Manual

12
IM 11M6D2-02E-A
3) If the calibration interval is shorter than the sum of the
stabilization time plus calibration time, the second calibra-
tion start time will conict with the rst calibration. In such a
case, the second calibration will not be conducted. (When
both zero and span calibrations are to be performed, the
calibration time is double that required for a single (zero or
span) calibration).
4) If the (Calibration) Interval is et to DD: 00, HH: 00 then
auto Calibration will not be performed.
5) If the start date is set before the current date, then Auto
Calibration will not start.
6) [Cal. Time] of [Calibration timing] display will be equalized
to [Check time] of [Semi-auto ind. Chk] display
other
commands
Purging
the
channel
Man. Cal.
SemiAuto
AutoCal
X
X
Wait
X
X
Wait
X
X
Wait
X
X
Wait
X: Cannot perform calibration
Wait: Wait until other command finishes before starting calibration
X
X
Wait
X
X
X
X
X
X
X
X
X
Other
channel
CAL
Indication
check in
other channel
Blowback in
other
channel
Maintenance CAL chan.
in warmup
status
CAL chan.
in ERR
status
CAL chan.
now
disabled
Table 7.1 When Auto Calibration conict with Other Commands
VIII. MAINTENANCE
Because of the AC4/AC8 unit’s simplied construction, no
routine maintenance is required, other than replacing the
calibration gas when necessary. When cal gas cylinders are
changed refer back to Section 7.1.2 Calibration Setup Pro-
cedure. Failure to perform the Calibration Setup Procedure
upon replacing cal gases will result in an error in the zero
correction values. When changing gases it is also necessary
to check the zero gas ow rate.
It is recommended that periodic inspections are performed
to insure a sufcient supply of calibration gases when the
pressure switch input is not used. Also, periodic checks
verify that the ow rate of the calibration gases, to the indi-
vidual oxygen detector probes have not been accidentally
changed. It is important that the zero gases ow at a rate of
0.6 LPM (600mL/min.), while the reference air (instrument air)
ows at 0.8 LPM (800mL/min).
Refer to Section 10 of this manual for a listing of spare parts
for the AC4/AC8.
IX. TROUBLESHOOTING
9.1 TYPICAL CALIBRATION PROBLEMS
1) Gas does not flow to the probe.
• If reference air is used, then the reference air ow meters
should show 0.8 LPM at all times. If the reference air ow
meters do not show 0.8 LPM, then conrm that the instru-
ment air has been turned on by checking the regulator gauge
(10to 35 psi).
• Conrm override screws are in the NORMAL mode for the
block solenoid and all channel solenoids.
• Turn block solenoid to the manual position. Cal gas ow
meter should show 0.6 LPM. If cal gas ow meter shows 0
LPM, turn the black knob on the ow meter to open the ow
meter. Set ow rates for all probes as according to proce-
dures shown in Section 5 of this manual.
2) Flow meter will not go to 0.8 LPM for reference air.
• Turn the ow rate adjustment knob only, NOT the override
screw.
• Only one channel should be in the manual override posi-
tion. All other probes should be in the normal position.
• Check the pressure regulator at the gas source. If the
pressure is below 14 psi, increase pressure in increments
of 5 psi, and adjust reference ow meters. DO NOT in-
crease pressure to greater than 35 psi. If more than 35 psi
is needed, attempt to move the calibration box closer to the
probes, without compromising safety or the ambient operat-
ing temperature of the auto cal unit.
• Tubing outside diameter (O.D.) should not be greater than
1/4” .Tubing runs should not be in a T position, and should
remain separate for each probe.
• Check for leaks at compression ttings. All NPT ttings
should have Teon tape on the threads to prevent leaks.
3) Flow meter will not go up to 0.6 LPM for cal gas.
• Same solution as above, except make adjustment to the
cal gas ow meter.
4) Wrong gas flowing to the probe.
• Conrm that gases are plumbed correctly at the left side of
the calibration unit.
• Turn the override screw on the three-way solenoid to the
normal position.
• Perform a cal check in semi auto calibration mode. (See
Section 5).
IMPORTANT
When performing an actual automatic or semi automatic cali-
bration, and a calibration alarm occurs, it is necessary to reset
the channel. Instead, recalibrate the channel to remove the cali-
bration alarm. For additional troubleshooting procedures, refer
to the AV550G manual, Section 12.