Metrohm 743 Rancimat Bedienungsanleitung PDF herunterladen (Seite 176)

6.1 Problems

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743 Rancimat

Problem Cause Remedy

￭ Reduce the temperature so that less sam-

ple evaporates or no sample at all. How-

ever, this can substantially extend the

measuring time. The induction time

approximately doubles by reducing the

temperature by 10 °C.

The curve shows a

step which means

that the induction

time is no longer

determined cor-

rectly.

Side reactions occur at the

start or during the meas-

urement, which cause the

conductivity in the measur-

ing cell to rise.

￭ In the method, use the option Evaluation

delay or Evaluation suppression (see

Chapter 4.5.2.2, page 64).

￭ Do not use Endpoint(s) as a stop criterion

in the method, but instead a defined Con-

ductivity (e.g. 200 µS/cm) (see Chapter

4.5.2.1, page 60). The curves can then also

be evaluated manually after finishing the

determination.

The curve shows a

step at the start of

the measurement,

which has not occur-

red in previous

measurements.

The reaction vessel cover

(5-8) and/or the tubing

(5-2) still contain residues

which are transported into

the measuring vessel

through the warm air flow

when a new measurement

is started.

￭ Thoroughly clean the reaction vessel cover

and the silicone tubing (see Chapter 4.6.5,

page 83).

￭ Replace the reaction vessel cover and the

silicone tubing from time to time.

The induction time

is not evaluated

automatically,

although a signifi-

cant break point can

be noticed in the

curve.

The option Evaluate

induction time is deacti-

vated in the method.

Activate the evaluation of the induction time in

the method (see Chapter 4.5.2.2, page 64).

The option Evaluation

delay or Evaluation sup-

pression is defined in the

method, which prevents

the evaluation of the curve

in the corresponding time

period.

Deactivate the corresponding option in the

method (see Chapter 4.5.2.2, page 64).

Automatic detection of the

induction time is not yet

possible.

Keep the determination running until the

induction time is automatically found.

The curve progression is

too flat with the result that

automatic detection of the

induction time is not possi-

ble.

Do not use Endpoint(s) as a stop criterion in

the method, but instead a defined Conductiv-

ity e.g. 200 µS/cm (see Chapter 4.5.2.1, page

60). Evaluate the curves afterwards manually

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