Manual Controls

The PM-90 pump can be controlled from its front panel as detailed below, or by the pump module of ChromGraph Control software.

 

 

KEY FUNCTIONS

  Move the cursor left and right within a line.
  Increase or decrease a numerical value within a line.
  Advances to the next input line ” use this key to quickly navigate and review the two screens.
  Sets the pump to operate at a flow rate of approximately 5 mL/min to aid in priming the pump or purging the system of air. You must press RUN/STOP to begin the purge.
  Starts or stops purging after PURGE has been pressed ” when purging is stopped both plungers are moved to the full forward position for head removal or installation.
  Starts or stops the pump ” this control is used to start or stop solvent flow without turning off the main power.

CONTROLS

There are three parameters involved in setting up the pump for operation:

  1. Flow Rate
  2. Low Pressure Limit
  3. High Pressure Limit

Flow Rate. A flow rate ranging from 1-2000 (PM-92) or 1-1200 (PM-91) µL/min can be selected using the + and - keys to increment or decrement the value. After selecting the desired flow rate, press the ENTER key to advance to the next screen. If the pump is currently running, the flow rate will change as new values are entered.

Low Pressure Limit. If necessary, press the ENTER key to change to this screen. Then use the + and - keys to select the Low Pressure Limit (PSI). The Low Pressure limit can be adjusted to a value between 0 and 999 PSI. Press the ENTER key to advance to the next field.

If a fitting develops a leak, or if the mobile-phase reservoir runs dry during unattended operation, the low-pressure cutoff will stop the pump as pressure drops. Proper setting of this control will avoid pump damage. When the Low Pressure Limit is set to 0 PSI this function is disabled.

If the low-pressure limit is reached, the pump will stop and the LCD will display a Low Pressure message. After correcting the problem, reset the protective circuitry by pressing the ENTER key. The pump can then be restarted by pressing the RUN key.

The low-pressure limit is enabled only after pressure exceeds its set value. Thus, you can run the pump with the prime/purge connection open (pressure will be 0 PSI) even though the low-pressure limit is set to a value such as 300 PSI. Only after the prime/purge connection is closed, and pressure rises above 300 PSI, will a drop in pressure trigger the protective circuitry.

High Pressure Limit. If necessary, press the ENTER key to change to this screen. Then use the + and - keys to select the High Pressure Limit (PSI). High Pressure limit can be adjusted to a value between 1000 and 5000 PSI. Press the ENTER key to return to the Flow Rate Screen.

It is EXTREMELY IMPORTANT that this limit be set to some reasonable value; if a clog develops anywhere in the flow stream between the pump and the detector, the high-pressure cutoff will stop the pump as pressure increases. We suggest setting the cutoff 1000 PSI above your typical operating pressure.

If the high-pressure limit is reached, the pump will stop and the LCD will display a High Pressure message. After correcting the problem, reset the protective circuitry by pressing the ENTER key. The pump can then be restarted by pressing the RUN key.

Purge. The PURGE key causes the pump to operate at a flow rate of approximately 5 mL/min to aid in priming the pump or to purge the system of trapped air. The purge plug on the manifold should be removed prior to purging the pump if a column is connected. The plug can be replaced by a luer adapter which allows a syringe to be connected to apply suction to aid in priming the pump.

To avoid inadvertant purging, the RUN/STOP key must be pressed after the PURGE key to begin purging.

Pressing the STOP key will stop purging and move both pistons to their full forward position. This is done to allow easy removal or installation of pump heads. It may take 1-2 seconds for the pump to come to a complete stop after the STOP key is pressed while purging. After the STOP key is pressed the pump will be reset to the flow rate prior to the start of the purge.

NOTE: Always allow the system pressure to fall below 30 PSI before opening the prime/purge plug on the manifold. This will prevent pressure shocks from damaging the column or pulse damper.