Digital Thermometer

Details

A plain digital clinical thermometer with a flexible tip and a fully sealed body. An accuracy figure with no range attached is not a specification. Almost every thermometer on the shelf prints plus or minus 0.1 degrees and stops there, and a sensor that holds a tenth of a degree at 37 does not hold it at 34 or at 42.5. So the figure here is given in bands, and the band that matters, the fever range, is stated first. The second thing worth knowing is what the ten second reading actually is. It is predictive: the thermometer watches the early rise curve and extrapolates where the temperature will settle. That is a legitimate and normal design and it is not a direct measurement. Hold it for a full 60 seconds and you get a direct reading instead. In our bench data the two agree within 0.1 degrees, and where they differ the 60 second figure is the one to trust. The third is that on a person the instrument is rarely the largest error. Site is. Under the arm reads roughly 0.3 to 0.5 degrees below the mouth, and the mouth roughly 0.5 below rectal. Compare a reading to yesterday's reading from the same site, not to a number from a different one.

• Accuracy plus or minus 0.1 degrees Celsius from 35.5 to 42.0, and plus or minus 0.2 from 32.0 to 35.4 and from 42.1 to 43.0
• Resolution 0.1 degrees. Measuring range 32.0 to 43.0 degrees Celsius, switchable to Fahrenheit
• Calibrated against a NABL-traceable reference in a stirred water bath at 37.0 and 40.0 degrees, unit by unit, with the certificate on this page
• About 10 seconds to the beep, which is a predictive reading. 60 seconds gives a direct one
• Flexible tip, which matters when the person holding still is two years old, and a body sealed to IP27 so it can be washed rather than wiped between people
• Mercury free. A drop on the floor is a nuisance, not a hazard and not a clean-up
• One LR41 coin cell, user replaceable, about 200 hours of use. Nothing is sealed in and nothing is glued
• It measures body temperature. It does not diagnose anything, and a number on its own is not a reason to start or stop a medicine
• The laboratory accuracy figure is a water bath figure. On an arm or under a tongue the technique and the site move the reading further than the instrument does