2. Chapter 16 Conditioning and Distribution of Compressed Air
Controlling Dirt, Moisture, Temperature, and Pressure

3. Objectives
Compare the various methods used to remove dirt from ambient air entering the compressor and in the final filtering of air distributed to the workstations.
Identify the benefits of controlling the temperature of compressed air and the methods used to remove excess heat.
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4. Objectives
Describe the problems caused by excess moisture in the compressed air of a pneumatic system.
Identify the source of moisture in a pneumatic system and various methods used to remove liquid water from a system.
Describe the functions of the pneumatic system receiver and identify construction features of typical designs.
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5. Objectives
Explain the factors that must be considered when establishing the size and location of a receiver for a pneumatic system.
Compare the various types of pipe, tubing, and hose used in pneumatic systems.
Identify and explain the factors that should be used when selecting a conductor for use in a pneumatic system.
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6. Objectives
Explain the design and construction of the various air distribution systems.
Describe the purpose, construction, and operation of the components used for the final preparation of compressed air at a pneumatic system workstation.
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7. Conditioning and Storing Pneumatic System Air
Maximum pneumatic system operating efficiency is achieved when system compressed air is:
Consistently clean
Free from moisture
At a relatively uniform temperature
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8. Conditioning and Storing Pneumatic System Air
Atmospheric air contains dirt under even the best of operating conditions
DeVilbiss Air Power Company
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9. Conditioning and Storing Pneumatic System Air
Pneumatic systems need to carefully filter the air taken into the compressor intake to extend the service life of
Compressor
Other system components
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10. Conditioning and Storing Pneumatic System Air
Correctly designed distribution system
IMI Norgren, Inc.
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11. Conditioning and Storing Pneumatic System Air
Filters used on the intake line of pneumatic compressors may be
Dry element
Oil wetted
Oil bath
The filter used is based on the type of compressor, atmospheric conditions, and the final use of the compressed air
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12. Conditioning and Storing Pneumatic System Air
Air at construction sites is dirty
Atlas Copco
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13. Conditioning and Storing Pneumatic System Air
Painting requires very clean air
DeVilbiss Air Power Company
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14. Conditioning and Storing Pneumatic System Air
The temperature of both the intake and compressed air is important
Temperature changes are reflected in air pressure and volume per the general gas law
Temperature influences the ability of air to retain water vapor
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15. Conditioning and Storing Pneumatic System Air
Air in a pneumatic system may be cooled before, during, or after compression
Intake air temperature usually depends on the location of the compressor air intake
Intercoolers and aftercoolers are used to remove heat of compression
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16. Conditioning and Storing Pneumatic System Air
Intercoolers cool compressed air between the stages of a multiple-stage compressor
Aftercoolers cool the air after the air has been compressed
Either air or water can be used as the cooling medium in these devices
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17. Conditioning and Storing Pneumatic System Air
Water vapor in air is referred to as humidity
Essential to our natural environment
Can cause problems in a pneumatic system when the temperature of the compressed air drops to the dew point and the vapor condenses into liquid water
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18. Conditioning and Storing Pneumatic System Air
Free air at 70° Fahrenheit can hold 1.14 pounds of water vapor per 1000 cubic feet
By volume, this water is equal to approximately one pint
Retention of water vapor in compressed air is based on the volume of air
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19. Conditioning and Storing Pneumatic System Air
Liquid water in a pneumatic system can:
Wash away lubricants
Increase component wear
Cause inconsistent system operation
Lower the finished quality of products directly using the air in the manufacturing process
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20. Conditioning and Storing Pneumatic System Air
Liquid water forms in system lines and components whenever the air temperature decreases to the dew point
The first step in reducing the liquid water in compressed air is to locate the atmospheric air intake of the compressor in a protected area
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21. Conditioning and Storing Pneumatic System Air
Condensation of the water vapor in compressed air can occur in:
Aftercooler units
Moisture separator
System receiver
Distribution system
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22. Conditioning and Storing Pneumatic System Air
