Hach 900 User Manual

 

8544operations.fm

To exit the manual mode, press 

. This returns the sampler 

to the standby state.

While the sampler is in standby, a sample cycle can be initiated by pressing 
the 

 key.

The sampler can operate in any one of three control modes, using an external 
controlling device (i.e. Liquid Level Actuator, Cat. No. 943, or an external flow 
meter). In any of the three modes, the sampler remains in a standby state until 
liquid at the sample source reaches a predetermined level. This feature may 
be also used to access the setup of the storm water monitoring program, First 
Flush. The three modes are described below:

Mode 1
The instrument collects a sample within the first minute that the liquid rises to 
the predetermined level. After the first sample is taken, the sample interval 
automatically resets to the programmed interval. 

If the liquid falls below the predetermined level, the sampler continues 
to collect samples at the programmed time or flow interval, until the 
program ends.

Mode 2
The instrument collects a sample within the first minute that liquid rises to the 
predetermined level. After the first sample is taken, the sample interval 
automatically resets to the programmed interval. The sample program ends if 
liquid falls below the predetermined level. If the liquid again rises to the 
predetermined level, a sample is taken within the first minute and the interval 
automatically resets to the programmed time or flow interval.

Mode 3
When the liquid rises to a predetermined level, a sample is not taken 
immediately. A sample is taken only when liquid is at or above the 
predetermined level and after the programmed sample interval has elapsed. 
The interval between samples counts down and resets even when the liquid 
level is below the predetermined (actuation) level. This mode is used to 
synchronize sample collection with a real-time clock when sampling in the 
time mode.