Air – breath of life, raw material, tool

No second without air

The Bergmann family is made up of father Wolfgang, mother Vera and their fifteen-year-old daughter Amelie and twelve-year-old son Jonas. The family lives in a single-family house in the green belt of a major city. Wolfgang Bergmann is an engineer while his wife works as a doctor in the radiation oncology department of the regional hospital. Like the average European, the family spends nearly 90 percent of time in closed rooms.

6.00 am: The day begins

Once Vera has dragged herself out of bed, she first goes to the window in the bedroom and opens it wide. She breathes in the fresh, cool morning air. This does a lot of good but is also necessary, since a lot of oxygen is consumed when sleeping at night. With every exhalation, the oxygen in the air is reduced to approximately 17 percent, while at the same time, around 4 percent CO₂ (carbon dioxide) is produced. In closed rooms, the CO₂ content therefore rises very quickly, and reduces the quality of the indoor air.

7:15 am: On the subway

While the children are still sitting and eating their breakfast, Vera Bergmann is already on her way to work. She uses the escalator to get to the lowest subway platform. The fact that passengers have enough air to breathe underground is thanks to technology: The station is ventilated by central ventilation systems, meaning primary filtration is at work. Outside air is treated and repeatedly extracted by simple ventilation.

The air flow is also important in other traffic tunnels. The size of the volume flow of air depends on the size of the load using the tunnel. In a car tunnel, this means the traffic flow, i.e. the number of vehicles, as well as their CO₂ emissions. For example, for a 3-kilometer-long tunnel and a traffic flow of 2,000 cars per hour in each direction, the required outside air volume is 3 040 000 m³ per hour or 844 m³ per second. This corresponds to approx. 280 m³ per second for each kilometer – a considerable flow of air, whose weight per hour is approx. 4 tons.

7:50 am: At school

The new building of the secondary school that Jonas and Amelie attend is only a couple of blocks from the biogas plant. Inaugurated only three months ago, the building was constructed according to the latest technical standards and contains state-of-the-art heating, air conditioning and fire protection technology.

In order to be able to listen, understand and learn well, our brain needs good air. Numerous studies demonstrate the correlation between the quality of the air and people’s ability to concentrate. Particularly in regions with sub-optimal outside air quality, technical ventilation with high-quality supply air filters is preferable to window ventilation. In modern low-energy buildings, as in the Bergmann children’s school, technical ventilation is indispensable for ensuring a high quality of the air inside.

8:30 am: In the furniture factory

Wolfgang Bergmann’s workplace is close to the children’s school. He works as an engineer in a furniture factory, where he is responsible for the wood processing.

In the entire building where Wolfgang works, an optimized air exchange takes place. This not only ensures the right room temperature and a low CO₂ content, but also optimal air humidity. Furthermore, the incoming air is cleaned of airborne particles, pollen and other harmful components. All necessary measures are taken to ensure high air quality in the workplace. In return, the factory has high-performance filter systems that allow only purified air to escape into the open air.

9:50 am: In class

The bell rings to signal that break is over and the physics class is about to begin. But, a surprise awaits the children: The physics teacher has brought chocolate-covered marshmallows for all. Why? Today, Amelie and her classmates are learning about vacuums, including how they are generated. They will also learn of the effects of the absence of air on a chocolate marshmallow.

For this, the physics teacher attaches a vacuum pump to a bell jar. After opening the valve between the vacuum pump and the jar, the air is extracted from the jar so a vacuum is generated. As a result, the bubbles in the chocolate marshmallow expand and enlarge their volume many times over. When the air then flows back into the bell jar, the pressure which has an effect on the white foamy mass of candy is once again raised to the normal value. Thus, the chocolate marshmallow is returned to its original size, though is now somewhat dented.

11:00 am: In the hospital

While Amelie is learning about vacuums in school and nibbling away at chocolate, Vera Bergmann treats her tumor patients. She knows that air or the exact opposite, namely a vacuum, can be life-saving – as in the radiotherapy of malignant tumors.

An impressive example of modern vacuum applications is the particle or ion beam therapy of malignant tumors, for example in the head and neck area. In this process, protons or carbon ions are accelerated to a very high speed and then directed exactly to the tumor tissue. The particles damage the malignant cells irreparably. With this highly precise technique, tumors can be treated in a more targeted way than with older methods – without harming healthy tissue. The vacuum acts as a valuable tool, since all steps from the source to the radiation target are performed in a vacuum. As a result, the beam can be accelerated to high speeds, unlike natural air, and reaches the diseased parts of the body without any loss.

11:30 am: At the airport

Wolfgang Bergmann has to take a plane to get to his business meeting – and he is also thinking about vacuums, albeit unconsciously: While waiting to board, he watches the airplanes that are chartering onto the runways. He looks at the big turbines and wonders how such a vital component of the aircraft is made with all its subcomponents.

Indeed, the requirements on the material of aircraft turbines are very high. The steels or alloys used must be hardened and/or refined. The heat treatment required in this process is carried out in a vacuum. In this way, for example, dissolved or unwanted trace elements are removed from metallic melts. Depending on the system or application, vacuum pumps with various operating principles are used.

While waiting, Wolfgang contemplates about security. What would happen if a fire broke out in the airport building? In this case, preparations are in place: An intelligent technology ensures that in the event of a fire, the smoke is led out of the building through mechanical smoke extraction systems in specially designed chimneys.

3:00 pm: On the school bus

While their parents are still at work, Jonas and Amelie have already finished at school and travel home together on the bus. When the doors open and close, they make a short “pfffff” sound – because here, too, air is at work: Compressed air.

Compressed air is simply air compressed beyond the atmospheric pressure. This pressure is achieved by compressors. Unlike in the case of liquids, compression always produces heat – this is noticeable when getting on and off.

4:00 pm: In the children’s room

Once the children have arrived at home, Jonas prefers to complete his homework straightaway. While he is tackling his numeracy, he eats a few biscuits and – oops – he has made crumbs on the floor. Jonas quickly grabs the vacuum cleaner to remove the crumbs. Without knowing it, Jonas is now performing exactly the same procedure that takes place in the factory where his father works during the extraction of the wood dust. However, in the factory, this takes place before the shavings and the wood dust reach the floor. The filter in the vacuum cleaner and in the large filter systems work according to the same principle. In both cases, the dust is disposed or recycled afterwards.

5:00 pm: In the supermarket

After finishing her work in the hospital, Vera goes to buy groceries at the supermarket. The quality of food is quite important for her – and here, too, compressed air is vital. For example, compressed air, whose purity is also precisely defined, is necessary for the transportation of flour from the mill to the packaging.

9:00 pm: On approach

Wolfgang Bergmann is on his way back after a successful business meeting. During landing, he notices that only very few headlights are installed for the illumination of the runway at night. This is thanks to the high performance of the modern headlights. To enhance the intensity of the light, they have special reflectors which have been manufactured using vacuum technology.

10:15 pm: Time to relax

Finally, a long day at work is over and the children are lying in bed. Vera and Wolfgang sit together on their sofa in the living room. They sit back to relax and enjoy a cool beer, which has of course been brewed according to the German purity law – and thanks to compressed air.

Without compressed air, there would be no beer to quench thirst. Breweries use compressed air almost everywhere. For example, for the valve controls in almost all departments, to clean the huge tanks or to ventilate the beer wort.