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Questions and Answers
Which of the following is a direct application of pneumatics, as defined in the provided content?
Which of the following is a direct application of pneumatics, as defined in the provided content?
- Harnessing solar radiation to generate electricity.
- Converting compressed air pressure into mechanical work. (correct)
- Utilizing geothermal energy to power turbines.
- Employing chemical reactions to produce kinetic energy.
A factory is considering switching to a pneumatic system. Which of the following is a potential disadvantage they should consider?
A factory is considering switching to a pneumatic system. Which of the following is a potential disadvantage they should consider?
- Pneumatic systems are inherently explosion-proof, reducing safety concerns.
- Compressed air systems require thorough preparation to avoid issues with dirt and humidity. (correct)
- Pneumatic systems are cost-effective at any pressure level.
- Pneumatic systems are easily adjustable, allowing for infinitely variable speeds and forces.
If the volume of a gas is doubled while maintaining a constant temperature, what happens to the pressure according to Boyle's Law?
If the volume of a gas is doubled while maintaining a constant temperature, what happens to the pressure according to Boyle's Law?
- The pressure is halved. (correct)
- The pressure doubles.
- The pressure is quadrupled.
- The pressure remains constant.
In a pneumatic system, which component is responsible for directing air to different parts of an actuator to control its movement?
In a pneumatic system, which component is responsible for directing air to different parts of an actuator to control its movement?
A manufacturing plant wants to use compressed air for a new application. Which characteristic of compressed air makes it suitable for tasks requiring fast and repetitive actions?
A manufacturing plant wants to use compressed air for a new application. Which characteristic of compressed air makes it suitable for tasks requiring fast and repetitive actions?
Which component is essential for removing dust and other impurities from the incoming air in a pneumatic system?
Which component is essential for removing dust and other impurities from the incoming air in a pneumatic system?
A compressed air system is operating in an environment where the temperature fluctuates significantly. Which characteristic of compressed air minimizes concerns related to these temperature changes?
A compressed air system is operating in an environment where the temperature fluctuates significantly. Which characteristic of compressed air minimizes concerns related to these temperature changes?
A pneumatic system in a woodworking shop releases air into the environment. Why is it necessary to consider sound absorption materials around the exhaust?
A pneumatic system in a woodworking shop releases air into the environment. Why is it necessary to consider sound absorption materials around the exhaust?
Which type of air compressor is most likely to be found in applications requiring extremely clean compressed air, such as in the food or pharmaceutical industries?
Which type of air compressor is most likely to be found in applications requiring extremely clean compressed air, such as in the food or pharmaceutical industries?
A large manufacturing plant needs to select an air compressor. Which factor is most important when determining the appropriate size and capacity of the compressor?
A large manufacturing plant needs to select an air compressor. Which factor is most important when determining the appropriate size and capacity of the compressor?
Flashcards
What is pneumatics?
What is pneumatics?
Engineering branch using compressed air to perform mechanical work.
What does an air filter do?
What does an air filter do?
Removes dust and impurities from the air.
What's the role of air compressor?
What's the role of air compressor?
Compresses air to increase its pressure.
What is the purpose of an Aftercooler?
What is the purpose of an Aftercooler?
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What are positive characteristics of compressed air?
What are positive characteristics of compressed air?
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Compressor pressure?
Compressor pressure?
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What happens during air intake and compression?
What happens during air intake and compression?
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How is compressed air used?
How is compressed air used?
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Types of displacement compressors?
Types of displacement compressors?
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Types of flow compressors?
Types of flow compressors?
