The key difference between compressed gas and compressed air is that compressed gas contains natural gas, whereas compressed air contains a mixture of gases having a composition similar to atmospheric air.
The term “compressed” refers to flattened by pressure. In the case of gases, it describes the process of filling gas into cylinders under a pressure that is higher than the gas’s usual pressure. Compressed gas and compressed air are important sources of energy that can be used as fuel.
CONTENTS
1. Overview and Key Difference
2. What is Compressed Gas
3. What is Compressed Air
4. Side by Side Comparison – Compressed Gas vs Compressed Air in Tabular Form
5. Summary
What is Compressed Gas?
Compressed gas is a type of fuel that is made from pressurizing natural gas. It can be used in place of petrol, diesel fuel, and liquified petroleum gas (LPG). This fuel type forms fewer amounts of undesirable gases that are formed in higher amounts by petrol and other mentioned fuel types. Moreover, natural gas is less likely to spill due to its weight, which is lighter than air. It disperses immediately if released as a spill.
Generally, compressed natural gas is produced by compressing natural gas that contains methane at a higher percentage. In this process, natural gas is compressed to less than 1% of the volume it occupies at standard atmospheric pressure. This fuel is stored and distributed in hard containers at around 20-25 MPa pressure. These containers are typically cylindrical or in a spherical shape.
Figure 01: Compressed Gas as Fuel
Considering the applications of compressed gas, it is useful as fuels for motor vehicles and locomotives. We can convert any existing petrol vehicle into a dual-fuel petrol/compressed gas vehicle. This includes the installation of a compressed gas cylinder, plumbing, injection system, and electronics.
What is Compressed Air?
Compressed air is a gas mixture consisting of a composition similar to atmospheric air that is kept under high pressure than the usual atmospheric air pressure. This fuel is an important medium in transferring energy in industrial processes. Moreover, this fuel is useful for power tools, including air hammers, drills, wrenches and others. Furthermore, compressed air is useful as breathing gas for underwater diving. It’s used in diving cylinders or supplied from the surface under low pressure.
Figure 02: An Air Compressor
There are many other different uses of compressed air, including pneumatics, air tools, spray painting, vehicle propulsion, energy storage, air brakes such as railway braking systems, refrigeration with the use of vortex tube, air-start systems in engines, to clean dust and small debris in tiny places, etc.
What is the Difference Between Compressed Gas and Compressed Air?
Compressed gas and compressed air are important sources of energy that can be used as fuel. The key difference between compressed gas and compressed air is that compressed gas contains natural gas, whereas compressed air contains a mixture of gases having a composition similar to atmospheric air. Moreover, the pressure inside compressed gas is 200-250 bar while compressed air is 200-300 bar.
Below is a summary of the difference between compressed gas and compressed air in tabular form.
Summary – Compressed Gas vs Compressed Air
Compressed air and compressed gas are useful as fuel alternatives. The key difference between compressed gas and compressed air is that compressed gas contains natural gas, whereas compressed air contains a mixture of gases having a composition similar to atmospheric air.
Reference:
1. “Compressed Gases – Hazards.” Canadian Centre for Occupational Health and Safety, Government of Canada, 28 Mar. 2021, Available here.
Image Courtesy:
1. “Posto GNV 01 2009 485 CWB” By Mariordo Mario Roberto Duran Ortiz – Own work (CC BY 3.0) via Commons Wikimedia
2. “Single Stage Portable Air Compressor” By BSE9619 – Own work (CC BY-SA 4.0) via Commons Wikimedia