Hach-Lange SD900 Refrigerated Sampler, SD900 AWRS User Manual - Manual (Page 18)

W A R N I N G
Electric shock hazard. The power supply can overheat when the time between pump cycles is too
short.
The power cord is installed at the factory. Plug the power cord into an electrical outlet. The
instrument starts automatically. The refrigerated sampler has a power cord for the controller and a
power cord for the sampler unit. Plug both cords into the electrical outlet.
Use a power line filter or connect the controller to a different branch circuit to reduce the possibility of
electrical transients.
Calculate the pump cycle time
The pump must stay off for a minimum time period between sample cycles so that the power supply
does not overheat.
1. Calculate the total amount of time that the pump will run continuously during a sample cycle.
Include all stages: pre-purge, intake rinse, sample, sample retries and post-purge.
2. Find the minimum amount of time that the pump must stay off between sample cycles from
Figure 11 .
3. Make sure that the pacing or time interval in the sampler program lets the pump stay off between
sample cycles for the minimum amount of time.
Figure 11 Pump on and off times at 50 °C (122 ºF)
1 Time (in minutes) that the pump must stay off 3 Example: if the pump is on continuously for
5 minutes, the pump must stay off for 15 minutes.
2 Time (in minutes) that the pump is on continuously
Startup
Turn the instrument on or off
The refrigerator starts after a 5-minute delay when the equipment is plugged in. Push the POWER
key to turn on or turn off the controller. The refrigerator continues to run when the controller power is
turned off. Unplug the power cord on the AWRS or both power cords on the refrigerated sampler to
turn off the entire instrument.
User interface and navigation
The controller keypad is shown in Figure 12 . Use the MENU key to set up sampling programs,
configure the controller settings or complete the diagnostic tests. Use the arrows, ENTER and BACK
keys to scroll through the menu, make selections and enter values. Look for arrows on the bottom or
side of the display screen to know when more options are available.
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