21
Refer to Fig. 3.4
Note:
Enter temporary values for the settings when the
flow rate compensation value is unknown.
Use a volumetric flask (having a capacity equal to the amount
of solvent delivered in five minutes or longer) and a
stopwatch.
When measuring the flow rate, connect a back pressure coil
(tubing having a 0.1 or 0.25 mm i.d.) to the outlet port to
obtain a back pressure of 0.5 ~ 1.0 MPa.
Note:
Slight back pressure (0.5 ~ 1.0 MPa) is required in
order to maintain proper pump head operation and
prevent the apparent flow rate from increasing due
to siphoning. This setup is still considered to have
no back pressure.
FLOW COMP
F F
F
=
+
−
×
128
10
0
0
3
F
0
: Set flow rate
F: Measured flow rate
The above equation can be rearranged as follows:
F
F
FLOW COMP
=
× +
−
0
3
1
128
10
(
)
Therefore, when the FLOW COMP value is increased
(decreased) by 1, the flow rate increases (decreases) by
approximately 0.1%.
Input the FLOW COMP value calculated above.
Figure 3.5 Flow Rate Calibration Step 1
3.3.4 Flow rate calibration: Step 2 (with back pressure)
Flow rate calibration must be performed both with and without back pressure.
Perform the operations described in the present section only after performing the
operations described in Section 3.3.3.
When the flow rate calibration value is unknown (Case 3 in Section 3.3.1),
temporarily set PRESS COMP to 4.7. Set the FLOW COMP to the value obtained in
Section 3.3.3 then calibrate the flow rate using the procedure shown in Fig. 3.6.
FLOW COMP: 118
PRESS COMP: 4.7
No
Yes
Enter the temporary flow
rate calibration values
Measure the flow rate
Calculate the FLOW
COMP value
Flow rate
compensation
screen
Measure the flow rate
Has the required flow rate
accuracy been attained?
Flow rate calibration
Step 1 completed