YOKOGAWA EXAxt ZR22G, User Manual, Page: 155 / 211

<10. Other Functions>
10-8
IM 11M12A01-02E 16th Edition : Mar. 19, 2020-00
10.4 Blow Back
This section explains the parameter settings for performing blow back.
10.4.1 Mode
There are three modes of blow back operation: no function, semi-automatic, and automatic.
Blow back is not performed when the mode is set to “No function”. In “Semi_Auto” mode, blow
back can be started by key operation on the display or by a contact input signal, and then
sequentially performed at a preset blow back time and hold time. In “Auto” mode, blow back
is automatically performed at preset intervals. For “Semi_Auto” or “Auto” modes, blow back is
performed. The following restrictions apply:
When “No function” is selected:
Blow back is not performed
When “Semi_Auto” is selected:
Semi-auto blow back can be performed. (Blow back does not start at Auto blow back start
time.)
When “Auto” is selected:
Blow back can be performed in either “Auto” or “Semi_Auto” mode.
<Setting Procedure>
(1) From the Basic panel display, touch [Setup] key; on the Execution/Setup display which
appears, select “Maintenance”.
(2) On the Maintenance display, select “Blow back setup” and the Mode selection pull down
allows you to select between “No function”, “Semi_Auto” and “Auto” (see Fig.10.8).
Enter
No function
Semi_Auto
Auto
Mode:
Blow back setup
F10.9E.ai
Figure 10.8 Blow back setup Display
10.4.2 Operation of Blow back
Figure 10.9 shows a timing chart for the operation of blow back. To execute blow back with a
contact input, use a contact input with an ON-time period of one to 11 seconds.
Once blow back starts, a contact output repeatedly opens and closes at an interval of
approximately 10 seconds during the preset blow back time. After the blow back time elapses,
the analog output remains held at the preset status until the hold time elapses (refer to Section
8.2, earlier in this manual).
As the hold (output stabilization) time, set the time until the sample gas is returned to the sensor
and output returns to the normal operating conditions, after completing blow back operations.