Specific air driers can be used in pneumatic systems to remove moisture
Chemical desiccant
Refrigeration units
Specialized membranes
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23. Conditioning and Storing Pneumatic System Air
The receiver is the storage unit for compressed air
Typically, the receiver is a metal, cylindrical tank with domed ends
In addition to air storage, the receiver:
Dampens system pressure pulsations
Removes water vapor from system air
In smaller systems, serves as the mount for the prime mover and compressor
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24. Conditioning and Storing Pneumatic System Air
Formulas are available for calculating the volume needed for a receiver
These formulas consider:
Cubic feet of free atmospheric air needed per minute
Desired cycle time
Atmospheric, initial receiver, and final receiver air pressures
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25. Air-Distribution System
The air distribution system delivers high-pressure, conditioned air from the receiver to workstations with a minimum of pressure drop
The type of distribution system depends on the size of the facility and the level of demand for compressed air
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26. Air-Distribution System
Four general categories of air distribution systems are used with pneumatic systems
Centralized grid with fixed piping
Decentralized grid with fixed piping
Loop system with fixed piping
Flexible hoses for portable compressor systems
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27. Air-Distribution System
Centralized grid has one centralized compressor station and one line network for a facility
Decentralized grid has individual compressors in several locations providing air to smaller distribution networks
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28. Air-Distribution System
Centralized grid
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29. Air-Distribution System
Decentralized grid
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30. Air-Distribution System
Loop system has a main line that forms a continuous loop with compressors located at one or more locations
This design provides maximum airflow with a minimum of pressure drop between the compressors and the individual workstations
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31. Air-Distribution System
Loop system
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32. Air-Distribution System
Special attention must given to the setup of a hose air distribution in order to minimize pressure drop
Minimize hose length
Reduce the number of couplings
Eliminate kinks in the hose
Care must be taken to protect the hoses from abrasion in the work environment
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33. Air-Distribution System
Typical hose distribution system
DeVilbiss Air Power Company
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34. Air-Distribution System
Proper sizing of pipe for a fixed air distribution system is difficult
Most systems operate under a variety of work conditions:
Multiple workstations
Varying actuator loads
Intermittent actuator operation
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35. Air-Distribution System
Varying loads makes line sizing difficult
DeVilbiss Air Power Company
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36. Air-Distribution System
Sizing is based on:
Rated actuator air consumption
Estimate of the time actuators are actually operating
Estimate of the percentage of maximum load delivered during actuator operation
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37. Air-Distribution System
The pipe in air distribution lines should be installed with a pitch of 1 per 10 of line
Allows liquid water to drain to water traps
Water can be remove from traps either manually or with automatic drain devices
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38. Air-Distribution System
Drop lines lead from the main air distribution line to the workstations
Should be attached to the top side of the distribution line
This prevents water in the distribution lines from entering the workstation lines
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39. Air-Distribution System
Proper slope and drop line installation
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40. Final Preparation of Air at the Workstation
Final preparation of air at a workstation is accomplished by an FRL unit
Air filter
Pressure regulator
Lubricator
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41. Final Preparation of Air at the Workstation
Typical FRL unit
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42. Final Preparation of Air at the Workstation
FRL air filter removes:
Airborne dirt remaining in the atmospheric air compressed in the system
Rust and scale from the interior of the distribution lines
Liquid water that has condensed in the drop line
Atomized oil from the operating compressor
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43. Final Preparation of Air at the Workstation
Typical air filter uses centrifugal force and porous filter material to remove unwanted materials from system air
Inlet passageway swirls the incoming air, creating a centrifugal force that separates air and contaminants
Porous filter material traps other undesirable materials
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44. Final Preparation of Air at the Workstation
Typical FRL air filter
IMI Norgren, Inc.
