Metrohm 796 Titroprocessor - Manual (Page 120)

7.7 KFC Karl Fischer conditioning
796 Titroprocessor, Instructions for use 114 114
7.7 KFC Karl Fischer conditioning
Application:
The KFC modes are independent titration modes which can be used in
preparation of a
KFT mode. They are suitable for rapidly bringing a titration
sample to a certain measuring value (endpoint).
Their typical feature is controlled reagent dosing depending on the control
difference (actual value – endpoint) with the aim of reaching the preset value
as quickly and accurately as possible. Overshooting is virtually eliminated.
No provision is made for the representation of curves or carrying out calcu-
lations.
Reagent addition and switch-off criteria correspond to those of the KFT
modes.
7.7.1 Control of the conditioning mode
Conditioning is normally carried out in the background, i.e. as soon as a
conditioning mode has been started the 796 Titroprocessor can carry out
other commands. A conditioning process also remains active even when a
determination has been finished, provided that it has not been explicitly ter-
minated; see below.
A conditioning mode carried out in the background is controlled by the
WAIT_C command (see page 209f). This checks whether the conditioned
state has been achieved and, if necessary, switches the conditioning mode
off.
Example:
KFC_U* KFC_U* ДДДДДДДДДДДДД ДДДДДДДДДДДДД¿ ¿
... | ... |
... KFC_U*
... KFC_U*
... ...
... ...
WAIT_C ...
WAIT_C ... ДДДДДДДДД ДДДДДДДДДЩ Щ
ASK ASK
KFT_U*
KFT_U*
The WAIT_C command synchro-
nizes the background conditioning
process with the method being car-
ried out in the foreground. The
WAIT_C command interrupts the
regular method run until the back-
ground process (conditioning) has
been completed.
Note! Every titration, measuring or calibration mode also terminates back-
ground conditioning. Achievement of the conditioned state is not taken into
account.
Conditioning should always be carried out with the same parameters as
were used for the sample titration (
KFT modes).
The various parameters of the KFC modes are described in detail on
pages 167 to 170.