Danish knowledge centre DELTA now issues a warning that smoke measuring equipment used by manufacturing and type approval testing of smoke detectors may be inadequately calibrated.

Smoke detectors are important to fire detection and safety in buildings. Detection of the correct smoke density is, however, essential. Otherwise, trustworthy alarming is not possible.

The world standard for smoke measuring equipment is the MIC, which has been developed specifically for reference measurements of smoke density by Cerberus Ltd. of Switzerland. DELTA has been granted an exclusive license to manufacture and sell the equipment to customers worldwide. The MIC is based on the ionisation principle and is suitable for smoke measurements, e.g. in connection with testing of smoke detectors.

Approximately 400 MICs are used around the globe, and they should be calibrated every 1-2 years at DELTA's calibration facility. Only 10 MICs a year are returned to DELTA for calibration. This means that the vast majority of MICs do not fulfil the normal quality requirements.

It is difficult to point out to what extent this affects global fire safety.

It could of course have serious consequences if a smoke detector reacts too late. However, to connect such a failure to uncalibrated measuring equipment is not easy, but the MIC users are called upon to check the calibration status.

DELTA now contacts all known MIC users directly. In addition, a warning label will be placed on every new instrument leaving DELTA.