21
Calibrating and Sampling in Constant Pressure Mode
— Multiple Tubes
For use with multi-port adjustable low flow tube holders only.
Calibration
Before use, allow the pump to equilibrate after moving it from one temperature
extreme to another.
1. Ensure the pump has run for five minutes before proceeding with calibration.
2. Set the pump to enhanced display and Constant Flow mode (
see pages 12 and
13
). Remain in these modes until ready to calibrate.
3. Connect the pump to an Adjustable Low Flow Tube Holder (
see Optional Ac
-
cessories, page 27
). Use a screwdriver to turn all the flow adjust screws counter-
clockwise until they are flush with the tube holder surface.
4. Label all tubes and ports (e.g., tube #1, port A).
5. Insert the first opened representative tube (#1) into the first port (“A”), etc. Place
unopened tubes in any unused ports to “seal” them. This is essential to obtain
correct results.
6. Set the desired flow rate to a primary standard calibrator (
see pages 15 and 16,
Steps 5 through 11
) as specified by the method for tube #1 in port A. Record the
flow rate.
See cautions below.
7. While the pump is in RUN, press the
button to scroll to Constant Pressure
reading (ins or mm). Record the back pressure for that tube. Press [
] to place
the pump in HOLD.
8. Repeat Steps 5 through 7 for each port to obtain the back pressure for each
representative tube.
All empty ports must contain
unopened
tubes during calibration and sampling.
When performing multiple-tube sampling in Constant Pressure mode, the flow
rate must be set as low as possible. The sum of the flow rates cannot exceed
100 ml/min for back pressures from 10 to 20 inches of water; the sum of the
flow rates cannot exceed 200 ml/min for calculated back pressures less than
10 inches of water.
Advanced Operation
