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VALVES
APPLICATIONNOTE
UsingProper SyringeNeedles
With front-loading injection valves it is important touse thecorrect
needlewhen loading the sample loop.An incorrect needlewill damage
the valveandcancausepoor reproducibility.When theneedle is too
short the tipwill not reach theneedle seal.When theneedle is too
small indiameter the sealwill notgrip tightlyenough.Needleswitha
beveled tipcandamage the rotor seal and stator faceassembly (see
Figure1). Theneedle shouldbe#22gauge (0.028”–0.0285”/ 0.72mm),
and90°point style (squarecut end).Model 3725 requiresa#16gauge
(0.0645”–0.0655”/ 1.65mm) needle.Never useabeveled, pointed, or
taperedneedle.
Needle specificationsarenot criticalwhenusingaLoopFiller Port to
load the sample loop.However, it is important to tighten theneedleport
fittingaround theneedle if usinga syringeneedlewitha slightly smaller
diameter than0.7mm (0.028”).
If the loadingmethodused iscomplete-filling, a syringewithout aneedle
canbeused.A syringefittedwithaNeedlePortCleaner canbeusedwith
a front-loadingvalve (Figure2A) orwithaLoopFillerPort (Figure2B).
Needleport accessoriesare listedon thispage.
Figure1
Asquarecutneedle: (A)
stopsagainst thestator faceassembly;
Thetipofapointedneedle
(B) slips intothestator faceandthetip
breaksoffas thevalverotates
B
Rotor seal
Needle seal
Needle
Needleport tube
Stator faceassembly
A
Rotor seal
Needle seal
Needle
Stator faceassembly
Needleport tube
A
Figure2
(A) SyringefittedwithNeedlePortCleaner (Part #7125-054) loadinga front-loading
valve (model 7725); (B) loadingaLoopFiller Port (Part #7012)
B
Adapters for SyringeNeedles
