Hach 8000A Manuel D'utilisation page 18

The counter can be configured to do a quick adjust cycle automatically at
periodic intervals. Refer to the Quick Adjust rate parameter in GLOBAL
SETUP.
A counter may occasionally fail a Quick Adjust even when the counter is
in good working condition. The typical reason for a counter to fail a Quick
Adjust is a change in operating conditions since an Auto Adjust was
done. Do another Quick Adjust.
If no errors occur, the counter can be used. If an error persists, do an
Auto Adjust before continuing.
Dual sensor calibration
A dual range sensor gives two outputs. The possible outputs are:
• A scattering signal for small particles and an extinction signal for large
particles
• A high gain signal for small particles and a low gain signal for large
particles
Thus, two calibrations are supplied with this sensor. One curve is for the
scattering or high gain signal, i.e., the small curve. The other curve is for
the extinction or low gain output, i.e., the large curve.
1. In the Main Functions menu, push CAL.
The Calibration functions menu appears.
2. Push SET CAL.
The display shows the Set calibration functions menu.
3. Push ALTER CAL.
The display shows the ALTERCAL screen.
4. Enter the sensor model, sensor serial number and the sensor type.
5. Push the up or down arrow key to select Dual Mode, then push
Enter.
The display shows the Calibration #1 screen. There must be some
overlap between the small and large calibration curves.
6. Enter values for the screen parameters.
Option Description
Sensor noise The value in mV that represents sensor noise
18 English
Option Description
Scatter data The number of calibration data points in the small
points calibration curve. Enter at least 6 data points. Enter the
particle size in micrometers or in micrometers certified and
the corresponding sensor output in millivolts. Enter the
data in ascending order according to particle size.
Extinction data The number of calibration data points in the large
points calibration curve. Enter at least 4 data points. Enter the
particle size (µM) and the corresponding sensor outputs
(mV) in ascending order by particle size.
7. Select BIN SIZE from the control panel and enter the bin sizes (µM).
Set the bin sizes as required by the application and the specifications
of the sensor (min/max particle resolution).
The counter assigns each channel to one of the sensor outputs. This
screen is accessible by pushing BIN MV. The determination is based
on the overlap between the small and large calibration curves. The
midpoint of the overlap between the small and large curves is found
by averaging the largest particle size in the small curve and the
smallest particle size in the large curve. Any channel set to a particle
size greater than the mid-point of the overlap is assigned to the low
gain or extinction channel.
8. Push PRNT CAL to get a hardcopy of the calibration parameters.
Additional calibration functions menu
1. In the Main Functions menu, push CAL.
The Calibration Functions menu appears.
2. Push More.
The Additional Calibration Functions menu appears.
3. Push the key for a function. (Push EXIT to return to the Main
Function menu.)
Option Description
Auto Adjus Does an automatic adjustment of counter circuits.
Quick Adjus Does a quick adjustment of channel threshold voltages