general reference
VICIAG International
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105
Glossary
Nut
The tensioningcomponentof acompression
fitting.As the threadednut is tightened into the
fittingdetail, itpushes the ferrule forward into
the tapered ferrule seat,causing it tomakeup
on the tube.
O
OD
Outsidediameter.
One-piecefingertight
Aone-piecefingertightfitting isaknurled
orwingednutwith integrated ferrule. It is
convenient touse since the ferrule is retrieved
from theportwith thenut. Note: Polymer type
ferrules relyon surfacecompression to forma
seal andhold the tubeby friction.
P
Pilot
The tubingwhichextendsbeyond the ferrule
inamade-upfitting,or the integral portionof
aZRF internal reducing ferrulewhichextends
beyond the ferrule.Seealsopilotdepth,below.
Pilotdepth
The lengthof the tubingdiameter cavity
beyond the tapered ferrule seatwithinafitting
detail.Valcofittingpilotdepthsare tightly
controlled to facilitate the interchangeabilityof
componentswithout the riskof leaksordead
volume.
Pipe thread
Theexternal or internal threadsof afitting
designed toeffect ametal-to-metal seal on the
conical thread faces.This typeof fittingdoes
not“bottomout”in thedetail.Typicallyused
withPTFE tapeorother compound to lubricate
the threads;however,since thediffusion rate
of air components through thePTFE tape is
considerable,pipefittings shouldnotbeused
in systemswhere leakage ratesarecritical.
Plug
Aplug isused toblockafittingdetail ina
union, tee,cross,or valve.
R
Reducing ferrule
A ferrulewhichallowsa smaller tube tobeused
inafittingdetail designed for a larger tube.
Caution shouldbe taken if standard reducing
ferruleswithout integral pilotsareused,since
deadvolumemaybecreated in thefittingpilot
depth.
Reducingunion
Afittingwhich joins two tubesofdifferentODs.
Theboreof thefitting should typicallymatch
the IDof the smaller tube.
S
SFE
Supercritical FluidExtraction.
Anextraction techniqueusingafluid in its
supercritical stateas theextractionmedium.
Some liquidsandmixturesmaintainedabove
acritical temperatureandpressureexhibit
propertiesofboth the liquidandgasphasesof
theelement.Thesearedefinedas supercritical.
CO
2
isacommon supercritical fluid.Extreme
cautionmustbeusedwith supercritical CO
2
,
sinceuncontrolledexpansion (leaks) canbe
veryhazardousdue to the substantial stored
energy.
SFC
Supercritical FluidChromatography.
Ananalytical techniqueusinga supercritical
fluid (seeSFE) as themobilephase/carrier.
Standardbore
Aborewhichwas chosenas the standard for a
particularfitting, typicallybasedon themost
common tubing IDusedwith thatfitting.
ferrulemade
upontubing
fittingbody
pilot
tubing
