ADS Environmental Services Model 3600 530002 A2 - Manual (Page 125)

Features and Specifications A-7
Depth Subsystem
The depth subsystem includes the ultrasonic depth sensor and the pressure depth
sensor. This subsystem also includes the depth board.
Ultrasonic Depth Sensor
The following table contains information and specifications for the ultrasonic depth
sensor.
Measurement
Technique
Ultrasonic pulse echo ranging measures the elapsed time between the transmission of
the ultrasonic signal to the flow surface and echo reception. Each reading by a sensor
includes up to 32 individual transmissions/receptions for each active ultrasonic
transducer pair. All false or multiple echoes are discarded; remaining readings are
averaged into an elapsed time. This time is then compensated for air temperature
changes. Using the speed of sound, the range, i.e., the distance between the sensor
and the flow surface, is calculated based on this compensated average elapsed time .
The depth of flow equals the range minus the pipe diameter.
Accuracy The depth sensor has an accuracy that is within 3 mm (0.125 in.) or 0.5% of reading,
whichever is greater.
Frequency 40 kHz
Quadredundancy Up to four ultrasonic depth transducers can be used to determine depth of flow, ensuring
more reliable data. These four active transducer pairs are selected from twelve
combinations.
Individual transducers can be enabled or disabled remotely at the central computer in
case of a malfunction.
Calibration Long-term calibration of depth of flow can be verified by comparing readings from each
ultrasonic depth transducer with each transducer’s performance, other transducers’ past
performances, and with field calibrations.
Temperature
Compensation
Two temperature sensors located within each sensor compensate for temperature
variations and minimize any measurement distortions due to changes in the speed of
sound in air.
Housing
The housing dimensions are 19.05 cm (7.5 in.)
×
10.79 cm (4.25 in.)
×
22 mm (0.875
in.). It is made of saltwater marine aluminum (6061T6) or stainless steel.
Effective Range The sensor has a range up to 2.4 m (8 ft) and a dead zone of 13 mm (0.5 in.); greater
ranges are available.
Installation The sensor is mounted at the top of a sewer pipe on an expandable stainless steel ring,
or it can be bolted directly to the crown (soffit) of the pipe.