Air Quality, Air Quality sensor, VOC sensor, Mixed Gas sensor for schools, authorities and companies

1-Wire Multisensors, Air Quality Sensor or VOC Sensor

An Air Quality sensor or VOC sensor is a gas sensor for measuring pollutants in the ambient air. These sensors are used in very different areas, e.g. for monitoring the air inside motor vehicles or increasingly also in buildings. Depending on the task, the Air Quality sensor can be either free-standing in buildings or mounted within piping systems of ventilation systems.

Functional principle of the Air Quality sensor

The functional principle of the Air Quality sensor (metal oxide semiconductor) is based on the fact that an electrically conductive resistor (sensing element) can change its conductivity under the influence of different air components. From this change in electrical resistance, the presence and indirectly the concentration of a pollutant can be inferred.

To operate the Air Quality sensor, the sensing element is heated to a fairly high operating temperature of approximately 250°C. In order for the sensing element to react well with the ambient air, a warm-up period is necessary to "burn off" oxidation layers.

An electrical circuit can convert the change in resistance of the sensing element into an output signal corresponding to the gas concentration.

The 1-Wire Multisensors or Air Quality sensors offered by ESERA respond to odorous substances, such as ammonia and H2S, generated from waste materials in offices and homes.

The Air Quality sensor also reacts with high sensitivity to low concentrations of VOCs (volatile organic compounds) such as toluene, which are used in wood finishing or various building products..

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1-Wire Multisensor Air Quality Humidity and Temperature Sensor Pro II

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Product number: 11152

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Details

Sensor function Air Quality sensor

The 1-Wire Multisensors or 1-Wire Air Quality sensors detect the air quality of a living space and thus provide useful information as to whether ventilation is necessary or whether a ventilation system should increase the ventilation level.

Especially in the autumn and winter months, we humans tend to ventilate our living spaces too little or too short. Not to mention the night hours, when we use up oxygen but cannot open a window. This is where our 1-Wire Air Quality / Multisensors come in handy and provide information about the air in our homes.

Often these 1-Wire Multisensors / 1-Wire Air Quality sensors are also called "fug sensors", because they do not only detect CO2, but a wide range of substances in our indoor air. This type of air quality measurement is not about a highly accurate measurement, but rather about outputting values for "good", "sufficient" or "ventilation", comparable to a traffic light.

The 1-Wire Multisensor 11151 has these "air quality traffic lights" in the form of LED displays in green, yellow and red. This means that the air quality is directly signalled visually.

All 1-Wire Multisensors / 1-Wire Air Quality sensors output a measured value of the air quality.

Via the 1-Wire Controller / 1-Wire Gateway devices, the measured values are output directly based on (equivalent) the values of CO2 sensors.

The 1-Wire Multisensors Pro Art. No. 11151 and 11152 include a temperature sensor, relative Humidity sensor and Air Quality sensor. The 1-Wire Air Quality Sensor Pro 11161 is a pure Air Quality sensor.

The 1-Wire Multisensors / 1-Wire Air Quality sensors are the optimal living space sensors for controlling a heating or ventilation system. The 1-Wire Multisensors can be used for all types of room air monitoring in commercial and educational areas. Even a demand-oriented fan control in toilets and sanitary areas is possible.

Besides CO2, body vapours such as alcohol, sweat, ammonia and various solvents are also detected.

Stand-Alone operation Air Quality sensor with Air Quality traffic light

The ESERA Air Quality living space sensor can also be operated without connection to a 1-Wire Bus system thanks to the integrated air quality traffic light. Only a power supply with 5V DC voltage is required. Due to the internal sensor controller, stand-alone operation is possible at any time. The ambient air is also analysed and a qualified statement about the air quality traffic light is output. Thus, every room can be monitored, with or without connection to a home automation system..

Mounting the Multisensor and Air Quality Sensor

The 1-Wire Multisensors / 1-Wire Air Quality Sensors may only be used in dry indoor rooms. The sensors are intended for mounting as stationary devices indoors.

During operation, 1-Wire Multisensors / 1-Wire Air Quality Sensors heat up slightly, therefore sufficient ventilation of the sensor must be ensured. Otherwise, deviating measured values may occur. The sensor must be mounted upright, with the ventilation openings at the top and bottom.

When mounting the 1-Wire Multisensor 11151, please make sure that the sensor is not shaded, otherwise the LED's could be permanently off due to night shut-off.

Commissioning of Multisensors with Air Quality

For the Air Quality Sensors integrated in the 1-Wire Multisensors / 1-Wire Air Quality Sensors it is normal that they require a "warm-up time" after connection of the supply voltage. The warm-up time differs between the various 1-Wire Multisensors.

Current consumption Multisensor with Air Quality

1-Wire Multisensors / 1-Wire Air Quality Sensors also differ in terms of current consumption. The 1-Wire Multisensor Pro I (11151) and the 1-Wire Air Quality Sensor Pro have a system-dependent current consumption of approx. 45mA at 5V operating voltage.

Due to a different, higher quality air quality measuring element, the current consumption of the 1-Wire Multisensor 11152 is considerably lower, at approx. 22mA (5V)

Recalibration (referencing) Multisensor with Air Quality

The sensor elements are subject to a certain aging, which may require a new calibration. A simple and very good method is to expose the sensor to fresh air for some time and perform the "Calibration" function. This will calibrate the sensor output value of approx. 400-450 ppm. The value 400-450 ppm corresponds to the CO2 concentration in rural and urban areas. The value may be slightly higher in urban areas. Please note that you can falsify the calibration already by your presence and exhalation. Keep a distance of several meters during calibration.

Power supply

During planning and commissioning, care must be taken to ensure that the power supply and the cabling can permanently deliver sufficient power. When using CAT network cables for installation, several cores must be provided as ground cables and at least 2 cores as 5V. Due to the heating of the AirQuality measurement Sensor, a significantly higher current consumption of approx. 22 to 45mA at 5V can be assumed compared to other 1-Wire Multisensors. For power supply we recommend to use one of our 1-Wire Hub devices.

Features of ESERA Multisensors or Air Quality Sensors

11151 1-Wire Multisensor and 11161 Air Quality Sensor

During commissioning, the integrated sensor controller checks with which warm-up stage (time) the sensor starts. The three possible stages of the warm-up phases are indicated by the three LEDs on the front.

Level 3, red LED: In new condition or after along operating pause

In new condition or after a long operating pause, the sensor starts with a warm-up time of approx. 15 hours. During this time the red LED flashes and 0% air quality is constantly output via the 1-Wire interface.

Lewel 2, yellow LED: power interruption of several hours

After a power interruption of several hours or days, the sensor starts with a warm-up time of approx. 2 hours. During this time the yellow LED flashes and 0% of the max. air quality value is constantly output via the 1-Wire interface (DS2438, Current Sens).

Lewel 1, green LED: short power interruption

After short power interruptions the sensor starts directly into normal operation.

The sensor automatically switches to normal operation after the warm-up phase is complete.

A light sensor is installed in the area of the upper ventilation opening, which automatically switches off the LEDs in the dark. The sensor function is not affected by this. The brightness sensor cannot be read out.

11152 1-Wire Multisensor

The "warm-up time" is about 7 minutes.