Vega MINITRAC 31 4 … 20 mA_HART - four-wire With SIL qu Bedienungsanleitung PDF herunterladen (Seite 9)

3 Product description

MINITRAC 31 • 4 … 20 mA/HART - four-wire

43389-EN-131119

on the density of the measured media. The measuring principle has

proven to be very reliable in conjunction with extreme process condi-

tions because it measures contactlessly from outside through the ves-

sel wall. The measuring system ensures maximum safety, reliability

and plant availability independent of the medium and its properties.

3.3 System limitations

Thereareseveralmeasuringprinciple-specicfactorswhichcaninu-

ence the measuring result. Keep these factors in mind in order to fully

utilize the capabilities of the instrument with respect to measurement

certainty and reproducibility.

The implemented radioactive isotope and its activity must be selected

according to the properties of the vessel and the medium. The neces-

sary radioactive activity must be calculated on the basis of the plant

data.

To this end, make use of our planning service for an optimum layout of

the measurement and selection of the isotope. This applies particu-

larly to SIL applications.

Due to the physical properties of the radioactive radiation, the pulse

rateissubjecttoslightuctuations.Setasuitabledampingleveltoget

a stable measured value.

The relation between level and the pulse rate measured by the sensor

is not linear.

Set up a linearization table to get a linear level signal. For precise

mesurement results, make sure when setting up the linearization

tablethattheactualllingheightofthemeasuringpointsisenteredas

exactly as possible.

Externalradiationsourcescaninuencethemeasuredvalue(e.g.

welding joint tests). In safety-relevant applications, the safety function

must be treated as unreliable as long as the external radiation occurs.

If necessary, you must take measures to maintain the safety function.

Make sure during the planning that for the planned application, a

possiblylargedierentofthepulseratewithemptyandfullvesselis

reaced. This applies mainly for products with low density or in vessels

with extremely small diameter.

3.4 Packaging, transport and storage

Your instrument was protected by packaging during transport. Its

capacity to handle normal loads during transport is assured by a test

based on ISO 4180.

The packaging of standard instruments consists of environment-

friendly, recyclable cardboard. For special versions, PE foam or PE

foil is also used. Dispose of the packaging material via specialised

recycling companies.

Activity of the source

Non-linearity of the pro-

cess value

External radiation

Span

Packaging

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