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45. Final Preparation of Air at the Workstation
FRL filters typically have a drain
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46. Final Preparation of Air at the Workstation
The pressure regulator in an FRL unit reduces system distribution line pressure to the level needed by workstation tools and circuit actuators
Unit is also necessary as air pressure in the distribution line fluctuates due to varying air demands and the characteristics of compressor-capacity control
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47. Final Preparation of Air at the Workstation
Several regulator designs are available for use in a pneumatic system
Direct-operated regulator
Basic, diaphragm-chamber regulator
Relieving-type regulator
Balanced-poppet valve regulator
Pilot-operated regulator
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48. Final Preparation of Air at the Workstation
Regulators commonly use a flexible diaphragm to sense outlet line pressure and provide the balancing force needed to control airflow through a poppet valve
Only sufficient airflow to maintain the selected workstation pressure is allowed to pass through the poppet valve to the outlet port of the regulator
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49. Final Preparation of Air at the Workstation
Direct-operated pressure regulator
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50. Final Preparation of Air at the Workstation
Many regulators have a diaphragm-control chamber to separate the regulator side of the diaphragm from direct contact with distribution system air
Sensing orifice connects the control chamber and outlet port
This dampens the reaction of the diaphragm, providing more sensitive and efficient workstation pressure control
Protects diaphragm from contaminants
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51. Final Preparation of Air at the Workstation
Diaphragm-chamber regulator
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52. Final Preparation of Air at the Workstation
Some regulators contain a venting orifice located in the center of the diaphragm
Prevents pressure increase in the outlet port beyond the regulator pressure setting
The relieving action automatically bleeds air from the outlet port to the atmosphere
This design feature allows the regulator to act like a small relief valve
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53. Final Preparation of Air at the Workstation
Relieving-type pressure regulator
IMI Norgren, Inc.
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54. Final Preparation of Air at the Workstation
Balanced-poppet valve regulators have a design that subjects both ends of the valve poppet to equal air pressure
Allows the valve to be more accurately positioned
Produces better pressure control and improved response to system load variations
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55. Final Preparation of Air at the Workstation
Balanced-poppet valve pressure regulator
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56. Final Preparation of Air at the Workstation
Pilot-operated regulators have a sealed pilot-air chamber in place of a control spring and adjustment screw
A second, small, remotely located regulator is used to control air pressure in the pilot-air chamber
The air pressure in the pilot-air chamber acts as an air spring to establish the setting of the pilot-operated regulator
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57. Final Preparation of Air at the Workstation
Pilot-operated pressure regulator
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58. Final Preparation of Air at the Workstation
Installation of a pilot-operated pressure regulator with a secondary regulator
IMI Norgren, Inc.
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59. Final Preparation of Air at the Workstation
Factors to consider when selecting a system regulator are:
Regulator style
Pressure range
Airflow range
Conductor connection size
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60. Final Preparation of Air at the Workstation
The lubricator in an FRL unit meters oil into pressurized system air at the workstation
This provides lubrication for system valves, actuators, and air-powered tools
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61. Final Preparation of Air at the Workstation
Typical FRL lubricator
IMI Norgren, Inc.
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62. Final Preparation of Air at the Workstation
Rapidly moving system air passing through a lubricator breaks up droplets of oil, forming a mist or fog
This mist is transported through the workstation lines to system components
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63. Distribution System Conductors and Fittings
Effectively moving compressed air through a distribution system requires appropriate conductors and connectors
Conductors can be classified as
Rigid
Flexible
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64. Distribution System Conductors and Fittings
Pipe is the most common rigid conductor
Hose is the most common flexible conductor
Conductors must be properly sized and assembled for compressed air to be transported from the compressor to actuators with minimal pressure drop
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65. Distribution System Conductors and Fittings
Conductors and the associated fittings must be properly sized
IMI Norgren, Inc.
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66. Distribution System Conductors and Fittings
Tables are available that provide data on air pressure loss in standard rigid and flexible conductor sizes using various flow rates
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67. Distribution System Conductors and Fittings
Various types of hose are available
Atlas Copco
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68. Distribution System Conductors and Fittings
Hose selection, application, and maintenance are critical to assure air distribution with a minimum loss of pressure
Hoses should be no longer than necessary
Hoses should be no larger than necessary
Use a minimum number of fittings
Layout lines to eliminate kinks and reduce the number of bends
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69. Distribution System Conductors and Fittings
Proper hose selection is important
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70. Review Question
Name five materials that may be used to make the element in a dry filter for use in pneumatic systems.
