Does Lachat have a procedure for back flushing internal sample loop (ISL) valves?

Document ID

Document ID TE3426

Version

Version 5.0

Status

Status Published

Published Date

Published Date 01/29/2019
Question
Does Lachat have a procedure for back flushing internal sample loop (ISL) valves?
Summary
ISL back flushing procedure
Answer
This can be applied to the QC8500 ISL valve assembly (Product # 85281).

Wear goggles, as a clog may "pop" audibly and forcibly.

 
  1. Verify pump tubes for the autosampler are clamped down and the pump is running. This is typically a green pump tube (goes to sampler probe) and a purple pump tube (goes to wash bath). If both lines are pumping, the water from the sample line can be used to flush. This assumes the autosampler probe is down in the wash bath or other water source so that it will be pulling water. Use the sample line for back flushing. It may help to put some paper towels next to the open port to absorb the water that should flow freely. 
     
  2. Disconnect the sample line from port 6 and the plug it into port 5. Water should come out of port six.  The max speed option on the pump can be used to give it extra pressure. 
     
  3. Manually toggle the valve to the load state. Go to the timing tab within the run properties window. One or more boxes will be visible in the upper right-hand corner. These allow one to toggle the valve back and forth. Click within the numbered box which matches the channel the valve is on. For example: If working with the valve on channel 1 click on the box labeled 1. If working with the valve on channel 2, click on the box labeled 2, etc. When the box shows a green pathway, the valve is in the inject position and the water will come out of port six. When the box shows a red pathway, the valve is in the load position and the water will come out of port four.
  4. Repeat this for port 3 and port 2 if needed. 
  • Remove the carrier line going into port 3.
  • Hook up the line from port six to port 3 and do the same flushing. 
  • When finished, hook the lines back up to normal again,
  1. Back flushing can be done with the carrier line instead of the sample line. In this case a solution can be used to dissolve the clog, such as 1 M HCl (hydrochloric acid).
  2. Use of a syringe (Product # 28120) with a female luer to 10-32 male thread, adapter (Product # 28016) can be considered if the plug does not dislodge.
    • Remove the valve fitting from port 6.
    • Pull through port 6 while the pump is pushing through port 5.
  3. Use of two syringes may also be considered to try to dislodge the clog.
    • Turn off the pump. (The valve should still be in the INJECT state).
    • Using the two syringes, push air into port 5 while pulling through port 6. You will need to remove the valve fitting from both port 5 and port 6, pushing through port 6 and pulling through port 5 may also be tried. This may require two people to accomplish.
 Replace or service the valve if none of these steps resolve the issue.




Valve Diagram:
  • LOAD: Sample stream goes in port 6, through the internal loop and out port 5 to waste.

Carrier stream goes in port 2 and out port 3 onto manifold

  • INJECT: Sample Stream goes in port 6 and out port 5 to waste.

Carrier Stream goes in port 2, through the internal sample loop, and out port 3 onto the manifold.

Attachments
Internal Notes

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