The Ins and Outs of Calibration

alcoview_laptopWhen considering which breathalyzer is best for you, it is important to think about the maintenance of the device. ALL breathalyzers need to be calibrated – ie. They need to have the sensor set to recognize specific alcohol concentrations – to be able to give you an accurate reading. (that’s why the cheap £12 kits you can find on certain internet marketplaces are such a waste of money, as you CANNOT calibrate them – but that’s another blog post…)

Breathalyzer types fall into one of 2 categories – semi-conductor sensors (generally speaking, £100 or less, quoted accuracy between 10%-25%) and Fuel Cell Sensors (generally, £100+, quoted accuracy between 1.6%-5%).

The way they work is slightly different.   The semi-conductors are cheaper to manufacture because the sensor is only accurate at one or sometimes two alcohol concentrations, and then it uses software to generate a ‘reading’ if your alcohol level falls outside/within these calibrated points.

Fuel cells are more expensive to buy because they physically measure the volume of a sample, and use a linear method of measurement of the alcohol content within that sample – from zero 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 falling over (so to speak).

When we calibrate the breathalyzers, firstly we establish whether the device is working as expected by running it through calibration accuracy tests. The results from that then indicate what level of calibration is required.AlcoDigital Calibrators

In certain scenarios this is a ‘Wet Bath’ Calibration procedure. The calibrators are filled with specific certified alcohol concentrations, heated to 34’C and then connected to a pressurized flow meter attached to an air generator to provide an accurate 1.2 litres of air per sample. Once the calibration process has been performed, accuracy tests are taken at a range of calibration points, as well as a clear air ‘human’ sample – to ensure the device works to the manufacturer’s specifications. Only once we are 100% happy that everything is as it should be do we finally sign of the certificate confirming accuracy.
We also use a Dry Gas calibration system (which 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.

It is crucial for the life of your breathalyzer to make sure it is 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 and to book your unit in, see our website here or call us on 0208 454 7372.


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