QuickSplit™ Fixed Flow Splitters
Unlike conventional splitters that use long lengths of capillary tubing, the ASI QuickSplit™ Fixed Flow Splitter uses two compact fluid resistor elements which are designed as cartridges for easy replacement. ASI fluid resistors are analogous to resistors used in an electrical circuit. Resistance values (L) are rated in PSI/mL/min. Because of the extremely low internal volume of the fluid resistors, the solvent composition in both resistors at any instant in time is the same, and therefore viscosity changes associated with gradient runs do not impact the split ratio.
QuickSplit™ Fixed Flow Splitters provide a fixed split ratio with extremely low dead volume. Delay volume on the low flow rate side is as low as 100 nanoliters, depending upon the resistor cartridge selected. The split ratio is not affected by changes in solvent viscosity or pressure, and is extremely stable and reproducible. The interchangeable fluid resistors are available in a wide range of values which make it possible to create split ratios from 1:1 to as high as 20,000:1.
The flow path of the QuickSplit™ Fixed Flow Splitter contains two fluid resistors that form a parallel flow path. Both low and high flow rate streams pass through fixed resistor cartridges. The ratio of these two resistors creates the split ratio. To understand how the QuickSplit™ Fixed Flow Splitter works it helps to look at a diagram, Figure 7, of the fluid resistors in relation to the flow paths and how a split ratio is calculated.
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Schematic flow diagram of the QuickSplit™ Fixed Flow Splitter
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Low Flow Rate - Q2 | ||||||
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| High Flow Rate - Q1 | ||||||||
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Figure 7
Since the flow rate is indirectly proportional to resistance, changing the resistance in either flow path results in a change to the split ratio. Changing resistance is accomplished by exchanging the fixed fluid resistor cartridges with a resistor set that has different resistor ratings.
The QuickSplit™ Fixed Flow Splitter is shipped with resistors installed that deliver the nominal stated split ratio. The split ratios have a tolerance range of +/- 10 %. The exact split ratio is measured at ASI and is stated on the certificate shipped with the splitter. The input flow rate can be adjusted to compensate for the tolerance in split ratios. For instance, a 10 % increase in input flow rate will result in a 10 % increase in flow at both the low and high flow channels. Flow rate and viscosity changes will change the backpressure generated by the splitter, but will not affect the actual split ratio. The QuickSplit™ Fixed Flow Splitter is shipped configured for either post-column or pre-column applications.
