Influent Flow Monitor
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| Ultrasonic Level and Flow Sensors |
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High accuracy ±0.10% or 1 mm |
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UV-protected PVC housing; weatherproof |
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Input voltage 120 VAC/240 VAC; optional 24 VDC |
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Microprocessor controller in fiberglass NEMA 4 enclosure |
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Standard RS-232 and 4-20 mA outputs; RS-485 optional |
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Wide sensor operating temperature range: -40 to 160°F
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