Burkert Type 8620 - Manual (Page 131)

mxCONTROL Type 8620
Page 131
14.9 Time scheduled Biocide Dosing
(BIOCIDE_DOSING)
The Biocide Dosing Module is designed for a fully automated dosing regime within 14 days.
These modules are
explained below.
Figure 68:
BIOCIDE_DOSING
Real Time Clock (RTC)
Accurate timing is maintained by a battery backed-up real time clock. The real time clock can be
adjusted by the operator.
Channel 1 and Channel 2
Biocide dosing is controlled by a dual channel 14-day timer, programmable during the parameteriza-
tion process. Both channels actuate a separate output (relay). Accurate timing is maintained by the
real time clock
.
It is possible to set up to 8 individual biocide dosing events per day per channel. That means, the
start time of dosing and the dosing duration (Tdose) can be set individually for each dosing event.
The delay between main dosing and post dosing (Tm1) together with the delay after post dosing
(Tm2)
are the same for each dosing event of the same channel – refer also to Figure 69.
If only 1 channel is required for an application, channel 2 can be disabled via configuration file (set
channel mode ChMode from "dual" to "single").
Channel Output in Automatic Mode
For biocide dosing a 2/3rd -1/3rd strategy is implemented. When the dosing process begins, the
dosing pump is activated first for a period of 2/3rds of the dosing time (Tdose). The remaining 1/3rd
of the dosing time is provided for post-dosing after a delay (Tm1). Once the dosing process has been
completed, the control of the bleed valve is not immediately handed back to the conductivity
controller - another delay (Tm2) prevents the conductivity controller from a possible opening of the
bleed valve following immediately. A further timer (Tm2) delays conductivity control for an additional
period, further enhancing the contact time and hence effective kill time of the biocide.
The control of the dosing pump during the dosage can be adjusted for each channel separately via the
parameter „CMD on“.