OPERATION
Initial check of the PMH-2.
After the instrument is properly installed, an electrode or simulator
connected and the power applied, the “RUN” LED will light up. The output
relay may latch depending on the signal input. Sweeping across the range
with a simulator will activate the relay and “RELAY OUTPUT” LED at the
programmed setpoint.
Calibrating the PMH-2 with a simulator.
The operator should be familiar with the different effects if OFFSET and
SLOPE calibrations are carried out. Offset adjustments increase or de-
crease the reading regardless of the absolute measured value. pH7 is a
prefixed iso-potential and increasing the slope always moves the reading
away from pH7. Readings below pH7 therefore decrease in the displayed
value. Readings above pH7 increase in the displayed value. (Fig.6)
OFFSET calibrations should be carried out first, however offset and
slope calibrations can be performed separately and need not be done
consecutively.
Set the simulator to pH 7.00‘
PUSH’ and ‘Rotate CCW’ to go to CAL. ‘PUSH’ turns on the offset LED.
‘PUSH’ again, the offset LED now flashes and the display shows “live” pH
FIG. 5
THE DIFFERENT EFFECTS OF OFFSET AND SLOPE.
PMH-2 Instruction manual
PAGE 19
