Hach-Lange SIGMA SD900 Refrigerated Sampler and All Weather Refrigerated Sampler User Manual - Manual (Page 41)

39
Installation
3. Make sure the pacing or time interval in the sampler program
allows enough time for the pump to be off between sample
cycles.
Note: When the ambient temperature is 50 °C (122 °F), do not allow the
pump to run continuously for more than 10 minutes.
Examples
1. Assume that the pump is on continuously for 10 minutes for a
given sample cycle. On the graph, find 10 minutes on the
bottom (horizontal) axis. Draw a vertical line up from the 10
minute mark until it intersects the 50 °C (122 °F) line. From the
intersection, draw a horizontal line to the left to the vertical axis.
The point where the horizontal line intersects the vertical axis,
in this case 30 minutes, is the time in minutes that the pump
must stay off before the next sample cycle begins.
2. Assume that the pump is on continuously for 2 minutes. The
pump must stay off for at least 6 minutes before the next
sample cycle begins.
Electrical transients
It is good practice to use a power line filter or connect the controller
to a different branch circuit to reduce the chance of transients.
Figure 21 Sampler pump—time on vs. time off at 50 °C (122 °F)
1 Time (in minutes) when the pump must stay off 3 Time (in minutes) when the pump is on continuously
2 Example—if the pump is on for 5 minutes, the pump must stay off for 15 minutes before the next sample cycle