Dionex AXP/AXP-MS Manual
EVENT 1 (Pole), EVENT 2 (NC), and EVENT 3 (NO) terminals.
When the pump stops because the sensed pressure exceeds the set
pressure limits or due to a motor stall fault, the connection between the
EVENT 1 terminal and the EVENT 2 and EVENT 3 terminals is
affected. EVENT 2 is Normally Closed (connected to EVENT 1) until
a fault occurs, when it opens. VENT 3 is Normally Open (not
connected to EVENT 1) until a fault occurs, when it closes.
7.2.1.1 Upper and Lower Pressure Limit Ranges
The pressure sensing transducer provides accurate, wide range
pressure monitoring. Because of the sensitivity of the transducer, the
zero reading may shift up to 0.1% of the full-pressure scale over years
of operational use. The user should also be aware that the resistance to
flow of the fluid being pumped through the tubing and fittings may
cause the pressure to vary with the flow rate and the viscosity of the
mobile phase employed.
If absolute accuracy is needed for the pressure safety limits:
1. Disconnect the column from the pumping system and operate
the pump with the mobile phase and flow rate to be used in the
analysis. Observe the resulting pressure displayed on the pump
readout. The column will cause a pressure reading that adds to this
basic reading due to system flow resistance.
2. Set the upper limit shutoff to a pressure equal to the basic
reading plus the safe operating pressure for the column to be used.
For example, if the basic pressure reading (without the column) is
7 psi and the safe limit for the column is 25 psi, set the maximum
pressure limit to 32 psi or less.
3. If the mobile phase or flow rate is changed, reset the pressure
limit as appropriate.
4. Note that a lower pressure limit is available to prevent
continued operation in the event of a leak. Be sure to set this
pressure limit to a pressure higher than the basic pressure; this will
ensure that the reduced pressure is sensed.
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