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Stainless
steel and PEEK sample loops are factory-cut and finished to the
highest quality. The 316 stainless steel loop ends have a square
cut and are burr-free for a flush connection to the valve.
The flexible PEEK loop ends are provided with a clean and straight
cut for easy installation onto the valve.
Stainless steel (and titanium) sample loops are supplied with
unswaged fittings. The two ends of the loop must be completely
bottomed in the injector ports before the ferrule is swaged onto
the loop. Swaging each end separately and then replacing the ends
in their respective ports of the same valve ensure that the loop
ends are bottomed into the ports. A fitting made up in one port
may leave an undesirable cavity in another port. As all ports
vary in all valves, careful attention to loop installation is
important.
PEEK loops are also supplied with unswaged RheFlex ® fittings
but do not require the same swaging precaution. The fittings can
reposition along the loop tubing when the fitting reinserts in
the ports for correct loop installation.
Stainless Steel Stainless
steel and titanium sample loops are available. The size designations
of loops are nominal. The actual volumes can differ from the theoretical
designations because of the ± 0.025 mm (0.001") tolerance of the
metal tubing bore. Accuracy of large metal loops (1.0 mm, 0.040"
bore) is about ±5%, intermediate loops (0.5 mm, 0.020" bore) ±10%,
and small loops (0.2 mm, 0.007" bore) ±30%. Since both standards
and unknowns are usually analyzed using the same sample loop,
knowledge of the actual, accurate volume is rarely needed. If
the sample loop volume must be known, it is best to calibrate
the loop in place on the valve so the flow passages in the valve
are also taken into account. An alternative to calibration is
to use a dual mode injector and partial-filling method of loading.
See Tech Tip #6 on page 21.
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