A. Paper, B. plastic, C. cloth, D. metal, and E. ceramic.
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71. Review Question
_____ is the temperature at which water vapor in the air begins to condense to form liquid water.
Dew point
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72. Review Question
Name five places where liquid water may form in the pneumatic system.
A. Intercooler, B. aftercooler, C. moisture separator, D. receiver, and E. system distribution lines.
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73. Review Question
Name two things that occur when warm, humid, high-pressure air cools in the distribution lines of a pneumatic system.
A. The pressure of the air reduces according to the general gas law, and B. liquid water forms when the dew point of the air is reached.
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74. Review Question
In addition to air storage, the receiver dampens air _____ caused by compressor operation.
pulsations
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75. Review Question
What can be used to supply compressed air to a section of the distribution system that contains equipment using a large volume of air on an intermittent basis without increasing the size of the system?
An auxiliary receiver.
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76. Review Question
What is the most common rigid conductor for major pneumatic systems?
Pipe.
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77. Review Question
Identify two factors that are critical to selecting the actual sizes of the lines used in an air distribution system.
A. Anticipated airflow rate through the lines, and B. pressure drop caused by the lines and fittings.
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78. Review Question
The _____ compressed-air-distribution system distributes air from a single location to all workstations in a facility.
centralized grid
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79. Review Question
Why is it necessary to use a pressure regulator in the final air preparation unit at a system workstation?
Air pressure in the distribution lines is higher than what is needed for operation of the workstation actuators. Also, the pressure in the distribution lines varies considerably because of the way the compressor-capacity control system functions.
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80. Glossary Aftercooler Centralized grid
A pneumatic system heat exchanger that cools compressed air as it leaves the compressor; used to both cool air and liquefy water vapors.
Centralized grid
An air-distribution system consisting of a network of branch lines extending from a central trunk line. The branch lines supply workstations located throughout a facility.
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81. Glossary Decentralized grid
An air-distribution system consisting of multiple grids that serve small portions of a facility. These grid sections contain smaller compressors, but may be interconnected to provide air movement between grids to balance intermittent, high air demands.
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82. Glossary Desiccant Dew point
A material in compressed-air dryers that uses the principle of adsorption to remove moisture from the air.
Dew point
The temperature at which the water vapors in air will begin to condense (form dew).
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83. Glossary Diaphragm-chamber regulator Direct-operated regulator
A pneumatic system regulator that uses a flexible diaphragm between the outlet and control chambers of the valve.
Direct-operated regulator
A basic design of a pneumatic system pressure regulator in which the diaphragm is directly exposed to the pressure of the outlet chamber.
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84. Glossary
Drop line
A pipe coming from the top of the air distribution lines to a system workstation. Tapping the line into the top of the distribution line prevents condensed water from entering the drop line.
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85. Glossary Flexible hose FRL unit
Hoses used in both hydraulic and pneumatic systems that can operate under full system pressure while providing maximum freedom of movement.
FRL unit
A component group providing air filtration, pressure regulation, and lubrication for a specific pneumatic system workstation.
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86. Glossary
Intercooler
A heat exchanger located between the stages of a two-stage pneumatic compressor. The intercooler reduces the temperature of the compressed air, thus increasing the performance of the compressor.
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87. Glossary Loop system Lubricator
One style of air-distribution system. The distribution line forms a continuous loop with workstations located at several points along the line.
Lubricator
A device designed to apply a lubricant to a bearing surface. In pneumatic systems, the lubricator is a component of the FRL unit located at the workstation.
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88. Glossary Moisture separator Pilot-operated regulator
A device sometimes teamed with the compressor aftercooler to increase the effectiveness of the moisture-removal process during pneumatic system air compression.
Pilot-operated regulator
A pneumatic system pressure regulator that is controlled by pilot pressure from a remote location.
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89. Glossary Pressure regulator
A pneumatic system component used to control air pressure at the system workstations. The valve maintains a constant, reduced pressure for use by tools and equipment operated at the station.
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90. Glossary Relieving-type regulator
A pneumatic system pressure regulator that contains a venting orifice. The vent prevents system pressure from exceeding the initial setting of the regulator, even when downstream conditions cause an increase in air pressure.
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