Hach QC8500 Series 2 - Inject State

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Operation
The injection valve has two states: the inject state and the load state. The valve will be
moving bi-directionally between those two states. When the system is not in operation,
the valves rest in the inject state.
4.1.1 Inject state
When the valve is in the inject state, the carrier stream is pumped into port 2 and directed
to port 1 to flow through the sample loop. The carrier then comes out port 3 and flows on
the manifold.
The sample stream goes into port 6 and out of port 5 to waste. Refer to Figure 26.
During the inject state, the sample loop is filled with carrier. When the valve switches to
the load state, some carrier will be trapped in the sample loop. The carrier that was
trapped in the sample loop at the inject state will be swept out to waste by the sample
stream. The sample stream will pass through the sample loop and eventually go to waste.
Figure 26 Inject state
1 Sample loop 4 Waste line/next valve
2 Carrier line 5 Sample line/tubing from adjacent valve
3 To manifold
1
6
5
2
3
4
1
2
3
4
5