126
VALVES
ChoosingaRotaryShearValve
Evaluating some simple variableswill assist you in choosing thebest
valve for your needs.
Identify theOperatingPressureof Your Instrument
orApplication
Valves aredesigned to repeatedlydeliver specific fluids todifferent
locations in a fluidic circuit. Achieving fluidic precision at 15,000psi
requiresdifferentvalve-design featuresthanwhat’srequiredtoachieve
fluidic precision at 100psi. Awide variety of variables such as valve
architectures, metals, polymers, coatings, actuation speeds, and
manufacturing techniques have been tested to achieve the fluidic
accuracyandprecisionrequired forthe fullarrayofpressureconditions
in life science applications. In this catalog, wedefine four separate
pressuregroupings:
Identify theRangeof FlowRates inYour System
Because Rotary Shear Valves have been used most often in
chromatography systems, certain flow rate ranges have evolved
functionally. However, these ranges can apply to any system, not
just chromatography:
XX
Micro/NanoScale—flow rates less than100µLperminute
XX
Analytical Scale—flow rates from100µL to10mLperminute
XX
Prep (orSemi-Prep) Scale—flow ratesgreater than10mLperminute
DecideWhat YouWant theValve toDo
In this chapter RotaryShear Valvesperform three functions:
XX
Switchingoneormore flowpaths to adifferent destination
under pressure
XX
Injection into a flowing streamunder pressure
XX
Selection/distributionof a varietyof system liquids bymeans
of a commonport
XX
Readmore about valve functions onpages 128–129
Up to 15,000psi (1,035bar)
UHPLC/Fast Chromatography
Up to 6,000psi (410bar)
HPLC
Up to 1,000psi (69bar)
UpchurchScientific
®
Up to 125psi (8.5bar)
LowPressure/AtmosphericPressure
IdentifyWhether YouWantAutomatedorManual Control
Anautomatedvalveoffersmoresophisticated functionality.Choosean
automatedvalve if theapplication requires fast, consistentflow-stream
switching.Someotheradvantagesofautomatedvalves includecontrol
options (PC- or instrument-triggered), higher torqueoperation, valve-
position feedback, or very small flowpaths.
Choose amanual valve if your application involves low frequency
of use, demands operator control, or involves injection of smaller
sample volumes. (Seepage 129 formore on SingleMode vs. Dual
Modeoperation.)
Identify theChemical CompatibilityRequirementsRelated
toYour Fluids
Consulting thechemical compatibilitychart in theTechnicalResources
sectionat thebackof The IDEXHealth&ScienceLaboratoryProducts
cataloghelps identifywhatvalvematerials touse—andavoid—inyour
application. You canalsofindChemical Compatibility informationat
IdentifyFluidicConnectionRequirements inYour System
The rotary shear valves in this catalogaccommodateoneormoreof
the following tubingouter diameters: 1/8”, 1/16”, or 1/32”.
ValveOverview
