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13. One-touch zero/21vol% adjustment
(Zero adjustment for CDS-7, CHS-7 and 21vol% adjustment for COS-7)
Take the steps in the table below, to perform one-touch zero/21vol% adjustment once the
specified period of time passes after turning on the main unit. Repeat the one-touch
zero/21vol% adjustment to increase the accuracy.
Sensor unit type
Timing for
1
st
adjustment
Timing for
2
nd
adjustment
Steps
Toxic gas:
CDS-7
30 minutes after
powering-up
24 hours after
powering-up
Set the maintenance switch to MNT1
or MNT2. Press the ZERO button.
Oxygen gas:
COS-7 (25vol%)
Set the maintenance switch to MNT1
or MNT2. Press the SPAN button.
Combustible
gas: CHS-7
One day after
powering-up
7days after
powering-up
Set the maintenance switch to MNT1
or MNT2. Press the ZERO button.
Procedure
(1) Set the maintenance switch to MNT1 or MNT2 position. Refer to 7-5.
“Maintenance Mode
Setting/Operation
” for more information.
Depending on the environment, it may take longer than the expected 24 hour/7
day period (see above) for the base line (zero or 21vol%) to be fully stabilized.
For COS-7 oxygen sensor (FS: 50vol%), one-touch 21vol% adjustment is not
possible. However, if 21vol% adjustment is needed, refer to
“PS-7 gas
detector’s operation manual for administrators” for the procedure (separate
document).
NOTE
Perform zero/21vol% adjustment in clean air. Inaccurate gas concentrations will be
indicated if the zero/21vol% adjustment has been done in a contaminated gas
atmosphere.
When switching the maintenance switch from MNT1 to MNT2 or vise versa, the gas
detector briefly enters the normal operation mode. If switching is done while an alarm
condition exists, an alarm signal will be output. If the alarm contacts/open collector are
used to operate the interlocks of the external devices, release the interlocks beforehand,
as needed to prevent a possible activation of the interlocks during switching the
maintenance switch.
Set to MNT or MNT2
Lift the cover flap open.
