Operation / Maintenance - TESTO 6440 Instruction Manual

Operation / Maintenance

Dysfunction displays
Meas. value > 120% of meas. range scale value cf. page 21.
Meas. value < starting value of meas. range cf. page 21.
Flashing: Short circuit in switch output 1.*
Flashing: Short circuit in switch output 2.*
Flashing: Short circuit in both switch outputs.*
Flashing: Malfunction of measurement probe.
*The affected output is switched off, as long as the short circuit carries on.
These warnings are shown even when the display is switched off.
The instrument is maintenance-free in media that do not adhere to
the measurement probes.
• As necessary, check the measurement probes optically for depo-
sits.
• If necessary, clean them at certain intervals. Use a suitable clea-
ning liquid (e.g. alcohol solution).
• Avoid mechanical damage to the measurement probes.
Flawless operation and adherence to measurement accuracy can
only be guaranteed if the ambient conditions stated in the "Technical
Data" on page are complied with. Pay special attention that the
maximum pressure range, the measuring range, the humidity range
and the acceptable ambient temperature are not exceeded.
To monitor compressed air humidity, we recommend the pressure
dewpoint measurement transmitter testo 6740.
• Excessively high humidity leads to lower accuracy, not to
damage.
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