Hanna Instruments HI 8614N - Manual (Page 8)

14 15
FOR HI 8615L ONLY
The HI 8615L are factory calibrated, and the displayed values are
referenced to the 4-20 mA loop current. Under normal application,
adjustment on this module may not be necessary. If routine check is
required, the following procedures shall be performed.
• Follow the above procedure for HI 8615 (see page 13).
• Simulate a 12.00 mA loop current for the transmitter (i.e. 0 mV
at Electrode input) and check display reading.
• Simulate a 20.00 mA loop current for the transmitter (e.g.
+1000 mV for HI 8615L at Electrode input) and check display
reading.
• Connect the ORP electrode to the module and immerse the tip of
the electrode into the beaker of HI 7020 ORP solution and check
that the ammeter reading lies between 13.6 and 14.2 mA for
HI 8615, or the instrument reading is between 200 and 275mV
at 25°C (
HI 8615L only).
• Only if the reading lies outside this
range, adjust the slope adjustment
trimmer on the transmitter to reflect
a reading within this range.
• If the reading lies outside this range,
adjust the slope adjustment trimmer
on the transmitter for a reading just
within this range.
The unit is now calibrated.
A complete calibration of the transmitter
module is advised periodically.
This calibration procedure requires the HI 8427 or the HI 931001 pH
and ORP simulator to simulate the ORP electrode.
HI 8427 or HI 931001 produce a known signal into the system so
that the faults of the system can be isolated.
• Connect the ORP transmitter to the simulator.
• Set the simulator to 0 mV and adjust the offset trimmer to read
12 mA on the ammeter or 0 mV on the HI 8615L display.
• Set the simulator to 350 mV and adjust the slope trimmer to
read 14.8 mA for HI 8615 on the ammeter or 350 mV on the
HI 8615L display.