Hach 900 MAX - Manual (Page 67)

Section 4
Page 65
8990sensors.fm Submerged Pressure Sensor
3. Place the sensor face up in the bucket or liquid. Tap lightly to remove air
bubbles. If these bubbles are not removed you can receive false readings
from the sensor during calibration (
Figure 17 ).
Note: Always check the Level
Adjust when reinstalling the sampler
following a calibration. (See
Keypad
Description on page 16 .)
4. Place the sensor face down under at least 16 cm (6 in.) of water and wait
20 seconds. Make sure the water surface is calm and the sensor is stable.
5. Press any key to continue.
6. Measure the depth from the bottom of the bucket to the surface of the
water and enter the value using the numeric keypad (
Figure 17 ).
7. Press ACCEPT .
Figure 17 Calibrating the Submerged Area/Velocity Sensor
4.3 Submerged Pressure Sensor
The submerged pressure sensor is a pressure transducer that contains a
titanium diaphragm. As the water pressure increases, (with increasing level in
the flow stream) the diaphragm is deflected, or pushed, against a solid state
device called a strain gauge. The strain gauge converts the pressure against
the diaphragm to a voltage. As the level in the flow stream increases, the
voltage coming from the submerged pressure sensor increases. The voltage
is read by the microprocessor in the Sampler at a regular interval and
converted to a number which represents the level in the flow stream. The level
reading can then be converted by the meter to a flow rate based on the
mathematical formula for the selected primary device.
4.3.1 Submerged Pressure Sensor Connection
The submerged pressure sensor connection is located on the left side of the
controller housing and is labeled submerged pressure sensor. The connector
is keyed and can only be inserted in the proper orientation (key up).