valco fittings
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techtip
Filteringcapabilitycanbeadded toaunionby insertinga screenor frit into itbeforemaking
up thefittings. However,whenafittingdetail hasa screenor frit in it, thepilotdepth is
reduced,so that the ferrulemakesupcloser to the tubeend than itotherwisewould. If
that tube isused inanyotherValcofitting, itwill introduceunswept volume. Ourfilter
design takes this intoaccount,allowingourfittings to remain truly interchangeable.
Filters . . . . pages50-52
Fritsand screens . . . 53
Unions
tubingmadeup inaunion
Tubingmadeupwithafrit
lengthsof
pilotsare
different
withoutfrit
withfrit
frit
Unions join twopiecesof tubingof the
sameOD. Select theunionwith the
bore thatmatches the IDof the tubing.
If the IDsaredifferent,choose the
unionwithaborewhichmatches the
smaller tubebore. Standardmaterial
is300 series stainless steel.
Internal
unionshave female
threadsandafittingdetail for zero
volumefittings. Thenutshavemale
(external) threads.
External
unionshavemale threads,
requiringanutwith internal threads.
External/internal
unionshavemale
threadsononeendand female
threadson theother, for connecting
a standardzerodeadvolumefitting
toanexisting tubewhichalready
hasanexternal nutmadeupon it.
Bulkhead
versions canbemounted
throughan instrumentpanel orona
bracket. Thefittingbody isundercut
so that itbites into thepanelwhen the
mountingnut is tightened,eliminating
theneed for a lockwasher. AnO-ring
canbe installedbetween thebodyand
thepanel toallowoperation inpurged
environments. Typically themounting
nutgoes inside the instrument,so
that the long threadedportionwill be
outof sight. In theexternal/internal
bulkheadunions, themountingnut
ison the sidewith theValco internal
fitting.
Internal fittingsarealmost always the
bestwith tubingof 1/8"ODor smaller.
Theymakea stronger connectionand
offer the lower volumenecessary for
highperformance instrumentation.
Also,because1/16" external fittings
havevery thin,easilydistortedwalls,
theyarenot asdurableas1/16"
internal fittings. In sizes larger than
1/8",external fittingsaregenerally
easier tomakeupbecauseof less
thread friction.
0.25mm = .010"
0.50mm = .020"
0.75mm = .030"
1.0mm = .040"
1.5mm = .060"
2.0mm = .080"
4.6mm = .180"
6.0mm = .236"
6.4mm = .253"
7.0mm = .275"
10.0mm = .400"
27.0mm = 1.08"
1/32" = 0.8mm
1/16" = 1.6mm
1/8" = 3.2mm
1/4" = 6.4mm
3/8" = 9.5mm
1/2" = 12.7mm
CHROMalyticTECHnologyPtyLtdAUSTRALIANDistributors e-mail:
: 03 97622034
