What is a breathalyzer calibration and how does it work?

How does a breathalyzer calibration work?

First you need to understand the breathalyzer in a bit more detail:

All breathalyzers require a level of maintenance, these involve costs and should be considered when searching for the best breathalyzer for you. ALL breathalyzers need to be calibrated. This is done by setting the breathalyzer sensor to recognize specific alcohol concentrations – to be able to give you an accurate reading. Kits that can not be calibrated are a waste of money as they can not be accurate.

There are two breathalyzer types: semi-conductor sensors (usually £100 or less, quoted accuracy between 10%-25%), and Fuel Cell Sensors (generally, £100+, quoted accuracy between 1.6%-5%).

Semi-conductors are cheaper to manufacture because the sensor is only accurate at one or two alcohol concentrations. It then uses software to generate a ‘reading’ if your alcohol level falls outside or within these calibrated points.

Fuel cells are more expensive to buy because they measure a volume of sample. They then use a linear method of measurement of the alcohol content within that breath/air sample. This measures from zero (alcohol) through to about 10 times the current English limit – to give accurate and consistent results time and again. They are also able to withstand extremes of heat and alcohol without it affecting the long-term accuracy.

What happens when we receive a breathalyzer in for calibration?

First we run a calibration accuracy check, which establishes whether the device is working as expected from the manufacturers specification. The results from this indicate what level of calibration is required.

Depending on the breathalyzer it will require either a ‘wet bath’ or ‘dry gas’ calibration (you don’t need to know which one it requires when sending it into us for calibration, just whether it is a semi-conductor or a fuel cell).

‘Wet Bath’ Calibration – The calibrators are filled with specific certified alcohol concentrations which are heated to 34’C. This is connected to a pressurized flow meter attached to an air generator to provide an accurate 1.2 litres of air per sample. The breathalyzer is told to recognize the sample at the level of alcohol within it.

Dry Gas Calibration – This is utilized alongside the Draeger Diagnostics Service software which enables us to process the calibrations on our Fuel Cells, check software updates, clear data errors and generally make sure everything is working as it should.

Post Calibration

Once the calibration process has been performed, accuracy tests are taken at a range of calibration points and a clear air ‘human’ sample. Only once we are 100% happy that the breathalyzer is working to the manufacturers specification we finally sign of the certificate confirming accuracy.

Your breathalyzer needs to be serviced on a regular basis. In the same way your car should be put through a service & MOT on an annual basis, personal breathalyzers should also be checked every 12 months.
With the professional equipment, part of the Home Office Approval dictates they are checked every 182 days (6 months) – to ensure a positive test result is legally defensible.

We offer a range of calibration services – from the standard semi-conductor service through to a full Courier Collect & Return service. For more details see our website here.