Tips On Using Injectors

Exploded View of Injectors

Leaks
#1. At needle port — only while loading
#2. At needle port or vents — but stops
#3. At port, vents, or stator — continuously

Artifact Peaks
#4. Carryover (miniature chromatogram)
#5. Spurious (unknown) peaks
#6. Distorted - fronting, tailing, broad

Non-Reproducible Results
#7. All peaks have poor area precision
#8. Some peaks have poor area precision
#9. All peaks are small or absent

Decreased System Pressure
#10. Falls when inject, then returns
#11. Falls when switch, then stays low

Blockage – High Back Pressure
#12. Cannot load loop
#13. High system pressure

Noise or Drift
#14. Baseline is noisy or drifting

Appendices
A. Drawings with part numbers
B. Adjusting pressure setting
C. Non-injector sources of artifact peaks
D. Oxygen peak artifacts
E. Flushing between injectors
F. What happens inside the injector  

How to Use This Guide
This Troubleshooting Guide discusses Rheodyne Models 7125, 7126, 7725, 8125, 8126, 9725, and 9726. Exploded View of Injectors shows the internal parts of a generic injector. Appendix A shows specific models.

Inside Injectors
High pressure switching and sealing takes place between a ceramic stator face assembly and a polymeric rotor seal. The rotor seal wears with use and usually is the only part that may need replacement. In normal use it will last many thousands of injections. Rheodyne RheBuild™ Kits are available for all injectors. Kits contain only genuine Rheodyne parts together with tools and instructions.

When you have a problem, do not assume that replacing the rotor seal will always be necessary. Find your problem in the table of contents to the left and proceed as instructed.

The "comments" section on each page has useful supplemental information.

Fittings, Sample Loops, and Tubing
Rheodyne established color-code standards for valve fittings as a convenient means to visually identify and trace tubing connections. The illustration below shows brightly colored ChromTRAC™ knobs. Ordering information is located at www.rheodyne.com. To order, contact an authorized Rheodyne Distributor.