From the specialist archive: electrical practice Carbon monoxide - the invisible danger

Reliable protection in individual residential units offer battery -operated warning detectors that detect the toxic gas in low concentrations and warn residents.Warning detectors of the “Type A” are suitable for central heating systems, which can automatically switch off heating systems or switch on ventilation systems in the event of danger.

Especially in the heating season, the dangers are increasingly discussed in public by poisonous carbon monoxide.Carbon monoxide is odorless and is not perceived by the human sensory organs, but inhaling can lead to nerve damage and death after a short time.Particularly insidious is the widely unknown fact that carbon monoxide diffuse through walls and ceilings and a single defective gasher can endanger the residents of an entire apartment building in a short time.

In November 2014, for example, a carbon monoxide accident in the south of Hamburg's death and injured were to be complained about [1].After the measurement of high carbon monoxide values, the emergency services found three dead in various apartments of the two neighboring apartment buildings, which were apparently nipped on the highly toxic gas during sleep.13 residents were sometimes seriously injured.A defective heating system was identified as the cause, since the carbon monoxide concentration had normalized after it was switched off.Also three deaths and 30 slightly injured people were available in 2011 in a carbon monoxide accident in Wiesbaden [2].As the cause, a defective exhaust pipe of the central heating in the basement of the apartment building was suspected.In August 2018, the police and fire brigade had to evacuate a multi -party home in Uelzen.A carbon monoxide warmer had measured increased values and triggered early [3].In total, experts in Germany expect up to 370 deaths and 3,700 injuries annually by accidents with carbon monoxide [4].The number of cases is increasing: According to a report by the Ärztezeitung, the number of pressure chamber treatments at the University Hospital Düsseldorf UKD almost doubled in 2018 due to poisoning with carbon monoxide compared to the previous year [5].

Dangerous gas

Fire brigades and emergency services are increasingly equipped with mobile measuring devices, the carbon monoxide accidents are increasingly recognizable than in the past.However, if no carbon monoxide alarms are installed in the apartment, the rescue for crashed residents often comes too late, which is mainly due to the insidious properties of the poisonous gas.Even small amounts cause that the blood hardly transports oxygen and, as a result, breathing, confusion, vomiting and heart failure occur.Those who are saved often suffer from memory disorders, paralysis or dizziness months later.

In the case of incomplete combustion, carbon monoxide can occur in any fireplace with carbon -containing fuels.In the living environment, for example, gas, oil, briquette or pellet heating, fireplace or coal stoves as well as gas spots or gas boilers are.Further causes of the accident are due to bird nests clogged fireplaces or technical defects.But wood pellets can also release the toxic gas when stored.

High -tech in a confined space

Carbon monoxide alarms for private living areas reliably protect against the dangers of breathing poison.They raise the alarm even with low concentrations of the smell and tasteless gas and thus enable people present to bring themselves to safety.

The basic chemical reaction is easy, but only tricky measurement technology makes it usable.The picture shows the sensor structure of a real carbon monoxide alarm..The ambient air hikes through the gas diffusion opening to the work electrode, which protects an activated carbon filter from unwanted gases such as hydrogen or alcohols.In order to increase the sensitivity of the sensor through a large surface, the platinum of the electrodes on porous Teflon (PTFE) is evaporated.Sulfuric acid is used as an electrolyte in a gel, which also binds the water created on the counter electrode.

When measuring the carbon monoxide, only an extremely low electrical current flows.For example, with a carbon monoxide concentration of 100 ppm, it is only 4 mA.The electronics for reinforcement and noise suppression as well as compensation for long -term deviations (drift) are correspondingly elaborate.For better conductivity, the external contacts of the sensor are gold -plated and the inner wire connections made of platinum are made.The actual alley is relatively small, while most of the housing of electronics, display and the alarm tone is used.

The heart, the electrochemical sensor, should be calibrated in real gas and trigger a pre -alarm from about 40 ppm.

It is extremely useful that specialist installers and repairers can read the detectors through a smartphone app such as audio links.In this way, it can also be determined afterwards whether a co-event has taken place between the test intervals of the heating system, for example, which in its actual concentration did not lead to triggering the warning detector.If that was the case, possible sources of danger can be identified and eliminated.

Expertise required

The European application standard DIN EN 50292 [6] contains detailed information on the installation and maintenance of carbon monoxide alarms.Also in the new edition of the application standard for smoke alarms DIN 14676-1 [7] that has been valid since December 2018, it is recommended to install carbon monoxide alarms in rooms with combustion equipment.

However, since the use of carbon monoxide alarms in Germany is not regulated by law, the specialist knowledge of the installers is particularly important when planning and assembly.You are required to acquire the necessary knowledge of the danger situation and suitable prevention measures yourself.One possibility is the training for the "TÜV-checked specialist for carbon monoxide in living rooms and leisure vehicles"

Author: p.kennedy

Literature:

[1] Hamburg;Germany: Carbon monoxide poisoning: The cause of gastras in Hamburg Further unclear - Spiegel Online - Panorama, 2014.

[2] Three dead and over 30 injured in carbon monoxide accident in apartment building, 2011, Wiesbaden112.de.

[3] Carbon monoxide alarm in multi-party house in Uelzen, 2018, AZ-Online.

[4] Kaiser, G.;Schaper, A.: Acute carbon monoxide poisoning;Emergency + rescue medicine 15 (2012), Issue 5, S.429–435.

[5] UKD: Poisoning with carbon monoxide is increasing, 2018, Ärztezeitung.

[6] DIN EN 50292: 2014-08 Electrical devices for the detection of carbon monoxide in houses, caravans and boats-guidelines for selection, installation, use and maintenance.

[7] DIN 14676-1: 2018-12 smoke alarms for houses, apartments and rooms with apartment-like use-part 1: Planning, installation, operation and maintenance.

The full article can be read in our specialist archive.