Calibration Procedure - Honeywell 705 Series Operating Instructions Manual

MAN0362.P65 Issue 03, Mar 01
00705M5001

5.4 CALIBRATION PROCEDURE

Note:
(1)
(2)
(3)
(4)
(5)
(6)
5. CALIBRATION
This procedure will produce an upscale output signal
which may activate alarms if fitted. Refer to the
Warnings in Installation section of the manual before
proceeding.
Allow a minimum warm-up period of 1 hour after
applying power before carrying out this procedure.
Insert a Digital Multimeter (DMM), set to read current,
in series with the 4 - 20mA line.
Ensure the sensor is in a gas-free atmosphere then, if
necessary, adjust the ZERO control for a reading of
4mA on the DMM.
Gas the sensor as instructed in Section 6 'Gassing the
Sensor'. After 5 minutes, adjust the SPAN control for
a reading of 20mA on the DMM for 50ppm H
If procedures (3) and (4) cannot be achieved, adjust
the Offset control as follows:
a. Connect the DMM, (set to read mV), between
TP2 and TP3 on the pcb (see Figure 7).
b. Adjust the ZERO control to obtain 0.000V ± 1mV
on the DMM.
c. Disconnect the DMM.
d. Adjust the OFFSET control to obtain an output
(at terminals) of 4mA.
e. Repeat steps (3) and (4), remove the gas adaptor
and allow sufficient time for the test gas to
escape.
Turn off the test gas and check that the DMM indicates
4mA. If not, adjust the ZERO control to give a DMM
reading of 4mA.
20
705 Sensor
S.
2