A. GENERAL
Level-Velocity Logger to consist of a submersible ultrasonic sensor, connecting cable, and a remote enclosure with electronics and display. System shall have no moving parts.
Level measurement accuracy shall be ±0.25% of Level. Velocity measurement accuracy shall be ±2% of reading
B. SENSING ELEMENT
Ultrasonic sensor shall be rated IP68 for continuous submersion in liquids.
Using the ultrasonic Doppler principle, the sensor shall measure fluid velocities from 0.1 to 12.5 ft/sec (0.03 to 3.8 m/sec).
Using ultrasonic echo-ranging principle, the submerged sensor shall measure liquid level from 1" to 15 ft. (25.4 mm to 4.57 m) above the bottom of the pipe or channel. Minimum detectable level shall not be greater than 1" (25.4 mm). Level sensing circuitry shall include a temperature sensor for automatic temperature compensation.
Sensor shall be constructed of 316 stainless steel and epoxy resin.
Sensor operating temperature shall be from 5°F to 175°F (-15°C to 80°C).
C. SENSOR CONNECTING CABLE
Provide minimum length 25 ft (7.6 m) tri-coaxial cable with potted bond to the Sensor head. Sensor cable shall be waterproof and electrically shielded. Exposed material shall be polyurethane only.
Sensor shall include a watertight plug for connection to the instrument electronics.
D. LOGGER ELECTRONICS
No calibration shall be required. The Level-Velocity Logger shall measure liquid level from the bottom of the pipe or channel, and flow velocity.
Logger electronics operating temperature shall be from –5° to 140°F (–20° to 60°C).
Shall have USB output to transfer log files to a Windows™ computer or laptop.
Provide an LCD bar graph display to indicate level, velocity and temperature readings, plus remaining battery and logger storage capacity.
Shall be housed in a watertight IP67 enclosure with hinged, latching cover and watertight sensor cable entry.
Logger capacity shall be 130,000 data points. Each data point includes level, velocity and temperature reading.
Logger sample rate shall be user-selectable from 10 or 30 seconds, 1, 2, 5, 10, 30 or 60 minutes.
Shall be powered by 4 D-cell Alkaline batteries. Battery life shall be matched to Logger storage capacity: 15 days at 10 second sample rate up to 4 years at 60 minute sample rate.