YL Instruments YL9100 HPLC, User Manual

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YL9112 Isocratic Pump
2-2. Operation
There are essential parameters on the pump as like flow accuracy, precision, and reproducibility to get
the reliance of analysis data and low detection limit. YL9112 isocratic pump uses high pressure resistant
dual pump head, controls microprocessor to monitor the phase of cam to remove pulse, so fulfill the
necessities of solvent delivery pump.
Diaphragm pulse damper reduces pulse from the cam operation more than 90% between low and high
pressure range by internal elastic body of damper, and also works well as a mixer for gradient elution. The
elastic body of Diaphragm pulse damper improves flow accuracy through compression, expansion
procedure to make variance of kinetic energy by flow constant. The amount of contact solvent with pulse
damper is around 1.5ml at 3000psi, which ensures that flow path is completely cleared away.
Y
L9112
YL9112 isocratic pump was designed so that integrated flow rate may realize no-pulse operation using
specially designed cam. However, pulse incapable of being neglected is caused actually due to
compressibility of mobile phase proportional to pressure and elasticity of high pressure seal, so the pump
is controlled in real time so that occurrence of pulse proportional to pressure may be depressed. Control
method of the Pump uses supervision of pressure and control of location simultaneously, so it has
advantage to improve precision and accuracy of flow rate without being affected by range of pressure and
flow rate. There is a part for microprocessor control to realize various function of pump including
stepping motor control. Stepping motor control processor operates motor as a micro step, so can achieve
constant motor speed at low flow rate with low noise.
Operation mechanism is for transmission of kinetic energy from step motor to piston. This mechanism
includes specially designed cam, stepping motor, carrier, carrier housing, and phase sensor.
2-3. Compressibility compensation
Most of pumps for HPLC analysis are used at high pressure. However, pulse occurs in high pressure
due to compressibility of liquid and elasticity ratio of seal, so flow rate is also reduced. Occurrence of pulse
due to this reduces precision and accuracy of pump flow rate, so compensation is necessary for this.
YL9112 isocratic pump monitors actual pressure and calculates compensation value for this;
compressibility compensating operation to control angular velocity of cam with this value reduces
occurrence of pulse flow remarkably as well as improves accuracy of flow rate largely .
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