Wika TR12-M Uživatelský manuál stáhnout pdf (Strana 26)

9. Calculation examples ... / 10. Maintenance and cleaning

11419904.02 09/2013 GB/D

WIKA operating instructions models TR12, TC12 (Ex d)26

Additional information:

Temperature class for T3 = 200 °C

Safety factor for type-tested instruments (for T6 to T3) *

= 5 K

Safety factor for type-tested instruments (for T1 to T2) *

= 10 K

Safety factor for applications for instrument category 1 (zone 0) *

= 80 % nds no

application here.

*1 EN 50014: 1997 section 23.4.6.1

*2 EN 1127-1: 1997 section 6.4.2

9.2 Example calculation for variant 2 with TC sensor

Under the same conditions it gives a lower value for the self-warming, since the supplied

power is not only converted at the sensor tip, but rather over the entire length of the

measuring insert.

Thermal resistance [Rth in K/W] from table = 3 K/W

Self-heating: 0.8 W x 3 K/W = 2.4 K

max

= T

+ self-heating: 150 °C + 2.4 °C = 152.4 °C

As safety margin for type-examined instruments (for T6 to T3), an additional 5 °C must be

subtracted from the 200 °C; hence 195 °C would be permissible. This means that in this

case temperature class T3 is not exceeded.

In this example it is clear that the self-heating here is almost negligible.

10. Maintenance and cleaning

10.1 Maintenance

The thermometers described here are maintenance-free.

Repairs must only be carried out by the manufacturer.

10.2 Cleaning

CAUTION!

■

Prior to cleaning, disconnect the electrical connections properly.

■

Clean the instrument with a moist cloth.

■

Electrical connections must not come into contact with moisture.

■

Wash or clean the dismounted instrument before returning it, in order to

protect persons and the environment from exposure to residual media.

■

Residual media in the dismounted instrument can result in a risk to persons,

the environment and equipment. Take sucient precautionary measures.

For information on returning the instrument see chapter 12.2 “Return”.

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