Gases under pressure are substances that are contained within a container at a certain pressure level, typically at or above a specified threshold. These gases are not just at normal atmospheric pressure; they've been compressed, liquefied, or both, to a much higher pressure.
Understanding Gases Under Pressure
Gases under pressure have specific characteristics defined by their containment and pressure. According to the information, gases under pressure are:
- Contained Gases: These are gases held within a receptacle or container.
- Pressure Threshold: The gas pressure inside the container is at least 200 kPa (kilopascals) or 29 psi (pounds per square inch gauge).
- State Variations: These include:
- Compressed gases
- Liquefied gases
- Dissolved gases
- Refrigerated liquefied gases
Types of Gases Under Pressure
Here's a breakdown of the different types, as mentioned:
| Type of Gas | Description |
|---|---|
| Compressed Gases | Gases that have been forced into a smaller volume, thus increasing the pressure inside the container. |
| Liquefied Gases | Gases that have been cooled and pressurized to a point where they change from gas into liquid. This often allows them to be stored in a smaller volume compared to their gaseous form. |
| Dissolved Gases | Gases that are dissolved in a liquid solvent, typically under pressure, which increases the amount of gas that can be dissolved in the liquid. |
| Refrigerated Liquefied Gases | Gases that have been liquefied and then kept at a very low temperature (refrigerated) to remain in liquid form; often needed because the liquid form is only stable at these cold temperatures. |
Why Gases are Stored Under Pressure
Gases are stored under pressure for a number of reasons, mainly to:
- Increase Storage Efficiency: By compressing or liquefying a gas, you can store much more of it in a smaller container.
- Enable Transportation: Gases are easier to transport in their compressed or liquefied form.
- Facilitate Industrial Processes: Many industrial processes require gases at certain pressures to function correctly.
- Power Systems: Many systems use compressed gases, like in pneumatic systems or gas-powered vehicles.
Examples of Gases Under Pressure
- Propane: Used for heating and cooking, typically stored as a liquefied gas under pressure.
- Oxygen: Used in hospitals for respiration and also for welding, commonly found as a compressed gas in cylinders.
- Carbon Dioxide: Used in fire extinguishers and for carbonating beverages; often stored as a compressed or liquefied gas.
- Nitrogen: Used in many industrial applications as a compressed gas.
Key Takeaways
Gases under pressure are gases that are compressed or liquefied and kept within a container at or above 200 kPa or 29 psi. They exist as compressed, liquefied, dissolved, or refrigerated liquefied gases, which makes them highly useful for many applications including storage, transportation, industrial use, and powering machinery.
