Properties of Gases and Vapours
Gases are substances with boiling points below 20°C at normal pressure, like hydrogen (H₂) and tungsten hexafluoride (WF₆). Gases follow the ideal gas law, where volume, pressure, and temperature are interrelated.
Vapours refer to the gaseous state of substances below their boiling point, existing in equilibrium with their liquid or solid phase. Vapour concentration is dependent on temperature and can be described by the vapour pressure curve.
Atmospheric Composition
The Earth’s atmosphere consists mainly of nitrogen (N₂), oxygen (O₂), and trace amounts of other gases. The composition changes slightly with humidity.
Gas Hazards
Gases pose three primary risks:
Explosion (Ex) from flammable gases.
Oxygen (Ox) risk due to oxygen deficiency or excess, which affects breathing and flammability.
Toxicity (Tox) from toxic gases.
The concentration of gases like hydrogen sulphide can be dangerous, as high concentrations may not be detectable by smell, posing a significant hazard.
Detection Technologies
Portable Gas Detectors: Devices like the Dräger X-am series, used for detecting gas concentrations in various environments.
Stationary Gas Detectors: Installed systems for continuous monitoring in fixed locations.
Dräger-Tubes: A manual method for detecting specific gas concentrations using colorimetric tubes.
Measurement Methods
Gas concentration measurements are essential for explosion protection and ensuring safe environments. Techniques include infrared and catalytic bead sensors, which must meet technical safety standards.
Preventive measures involve maintaining gas concentrations below the lower explosive limit (LEL) to prevent the formation of explosive atmospheres.
Conclusion
Gas-detection technology is vital for identifying and mitigating risks associated with hazardous gases and vapours. Understanding the properties of gases and vapours, atmospheric composition, and the principles of gas detection can help ensure safety in various industrial and environmental contexts.
This summary captures the essential information provided in the handbook regarding gas-detection technology and the properties and hazards of gases and vapours