How Frequently Do You Need to Replace Breathalyser Sensors?

Today’s digital breathalysers are calibrated at the factory to guarantee that the sensors provide accurate readings. Eventually, alcohol and other pollutants in the environment affect the settings and ultimately reduce the accuracy of the readings.

Breathalysers that have sensors that are fixed need to be returned to a service centre to get re-calibrated. Breathalysers that have sensors that are replaceable, like the AL6000 breathalyser, are automatically reset to the original factory settings when the sensor module is replaced.

How does a Breathalyser Work?

In order to understand why it is important to regularly change the sensor in your breathalyser, it is worth knowing how a breathalyser works.

As soon as you have a drink, alcohol is digested and begins to enter the bloodstream via the stomach wall. In general terms, neat alcohol drunk on an empty stomach will enter the bloodstream quicker than a less potent drink (for example, a milk based cocktail) drunk on a full stomach. This does not mean that drinking a neat spirit will make you drunker, it just means that effect is probably going to be felt much quicker.

Once alcohol is in your blood it moves around your body, producing all the usual physical brain and body effects that you feel when you have had a drink. The liver’s job at this stage is to slowly filter the alcohol out of your bloodstream. With each “pass” more alcohol is filtered out until eventually no alcohol remains in the body.

As well as the liver, alcohol also enters the lungs. When you breathe, some of the alcohol in your blood moves into the air in your lungs. This alcohol in deep lung air is what is measured when you take a breathalyser test.

Whenever a breathalyser test is to be taken, it is important that the person being tested has not drunk with the last quarter of an hour. If they have, any alcohol left in their mouth would be blown into the breathalyser. This alcohol will be at a higher concentration than that in blood and would give a false reading.

As you can see from this explanation, a breathalyser works on detecting alcohol concentrations that are very low. This is why uses should not smoke or drink prior to taking a breathalyser test. This is also the reason why the breathalyser sensor should be changed on a regular basis, in order to ensure a correct blood alcohol result.

For what length of time will the breathalyser sensing unit retain its accuracy and reliability?

When the sensor is used normally, around 250-300 tests, it will retain its accuracy for a minimum of 12 months.

The sensor will lose its accuracy depending on the following factors:

  • Subjection to intense temperature (glove box in hot months)
  • Exposure to severe cold (glove box in winter time)
  • Contact with excessive amounts of alcohol in breathing samples
  • Not ventilating the sensor following use with moisture build-up (oxidation)
  • Subjection to tar in samples of those who smoke

If it is vital to have readings that are accurate, replace the sensor after around 200 tests or 6 months.

What tests can I perform to ensure that the breathalyser sensor is providing accurate readings?

Not sure of the age of your sensor or if it was stored properly? Do a series of 3 tests with a positive breath sample within a 5 minute time period. If a good sampling technique varies by more than +/- 10%, it is time for the sensor to be changed.

Replacement AL6000 Sensor

We can now offer a replacement sensor for our popular AL6000 Breathalyser. These sensors are calibrated in mg/l. Te replace an existing unit, please ensure that you have a unit with a RED circuit board and a BLUE coloured circle on the sensor. Breathalyser units that have a GREEN circuit board, or a coloured circle that is not blue, cannot be replaced with our sensor.

Replacement AL7000 Sensor

If you are lloking to replace the sensor in anAL7000 breathalyser, we can also help. The AL7000 uses a unique sensor called PRISM (Pre-calibrated Replaceable Intelligent Sensor Module) that can be changed by the user. We recommend that this be done every 6 months, or every 200 tests to ensure accurate operation of the breathalyser.


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