Post-Purge Time - ABB GAA330-M Operating Instructions Manual

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Post-purge time

Post-purge time duration
Guide for the post-purge time
Example
Adjustment of the post-purge time
GAA330-M EMISSION MONITORING SYSTEM
The post-purge time at the end of the back-purging procedure must be
such, that the complete pneumatic system is flushed with the actual sample
gas and the analyzer gets time to take over the actual measuring value
again. The needed post-purge time depends on the respective layout of the
system (i.e. the length of the sample gas line) and will have to be adjusted
individually. A post-purge time of 150 s is factory-set.
A guide for the needed post-purge time is given in the table below. Please
add the times for the pneumatic system, the analyzer and the sample gas
line.
Pneumatic system without sample gas line
plus analyzer Uras26
plus for each 10 m sample gas line I.D. = 4 mm
plus PFE2/PFE3 with probe tube 40, length = 1 m
For an analyzer system with filter unit PFE2/PFE3 and 15 m sample gas line
at 60 l/h sample gas flow and 100 l/h bypass flow the post-purge time is
calculated as follows:
Post-purge time = 27 s + 20 s + 1.5 x 5 s + 45 s = 99.5 s
To adjust the post-purge time the parameters of the AC500 program must
be changed. Please contact ABB service.
| OI/GAA330-M-EN REV. C
Response time (3 x T90, approx.)
27 s
20 s
5 s
45 s