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Study Notes
- Pneumatics comes from the Greek word "pneuma" - breath or wind
- It changes compressed air pressure into mechanical work
- Compressed air is hot due to the forced proximity of its molecules
Development of Compressed Air Engineering
- 3000 BC: Sumerians used bellows to control fire
- Hero of Alexandria invented an air powered device to open doors
- Robert Boyle created Boyle's Law in the 17th C - Volume of gas is inversely proportional to its pressure at a constant temperature
- Otto von Guericke invented the air pump to show atmospheric pressure
- Ctesibius first studied pneumatics and air powered devices
Components of Pneumatic System
- Air filter removes dust
- Air compressor increases air pressure
- Motor powers the compressor through electricity
- Air cooler removes excess heat from compressed air
- Storage reservoir stores compressed air
- Pressure switch monitors pressure
- Directional control valve directs air
- Off Position - no air
- Raise Position - air flows to chamber B, lifting load
- Lower Position - air flows to chamber A, lowering load
- Air actuator converts compressed air to mechanical movement
- Load is the object being moved
- Air-to-atmosphere ports release used air
Characteristics of Compressed Air
- Amount - Unlimited
- Transportable with pipelines
- Storable in a reservoir
- Temperature insensitive
- Explosion proof
- Clean
- Simple construction
- Fast working medium
- Adjustable speeds and forces
- Overload safe
Negative Characteristics of Compressed Air
- Needs good preparation and is affected by dirt or humidity
- Compressible, making uniform speeds unachievable
- Only economical to certain pressure levels, 7 bar (101.5 psi) typically
- Exhaust is loud, though sound absorption materials have largely fixed this
- Power costs to compress can be significant
Compressed Air Cost Formula
- Cost (PHP) = (bhp)(0.746)(# of op. hr) (kWh) (% time)(% full – load bhp) / Motor Efficiency
Physical Fundamental Principles
- Air Composition – 78% Nitrogen, 21% Oxygen, ~1% Other gases
- Laws - Newton’s Law: F = ma, Boyle’s Law: P1V1 = P2V2, Gay-Lussac’s Law: V1/V2=T1/T2, General Gas Equation: P1V1/T1=P2V2/T2
- Effects of temperature - air expands 1/273 when heated by 1K.
- Equation of gases: PV = nRT
- Pressure and Volume changes are predictable
- Pressure Measurements
- 1 at (atmosphere) = 1 kp/cm^2 = 0.981 bar (98.1 kPa)
- 1 Pa (pascal) = 1 N/m^2 = 10^-5 bar , 1 bar = 10^5 N/m^2 = 10^5 pa = 1.02 at
- 1 atm = 1.033 at = 1.013 bar (101.3 kPa)
- 10 000 mm WG = 1 at = 0.981 bar (98.1 kPA)
- 1 mm hg = 1 Torr and 1 at = 736 Torr, 1 bar = 750 Torr
Basic Air Compressor System in Modern Industries
- Air Inlet Filter
- Lubricant / Air Separator
- Compressor Air End
- Motor
- Control Panel
- Aftercooler and Lubricant Cooler
- Moisture Separator
- Dryer
- Air Filter
- Air Receiver
- Pressure-Flow Controller
- Distribution System
- Air Intake & Compression
Air Treatment, Storage, and Usage
- Air Treatment and Drying removes contaminates
- Air Storage & Regulation uses a receiver
- Air Distribution & Usage goes through pipelines
Uses of Compressed Air in Industries
- Automation: Powers assembly lines and robots
- Assembly lines: Powers hand-held tools
- Cooling Processes: cools parts in situations of machining
- Control Systems: Operates automated valves and actuators
Types of Compressors
- Displacement Compressors
- Reciprocating Piston Compressors - The most used and positive-displacement ,and range in pressure (1 bar / 14.5 psi)++
- Diaphragm Compressors - Uses a flexible diaphragm to compress air and prevents contamination
- Rotary Piston Compressors - Includes sliding vane, two-axle screw, and Roots blower types
- Flow Compressors (Turbocompressors)
- Axial Compressors - use blades to compress air - common in jet engines
- Radial Compressors - use impeller– common with gas
Selection Criteria for Compressors
- Delivery Volume - amount delivered (m³/min or m³/h).
- Pressure - (6 bar or 87 psi)
- Drive Type - Either electric motors or internal combustion engines.
- Regulation Methods -
- No Load
- Exhaust - works against a pressure relief valve
- Shut-off - cannot draw air in
- Grip-arm - used on piston compressors
- Low Seed with Throttling
- Cooling Methods – Either air-cooled or water-cooled.
- Install in well ventilated, dry sites
- Compressed Air Receivers stabilize pressure
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