... Tests Certificates of Conformance, Calibration Certificates, NPL, NAMAS: the plethora of certificates and approvals available to users of instruments is enough to fog the clearest of minds. So what do they all mean? How can users be sure that their instruments are accurate? Is the law on their side...

...Peter McGeehin Highlights lessons which can be learned about residential carbon monoxide detectors. States that four types of sensor technology can be applied and points out the drawbacks of three of these. Describes the fourth technology, used in SEMDEC sensors, and discusses tests carried out...