Hach ABS-2 Manuel D'utilisation page 13

Table 1 Control descriptions
Control Description
Flow control valve Adjusts the rate at which the sample flows
through the sensor.
Sitr bar speed controller Adjusts the rotation speed of the stir bar.
Vacuum/Pressure mode Puts the instrument in Vacuum or Pressure
switch operation mode.
Manual/Auto mode switch Puts the instrument in Manual or Automatic
operation mode.
Pump control switch Turns the optional remote pressure/vacuum
pump on or off.
Vacuum control valve Adjusts the vacuum in the sample chamber. The
pressure/vacuum gauge shows the amount of
chamber vacuum.
Pressure control valve Adjusts the line pressure in the sample
chamber.
Pressure/vacuum gauge The pressure/vacuum gauge shows the amount
of chamber pressure.
Electromagnetic stir assembly
Particles in the sample liquid must stay suspended as a sampling
operation occurs. A magnetic field makes the stir bar rotate in the
sample. This action stirs the sample at a constant speed and keeps the
particles suspended. The user adjusts a control on the front of the
instrument to change the stir speed.
Make sure that the stir bars are:
• Clean (particle free)
• Sensitive to magnetic fields
• Covered in glass or another material that does not give off particles
• Non-magnetic
Adjust the flow rate
Note: Do not over-tighten the flow control valve as this can permanently damage
the micro-valve assembly.
The initial settings for a sample operation are:
• Flow valve fully open
• Line pressure 20 psi (137.8 kPa)
Adjust the flow control valve and the line pressure so a specified volume
fills the sight tube in a specified amount of time.
For best results, adjust the flow rate of the sample fluid to be the same
as the calibrated specification for the sensor.
1. Set the volume level detector at the calibrated flow rate volume for
the sensor.
2. Set the pressure/vacuum switch to Pressure.
3. Make sure that a clean (particle free) stir bar is in the sample bottle.
Then put the sample bottle on the stir assembly and lock the stir
assembly to the sample chamber.
4. Turn on the automatic bottle sampler.
5. Set the auto/manual switch to Automatic and configure the particle
counter for volume mode operation.
6. On the counter, push START.
Sample fluid flows and becomes visible in the sight tube.
7. Start the timer when the sample is at the 0 in the sight tube.
8. Stop the timer when the counter stops the bottle sampler.
The remote pump (if used) turns off and the sample chamber fumes
are removed.
9. Adjust the flow rate of the bottle sampler as necessary.
a. If the time necessary to get the expected sample volume is
greater than 1 minute, turn the flow control valve clockwise or
decrease the line pressure.
b. If the time necessary to get the expected sample volume is less
than 1 minute, turn the flow control valve counterclockwise or
increase the line pressure.
English 13