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 1, of
the fluid resistors in relation to the flow paths and how a split ratio
is calculated.
Schematic flow diagram of the
QuickSplit™
Fixed Flow Splitter
 |
|
 |
Low Flow Rate - Q2 |
| Input Flow - Q |
|
| |
High Flow Rate - Q1 |
| |
| L1 |
= Fixed fluid resistor (resistance value
varies depending on cartridge rating) |
| L2 |
= Fixed fluid resistor (resistance value varies depending on cartridge rating) |
| R |
= Split ratio = Q1/Q2 = Resistance ratio = L2/L1 |
|
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.
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