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Comments
When
in the INJECT position, the siphoning may continue until the vent tube
and needle port are empty. When in the LOAD position, the siphoning may
continue until the vent tube, needle port, and loop are empty.
If you use a long vent tube to go below the fluid level in a low waste reservoir, there will be a large siphoning force and special precautions may be needed. One reason to make such a connection is to prevent evaporation from the end of the tube, which can result in buffer salt crystallization and blockage. If you are loading excess sample to completely fill the loop, air sucked into it prior to inserting the syringe may be displaced. But if you are partially filling the loop, air may not be displaced completely. In this case, you can prevent air from entering the loop by inserting the syringe containing the next sample while still in the INJECT position just before returning to LOAD. This will prevent siphoning from the loop.
When the loop empties due to siphoning, it fills with air, the presence of which can cause the system pressure to decrease when the handle is turned to INJECT. See Symptom #10.
Symptom #2
Fluid leaks out the needle port or vent tube(s), but eventually stops (see Fig. 6):Slowly insert the syringe needle all the way into the needle port and notice the friction:
- If the
fluid leaks out the vent tube(s), see Cause A.
- If the fluid leaks out the needle port, see Cause B.
Fig.6. Leaks out vent tube and needle port.
Cause A
The vent tube(s) is lower than the needle port, which causes fluid to siphon out (see Fig. 7).Solution
Adjust the vent tube(s) so that its outlet is at the same horizontal level as the needle port.
Fig. 7. Vent tube low relative to needle port can cause siphoning out the vent tube.
Cause B
The vent tube(s) is higher than the needle port, which causes fluid to siphon out (see Fig. 8).Solution
Adjust the vent tube(s) so that its outlet is at the same horizontal level as the needle port.
Fig. 8. Vent tube high relative to needle port can cause siphoning out needle port.
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