SCOPE: This specification covers a portable
Level-Velocity Logger as manufactured by Greyline Instruments, Massena, New York
/ Long Sault, Ontario. The instrument shall provide for measurement and data
logging of level, velocity and temperature readings from flow in open channels
and partially filled or surcharged pipes.
- 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
m/sec). The fluid shall contain bubbles or solids with a minimum size of 100
microns and a minimum concentration of 75 ppm to act as acoustic reflectors.
- 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 PVC,
stainless steel, polyurethane and epoxy.
- Sensor operating temperature shall be from
5°F to 150°F (-15°C to 65°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
- 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
- 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.
E. PC SOFTWARE
- Shall include Windows™ software to retrieve,
display, save and export log files from the Level-Velocity Logger. Shall
support Windows versions including XP, Vista, 7 and 8.
- Shall convert level-velocity readings to
flow for channel shapes including round pipes, rectangular, trapezoid and
egg-shaped channels. Shall convert level readings to flow for flumes and
- Shall provide 'real-time' communication with
the level-velocity logger to display readings with a refresh rate of 10
seconds or less.
- Shall permit the operator to set logging
rate of the level-velocity instrument from 10 or 30 seconds, 1, 2, 5, 10, 15, 30 or
- Shall display battery life remaining and
logger capacity remaining.
- Shall display, save, output to a printer and
export level-velocity log files in graph and tabular format. Export log files
shall be delimited for import to spreadsheet or database programs.
- Shall permit conversion of linear and volume
F. OPTIONAL FEATURES FOR INSERTION AS REQUIRED
- Shall include 50 ft / 15 m length sensor
cable extension with watertight connector plugs to permit sensor installation
total distance of 75 ft / 23 m from the electronics enclosure. Cable extension
shall be shielded, submersible with a durable polyurethane coating.
Level-Velocity Logger shall be
model by Greyline Instruments and warranted against defects in materials and
workmanship for one year.
Software shall be 'Greyline Logger' by