ECOTEST DKG-21 Operating Manual page 15

3.2.28 The dosimeter constantly monitors and displays the storage
battery discharge level on the dLCD. It is displayed with the help of the
battery symbol.
3.2.29 The dosimeter ensures self-testing of the dLCD and the
loudspeaker, which is done when the dosimeter is switched on.
3.2.30 The dosimeter records and displays on the dLCD a sign of DER
outranging the upper limit of the measurement range during the device
operation.
3.2.31 Design of the dosimeter provides for its deactivation.
3.2.32 Reliability requirements
3.2.32.1 Mean time to failure, not less than 6000 h. Failure criterion is
nonconformity to the requirements stated in 3.2.2.
3.2.32.2 Average value of operational readiness, not less than 0.999.
3.2.32.3 Mean time to repair, not less than 10000 h, and average service
life (with the storage battery replacement) - not less than 10 years.
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