3-24 Using the Waters 515 Pump
6. Set the flow rate, high-pressure limit, and low-pressure limit at the data
system or external controller. For example, if the pump is connected to a
Waters Millennium
32
system through a PCM, the pump parameters are
part of the instrument method in the Millennium
32
software. See the
documentation that comes with your data system or external controller.
7. Start the run from the data system or from the external controller. The
pump starts and the Flow area of the pump display reads Flow. To
immediately Stop the pump at any time, press the Run/Stop key.
Tip: If your 515 pump is connected to a Waters 680 Automated Gradient
Controller, and you power on the controller with the 515 pump running in the
Remote mode, you may hear the pump operate briefly. This is due to a
spurious signal from the controller when it is powered on. To avoid this
situation, power on the controller before you power on the pump.
Changing parameters during a run
You can change pump parameters while the pump is running in either Local
or Rem mode. To change parameter settings while the pump is running, follow
the steps in “Editing or entering parameters in local or remote modes” on
page 3-12. Note that changing the Flow parameter at the pump when the
pump is in the Rem mode does not change the pump flow rate (the flow rate
set at the external control device supersedes the rate set at the pump). See the
table titled “515 pump operating parameters” on page 3-7 for more details
about the Flow, HPL, and LPL parameters in Rem mode.
Adjusting for eluent compressibility
Eluents exhibit different compressibility characteristics in response to
changes in pressure. The change in compressibility can result in changes in
flow rate. The Comp parameter allows you to easily adjust for the change in
delivered flow resulting from eluent compression and system expansion at
higher pressures.
The Comp parameter for the 515 Pump is preset to zero at the factory using
degassed methanol as an eluent. This section describes how to adjust the
Comp parameter for use with other eluents. The procedure describes how to
measure flow rate using a volumetric flask and a stopwatch. An alternate
method would be to use a calibrated flowmeter.
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