wtw OxiTop C - Page 45

OxiTop
®
Control OC 100 GLP/TOOLS
ba31114e06 06/2012 45
The
AutoTemp function
The AutoTemp function is made up of the adaptation phase and the test
phase.
Adaptation phase
The phase without evaluation of the pressure process. The duration of the
adaptation phase is defined for the various measuring times according to the
table. The adaptation of the microbiology to the characteristics of the sample is
made in this phase and small temperature deviations, too high and too low
temperatures of the sample, can be compensated for. The measuring system
is zeroed after the adaptation phase has expired.
Test phase
The phase in which the further pressure process direction in the sample bottle
is checked. The test phase is defined for the various measuring times
according to the table. In this phase, the continuing temperature deviation can
be compensated if the temperature of the sample is too low.
Sequence of the test
phase:
With a further drop in pressure (consumption) or constant pressure after the
adaptation phase, the pressure value at the end of the adaptation phase is the
starting point of the measurement.
On a further increase of pressure following the adaptation phase (the sample
is still too cold), the turning point of the pressure process at which the pressure
increase changes into a pressure drop, is the starting point of the measure-
ment. If the sample is too warm the test phase is dropped (temper the sample
according to the table on the last page).
If no starting point is found (according to the procedure given in points 1 and 2)
after the termination of the AutoTemp phase (time limit exceeded), the last
measuring point of the AutoTemp phase forms the starting point.
This means that the BOD curve in the graphical evaluation does not emerge
from the coordinate origin at the zero time point. A sample that was too cold
was started.
Switch the AutoTemp function on or off (only BOD Standard mode):
BOD measuring
time
Duration of the adapta-
tion phase
Duration of the test phase
0.5 to 23 hours Since the measurement times are very short, the sys-
tem always suppresses the AutoTemp phase here
even if the AutoTemp function is switched on in the set-
tings.
1, 2, 3, 4, 5 days 14, 28, 42, 56, 70 minutes Max. 28, 56, 84, 112, 140
minutes
6 to 99 days
in a 1 day pattern
70 minutes Max. 140 minutes