How is valve timing optimized on the Lachat QC8500 FIA when running more than one channel at a time?

Document ID

Document ID TE5439

Version

Version 6.0

Status

Status Published

Published Date

Published Date 03/07/2019
Question
How is valve timing optimized on the Lachat QC8500 FIA when running more than one channel at a time?
Summary

Multi-channel valve timing

Answer
Running multiple channels together requires some additional considerations when optimizing valve timing. This is primarily because the turning of the valve on the first channel will have an effect on the timing to the valve of subsequent channels. 

To set valve timing when working with multiple channels:
 
  1. Set time to valve for one channel at a time. Start with the first valve being used. So if channel 1 is included it would be timed first. Use the How is valve timing optimized on the Lachat QC8500 FIA   to perform this.
  2. Set the time to valve for the next valve being used. Time to valve may not be exact so  be aware that a small amount of dye may get past the first valve. This must be ignored when timing later valves. The main slug of dye which will pass through the sample loop of the previous channel(s) before reaching port 6 of the next valve is what must be timed.
  3. Repeat set 2 as needed for each additional channel being used.
  4. Verify the sample period. Each method will have its own sample period. Once time to valve is set for all of the channels in the method, verify that each loop is still full of dye for each valve when the valves turn to inject. If it is noticed that the dye runs out before the last valve turns to inject sample, the sample period will need to be increased. Starting with a large sample period may result in plenty of dye before the valves after the last valve turns to inject. In this case the sample period can be decreased.

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