LESSON 3: ENERGY TRANSMISSION USING

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LESSON 3 ENERGY TRANSMISSION USING
A PNEUMATIC SYSTEM
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Gases

• Are made of moving molecules that are not readily
  attracted to one another.
• The molecules must be restrained or they will
  disperse because of their molecular energy and
  lack of restraining forces.
• Take the shape of their container. Much of that
  volume is empty space.

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HEAT ENERGY

• Solid found as vibrating molecules
• Liquid molecules slip and slide past one
  another higher temperatures produces quicker
  molecular movement.
• Gas molecules are continuously moving which
  creates this heat energy. Increasing temperature
  causes faster moving molecules.

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IDEAL GAS LAW

• P1V1 P2V2
• T1 T2
• Pressure and temperature are proportional to each
  other.
• When volume increases both temperature and
  pressure will decrease, and vice versa.

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PNEUMATIC TRANMISSION OF ENERGY

• Machines use energy to perform work.
• Pneumatic systems do work when the potential
  energy of compressed air is converted into
  kinetic energy.
• When a valve on a tank outlet is opened the gas
  will flow until the tank pressure equals
  atmospheric pressure. The escaping air has
  kinetic energy. Hence the conversion from
  potential to kinetic.

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POSITIVE DISPLACEMENT COMPRESSOR

• A type of device that will deliver a sufficient
  amount of air at a desired pressure.
• Delivers compressed air to an air receiver tank.
• When pressure differential between the cylinder
  compressor chamber and the discharge line gets
  high enough a valve opens, and air flows into the
  receiver tank for storage.

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INEFFICEINCIES OF A PNEUMATIC SYSTEM

• Loss of heat during air compression as the air
  is compressed the temperature rises but after
  time that heat dissipates through container walls
  thus decreasing some of the pressure or potential
  energy.
• Friction occurs when elements are moving in
  relation to one another. The air moves with
  respect to the pipe containing it.
• Fluid changing direction air molecules crash
  into surfaces and each other as it is forced to
  change direction such as at an elbow, this causes
  a decrease in pressure energy.

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FLOW RATE

• The volume of air flowing through a pipe.
• Measured in cubic feet per minute (CFM)
• CFM is a cubic foot of air at the compressor
  intake. This distinction is made due to the
  volume variation that occurs in gases at
  different pressures.

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FREE VS. STANDARD AIR

• Free air the condition of the air supply
  available to a compressor.
• Standard air air at a barometric pressure of
  29.92 in. (sea level), temp of 68o F and relative
  humidity of 36
• Free air is usually converted mathematically to a
  cubic foot of standard air because of the varying
  atmospheric conditions from day to day.

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VELOCITY

• Air flows through a system at a certain speed.
• This speed is measured in feet per second (FPS).
• Critical velocity the maximum velocity at which
  air exists in an air system. At normal temps
  this is about 1100 FPS and is important when
  response times are critical (53 differential).

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PNEUMATIC SYSTEM DESIGN

• Energy must be used with care.
• Should be designed with correctly sized pipes and
  components.
• Bends and elbows kept to a minimum so that
  pressure is not unnecessarily wasted.
• Compressor must be of appropriate size and type.