WIKA T32.xS - Manual (Page 15)

GB
15 WIKA safety manual temperature transmitter T32.xS
11583631.02 11/2010 GB/D/F/E
WARNING!
After the proof test of the device, start a functional check of the entire
safety function (safety loop) in order to test whether the transmitter
ensures the safety function of the system. Function tests are intended
to demonstrate the correct function of the whole safety-related system,
including all instruments (sensor, logic unit, and actuator).
2.9 Information on the determination of safety-relevant parameters
The failure rates of the electronics were determined using FMEDA in accordance
with IEC 61508. The calculations were based upon the component failure rates in
accordance with SN 29500.
The following assumptions have been made:
■ The transmitter are only operated in low demand mode applications.
■ The mean ambient temperature during the period of operation is 40 °C.
■ The MTTF following a device failure is 8 hours.
In accordance with ISO 13849-1 a maximum service life for the transmitter of 20 years
is assumed. Replace the device after this time.
2.10 Decommissioning the transmitter
WARNING!
Ensure dvices that have been taken out of service are not accidentally
recommissioned (e.g. through marking the instrument). After
decommissioning the temperature transmitter, a functional test of the
entire safety function (safety loop) should be initiated, in order to test
whether the safety function of the system is still ensured. Function tests
are intended to demonstrate the correct function of the whole safety-
related system, including all instruments (sensor, logic unit, and actuator).
2. Safety