Hach 900 MAX 사용자 설명서

8990sensors.fm

Set the Velocity Units (fps or m/s), using the 

 and 

arrow keys. 

Press 

 to continue.

Highlight Velocity Cutoff, using the 

 and 

keys. Press 

.

Read the Velocity Cutoff information screen. Press any key to continue.

10. Set the Velocity Cutoff using the numeric keypad. Press 

.

11. Set the Velocity Default, using the numeric keypad. Press 

. Press 

 to go back to the Setup Menu or 

 to return to the Main 

Menu display.

This calibration requires a graduated cylinder or bucket with at least 
16 cm (6 in.) of water and a ruler. Calibrating the Submerged Area/Velocity 
Sensor characterizes the sampler electronics to the unique characteristics of 
each individual sensor. In addition, the calibration compensates for any 
sensor drift that may occur over time (6 months or greater) as the materials in 
the sensor age.

The Submerged Area/Velocity Sensor is a pressure transducer that contains a 
stainless steel 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, 
so does the voltage coming from the Submerged Area/Velocity Sensor. The 
voltage is read by the microprocessor in the sampler at regular intervals and 
converted to a number that represents the level in the flow stream. 

The manufacturer recommends calibrating the submerged area/velocity 
sensor when:

The sensor is first used.

Installing a new or different sensor on a flow meter or input receptacle.

The difference between the level reading of the flow meter and the 
independent verification (measurement with a dipstick or ruler) 
is increasing.

From the Main Menu, select 

Place the sensor flat on a table top or floor with the sensor (the plate with 
holes) facing down onto the surface (

). Press any key to 

continue.