valcovalves
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LeakTesting
The standard testmethods for cross-port andoutport leakage insurevalve
performanceatpressuresand temperaturesup to the specifications listed.
For valvesusedonmass spectrometersor forultra-tracefixedgasanalysis,
we recommendanoptional testmethodutilizingaheliummass spectrometer,
whichprovidesdataonmechanical leaksandon thosedue to seal porosityand
permeability. With thismethod,wecancertify leak ratesas lowas10
-10
cc‑atm/sec.
Pleaseconsult the factoryprior toordering,since theminimum leak ratewill vary
widelydependingonvalveconfiguration.
LeakRates for
GasSamplingValves
Theactualminimum leak ratesattain-
ablevarywidelywith sealmaterial and
valve type. Ingeneral, theacceptable
leak rates fall into three ranges. (See
chartbelow.)
Inorder to seal to less than10
-7
, the
valve loading tension is increased,
which somewhat lowers themaximum
operating temperatureand thevalve
lifetime. Currently,only selectmaterial
can seal to10
-8
inmost valve styles.
ValconM rotormaterial canseal to10
-10
,
buthasa temperature limitof 50°C.
Not all valves canachieve these leak
rates. Asageneral rule, the larger the
valve seal andport size, thehigher the
leak rate.
optionalleak
testing
withHeliumMass
Spectrometer
Toorder avalvecertified
tohavehelium leak rates
less than10
-7
cc‑atm/sec,
add the suffix "Z" to the
valveproductnumber
and$175 to theprice.
Certifiedvalvesare
suppliedwithgold-plated
stainless steel ferrules.
Wecangenerally tell
youwhat leak rate
ispossibleprior to
manufacturing thevalve.
TestMethod for
LiquidSamplingValves
The standard testmethod for liquid
valves isapressuredropover time for
bothcrossport andoutport leakage,
using isopropanol at the specified
testpressure. This test isdesigned
toensureproperperformanceat the
specification limit.
rangesforacceptableleakrates
10
-4
to10
-5
cc‑atm/sec
Commercialuse
Notnormally soldbyVICI
10
-6
to10
-7
cc‑atm/sec
GeneralGCuse
Standard tensionandcomponents
10
-8
to10
-10
cc‑atm/sec
Ultra tracegasanalysis
(ppb range)
Higher tensionand specially
processed stator and rotormaterial
CHROMalyticTECHnologyPtyLtdAUSTRALIANDistributors e-mail:
: 039762 2034
