What you learn today
- RatioOxygen and RatioCarbonDioxide
- Calculate partial pressure
- Limits for breathing air
21 % oxygen sounds like good air. In a room at 30 kPa it is still too little. What counts for the lungs is not the share but the partial pressure: how much of the total pressure falls on the oxygen.
Reading shares
A gas sensor returns a share from 0 to 1 for every gas:
| LogicType | Gas |
|---|---|
RatioOxygen | oxygen |
RatioCarbonDioxide | carbon dioxide |
RatioNitrogen | nitrogen |
RatioPollutant | pollutant |
RatioMethane | methane (also called “volatiles” in the game) |
Computing partial pressure
Partial pressure = total pressure × share:
lbn press SENSOR HASH("Wohnen") Pressure Average
lbn share SENSOR HASH("Wohnen") RatioOxygen Average
mul po2 press share # oxygen partial pressure in kPaAt 101.3 kPa and 21 % that is a good 21 kPa. At 50 kPa and 21 % only 10.5 kPa.
The limits
| Value | Limit | Meaning |
|---|---|---|
| oxygen partial pressure | from 16 kPa | full breathing; below you breathe worse, without oxygen damage starts after a few seconds |
| pollutant partial pressure | from 0.5 kPa | warning; from 1 kPa the lungs take damage |
| total pressure | from 607.95 kPa | breathing gets strenuous |
| temperature | below −10 °C or above 50 °C | the lungs suffer |
In the game, pollutant, methane, hydrazine, silanol and hydrochloric acid gas are toxic.
And CO₂?
Carbon dioxide is not a poison in the game. Still, RatioCarbonDioxide is worth watching: in a closed room people turn oxygen into CO₂. If the CO₂ share rises, someone is using up oxygen and filters or plants cannot keep up. A CO₂ limit is therefore an early warning you set yourself.
Adding more CO₂ does not push the oxygen out – the pressure simply rises. Whoever only looks at the oxygen share sees it drop and thinks the air is worse than it is. The partial pressure stays the same. So: always compute the partial pressure.
For a percentage display you do not need to compute: write the share directly to a display in Percent mode.
Exercise
Task
A breathing air guard for the living area. On the network: gas sensor “Wohnen”, LED display “O2-Teildruck”, flashing light “Atemluft”.
- The display shows the oxygen partial pressure in kPa.
- The flashing light warns when the oxygen partial pressure is below 16 kPa, the pollutant partial pressure reaches 0.5 kPa or more, or the sensor is missing.
Hints
Hint 1
Partial pressure: read the share, multiply by the pressure.
Hint 2
Warning: slt for oxygen, sge for pollutant, joined with or.
Hint 3
Sensor gone: snan on the pressure and one more or.
Quiz
4 questions. You pass from 60 % – the server does the grading.
Complete the day
- Passed the simulator exercise
- Passed the quiz with at least 60 %
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