Comparison Alcoscan AL-8000 vs Alcoscan AL-7000

The type of sensor used in the instrument.

— Semiconductor. Sensor, which is based on a porous surface of a semiconductor material; when alcohol molecules enter the pores, the conductivity of the material changes, which is monitored by the device. This is the simplest and most inexpensive type of sensors, used mainly in low-cost category devices. Actually, the main advantage of this option is precisely the low cost; also from the advantages of semiconductor devices can be called compactness. On the other hand, they are inferior to electrochemical ones in terms of speed, accuracy and selectivity of measurements — the sensor material reacts not only to alcohol, but also to some other compounds (in particular, ammonia and ketone bodies), moreover, the result strongly depends on the ambient temperature. Such a sensor needs to be checked and calibrated quite often — about once every 2 to 4 months, depending on the intensity of use; and its service life is relatively short.

— Electrochemical. The action of this type of sensors is based on the reaction of alcohol with a special catalyst: during such a reaction, an electric current is generated, according to the intensity of which the device displays the measurement result. Electrochemical sensors are noticeably more expensive than semiconductor sensors, but have more advanced performance characteristics. So, they have a noticeably higher speed...of work; the catalyst reacts exclusively to alcohol, other impurities practically do not affect the measurement result; the accuracy of the device is almost independent of the ambient temperature; and verification and calibration of the sensor is required at most once a year, or even less often. Thus, most intermediate and professional level breathalyzers use this type of sensor.

— Thermocatalytic. Like the electrochemical sensors described above, such sensors have electrodes with a special catalyst deposited on them. The difference lies in the fact that the catalytic temperature sensor determines the alcohol level not by current, but by temperature change. Before measurement, the electrodes are heated by the passage of an electric current, and alcohol vapors enter into an oxidative reaction with the catalyst, due to which the temperature rises. This principle of operation provides good accuracy and selectivity, however, it requires quite a lot of energy, while in terms of performance, such sensors are still inferior to electrochemical ones. Because of this, thermal catalytic breathalyzers have not received much distribution.

The maximum measurement error provided by the device during operation, in other words, the largest deviation from the actual result that may occur during measurements. For example, if the error is claimed at the level of 0.1 ‰, and the measurement result is 0.5 ‰, then the actual amount of alcohol in the blood will be from 0.4 ‰ to 0.6 ‰.

In the most advanced models, this parameter is 0.05 ‰ or less ; values of 0.06 – 0.1 ‰ correspond to the average level, more than 0.1 ‰ — low accuracy. The lower the error, the more accurate the device, the more reliable its readings. On the other hand, high accuracy has a corresponding effect on the price. Therefore, when choosing according to this criterion, it is worth considering what exactly a breathalyzer is needed for and how important measurement accuracy is for it. In particular, for devices used by the traffic police, there are accuracy requirements that are expressly specified in regulatory documents.

The warm-up time of the breathalyzer to the working state, in other words, the time that must pass after switching on or after the end of the previous measurement before the device can be used.

The fastest modern breathalyzers warm up in 5 – 6 seconds, time up to 20 seconds is considered quite good; in slower models, this time can be up to a minute. At the same time, it makes sense to specifically look for a device with a short warm-up time only in cases where it is needed for streaming checks and high speed is crucial. And if the device is purchased for individual use with measurements a maximum of 2 – 3 times a day — you can not pay much attention to this parameter: waiting even a few tens of seconds is most often not a problem.

Built-in counter that records the number of measurements taken. The features of the operation of such a counter can be different — in particular, it can count from the beginning of the day, from the moment it was turned on, from the moment the sensor was last calibrated, etc. These details should be clarified separately. Anyway, the meaning of this function lies in the fact that most breathalyzers have restrictions on the number of measurements per day, and without automatic counting, it can be difficult to monitor compliance with these restrictions. In addition, the calibration and maintenance of the sensor also needs to be done after a certain number of measurements.

Type of power supplied by the device. The power supply methods used in modern breathalyzers can be divided into two types — replaceable cells of a standard size and original batteries.

The first option is convenient because dead batteries can be quickly replaced with fresh ones — the main thing is to have a supply on hand. At the same time, replaceable elements can be made both disposable and rechargeable, in the form of batteries. On the other hand, batteries usually have to be purchased separately — and either regularly buy more disposable cells, or spend a significant amount on batteries and a charger. Here are the main sizes of replaceable elements found in modern breathalyzers:

— AAA. Cylindrical-shaped batteries, known as "mini finger" or "little finger" batteries. A fairly popular option, especially among entry-level and mid-level breathalyzers: they are small in size, and although the capacity of such batteries is small, it is quite enough for the mentioned devices.

— AA. Classic, known to many "finger" batteries. For a number of reasons (in particular, due to the larger size), they are used in breathalyzers less frequently than the “little finger” AAA.

— PP3. Batteries of a characteristic rectangular shape with a pair of contacts on one of the ends. They are distinguished by a rather high voltage — 9 V. They are used mainly in professional devices with an abundance of additional functions that require a large amount of energy.<...br>
As for the original batteries, such batteries often outperform replacement batteries in terms of performance and do not require additional costs: the battery is purchased immediately with the device and in the future it is enough to periodically recharge it. On the other hand, charging requires time and a power source; it is usually impossible to quickly replace a dead battery. And the mentioned performance advantages are rarely decisive. As a result, this variant is relatively rare in breathalyzers.

The range of air temperatures at which the breathalyzer is able to work correctly. Note that if the device goes beyond this range, the device will not necessarily fail, but there is no need to talk about the accuracy of measurements in such a situation. This parameter is especially important for models with semiconductor sensors (see "Sensor") — the correct operation of such sensors is highly dependent on the ambient temperature. It is best to use such a device at a temperature corresponding to approximately the middle of the allowable range — in this case, the error will be minimal.

The most cold-resistant modern breathalyzers are capable of operating at sub-zero temperatures, the most resistant to heat — at temperatures of +45 ... +50 °C.