The BGS-04 type devices are used to detect different gases and vapours. By using them, fast and accurate values are available.
The sensor heads used in the device have a unified interface and similar electronic parameters, so simply changing the gas-sensor heads can fulfil different requirements.
Two types can be distinguished by considering operation:

• By electronabsorbtive and
• by amperometric principle.

The electronabsorbtive sensors have a wide range of measure, a minimal need of maintenance and a low price, their precision is typically 5-10 %. The amperometric heads have a narrower measuring range and a higher price, their average duration is 12-24 months, but their precision is typically 0.1 %. The electronabsorbtive sensors have a resistant output, and the amperometric sensors have current output, as follows:

R ~ k*R*T*ln(c)
I ~ k*R*T*ln(c)

A maximal four gas-sensor head can be placed into each BGS-04 type device; their signals (resistant or current output) are amplified, normalised and digitalised by the BGS-04 sensor. As a fifth channel, every BGS-04 device measures it's head's temperature, so temperature-independent, accurate measures can be performed.