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Sensor setup
5. Select the Liquid Depth method and enter the new level.
6. Take a physical measurement of the liquid depth (level) and enter the value.
7. Press
ACCEPT when finished.
6.2.2.2 Sensor height
This method requires you to enter the distance between the face of the ultrasonic sensor
and the zero flow point in the primary device. The zero flow point in a primary device is
the level at which flow ceases. In a round pipe the zero flow point would typically be the
invert or bottom of the pipe. In a V-notch weir the zero flow point occurs when the liquid
behind the weir is level with the bottom of the ‘V’. (There would still be liquid behind the
weir plate but it would not be contributing to flow). Sensor Height calibration is generally
used when:
• Access to the primary device is difficult (confined space entry) or
• There is no liquid flowing during installation of the flow meter.
1. From the Main Menu, select
OPTIONS, ADVANCED OPTIONS, CALIBRATION,
ULTRASONIC SENSOR.
2. Select Calibrate U-Sonic using the UP and DOWN keys. Press SELECT.
3. Select Standard as the type of Ultrasonic Transducer using the
CHANGE CHOICE key.
Press
ACCEPT to continue.
4. The speed of sound in air varies with the temperature of the air. The ultrasonic
sensor is equipped with temperature compensation to help eliminate the effect of
temperature variation under normal site conditions.
5. Enter the ambient air temperature at the transducer location. For optimum results,
allow enough time (100 minutes) to ensure that the sensor is at equilibrium with the
surrounding ambient temperature. Press
ACCEPT.
6. Select the Sensor Height method and enter the new level.
7. Enter the distance from the face of the transducer to the zero flow point of the
primary device.
8. Press
ACCEPT when finished.
6.2.2.3 Setting the invisible range
1. From the Main Menu, select OPTIONS, ADVANCED OPTIONS, CALIBRATION,
ULTRASONIC SENSOR.
2. Select the Invisible Range option using the UP and DOWN keys. Press SELECT to
continue.
3. Enter the Distance to End of the Invisible Range.
4. Select either inches or centimeters using the
CHANGE UNITS key. The distance must
be greater than the minimum deadband of 9 in. (22.9 cm) for the 40kHz sensor.
5. Press
ACCEPT when finished.
6.3 Submerged area/velocity sensor
Submerged Area/Velocity Sensor utilizes a pressure transducer in conjunction with the
Doppler method of velocity measurement to calculate flow in open channels. A small
sensor containing both a transducer and velocity sensor is affixed in the flow stream. The
instrument reads the pressure of the water and converts it to a level reading. The
instrument then calculates the ‘wetted area’ of the flow stream utilizing the user centered
channel shape. Once the wetted area and the velocity are known the following formula is
Goodnal STP ST041 Pre Treatment (Sigma 900 MAX All Weather Refrigerated Sampler) Vendor Manual
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