Permission granted to reproduce for educational use only. Describe the problems caused by excess

Transcription

1 Chapter 16 Conditioning and Distribution of Compressed Air Controlling Dirt, Moisture, Temperature, and Pressure 1

2 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. Goodheart-Willcox Co., Inc. 3 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. Goodheart-Willcox Co., Inc. 4 2

3 Objectives Explain the factors that must be considered when establishing the size and dlocation 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. Goodheart-Willcox Co., Inc. 5 Objectives Explain the design and construction of the various air distribution ib ti systems. Describe the purpose, construction, and operation of the components used for the final preparation of compressed air at a pneumatic system workstation. Goodheart-Willcox Co., Inc. 6 3

4 Conditioning and Storing Pneumatic System Air Maximum pneumatic system operating efficiency i is achieved when system compressed air is: Consistently clean Free from moisture At a relatively uniform temperature Goodheart-Willcox Co., Inc. 7 Conditioning and Storing Pneumatic System Air Atmospheric air contains dirt under even the best of operating conditions DeVilbiss Air Power Company Goodheart-Willcox Co., Inc. 8 4

5 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 Goodheart-Willcox Co., Inc. 9 Conditioning and Storing Pneumatic System Air Correctly designed distribution system IMI Norgren, Inc. Goodheart-Willcox Co., Inc. 10 5

6 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 Goodheart-Willcox Co., Inc. 11 Conditioning and Storing Pneumatic System Air Air at construction sites is dirty Atlas Copco Goodheart-Willcox Co., Inc. 12 6

7 Conditioning and Storing Pneumatic System Air Painting requires very clean air DeVilbiss Air Power Company Goodheart-Willcox Co., Inc. 13 Conditioning and Storing Pneumatic System Air The temperature of both the intake and compressed air is important t Temperature changes are reflected in air pressure and volume per the general gas law Temperature influences the ability of air to retain water vapor Goodheart-Willcox Co., Inc. 14 7

8 Conditioning and Storing Pneumatic System Air Air in a pneumatic system may be cooled bf 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 Goodheart-Willcox Co., Inc. 15 Conditioning and Storing Pneumatic System Air Intercoolers cool compressed air between the stages of a multiple-stage l t 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 Goodheart-Willcox Co., Inc. 16 8

9 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 Goodheart-Willcox Co., Inc. 17 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 Goodheart-Willcox Co., Inc. 18 9

10 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 gprocess Goodheart-Willcox Co., Inc. 19 Conditioning and Storing Pneumatic System Air Liquid water forms in system lines and components whenever the air temperature t 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 Goodheart-Willcox Co., Inc

11 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 Goodheart-Willcox Co., Inc. 21 Conditioning and Storing Pneumatic System Air Specific air driers can be used in pneumatic systems to remove moisture Chemical desiccant Refrigeration units Specialized membranes Goodheart-Willcox Co., Inc

12 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 Goodheart-Willcox Co., Inc. 23 Conditioning and Storing Pneumatic System Air Formulas are available for calculating the volume needed dfor 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 Goodheart-Willcox Co., Inc

13 Air-Distribution System The air distribution system delivers high- pressure, conditioned d 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 Goodheart-Willcox Co., Inc. 25 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 Goodheart-Willcox Co., Inc

14 Air-Distribution System Centralized grid has one centralized compressor station ti and one line network for a facility Decentralized grid has individual compressors in several locations providing air to smaller distribution networks Goodheart-Willcox Co., Inc. 27 Air-Distribution System Centralized grid Goodheart-Willcox Co., Inc

15 Air-Distribution System Decentralized grid Goodheart-Willcox Co., Inc. 29 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 Goodheart-Willcox Co., Inc

16 Air-Distribution System Loop system Goodheart-Willcox Co., Inc. 31 Air-Distribution System Special attention must given to the setup of a hose air distribution ib ti in order to minimize i i 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 Goodheart-Willcox Co., Inc

17 Air-Distribution System Typical hose distribution ib ti system DeVilbiss Air Power Company Goodheart-Willcox Co., Inc. 33 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 Goodheart-Willcox Co., Inc

18 Air-Distribution System Varying loads makes line sizing i difficult DeVilbiss Air Power Company Goodheart-Willcox Co., Inc. 35 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 Goodheart-Willcox Co., Inc

19 Air-Distribution System The pipe in air distribution lines should be installed with a pitch of f1 per 10 of fline Allows liquid water to drain to water traps Water can be remove from traps either manually or with automatic drain devices Goodheart-Willcox Co., Inc. 37 Air-Distribution System Drop lines lead from the main air distribution line to the workstations ti Should be attached to the top side of the distribution line This prevents water in the distribution lines from entering the workstation lines Goodheart-Willcox Co., Inc

20 Air-Distribution System Proper slope and drop line installation Goodheart-Willcox Co., Inc. 39 Final Preparation of Air Final preparation of air at a workstation is accomplished by an FRL unit Air filter Pressure regulator Lubricator Goodheart-Willcox Co., Inc

21 Final Preparation of Air Typical FRL unit Goodheart-Willcox Co., Inc. 41 Final Preparation of Air 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 Goodheart-Willcox Co., Inc

22 Final Preparation of Air 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 Goodheart-Willcox Co., Inc. 43 Final Preparation of Air Typical FRL air filter IMI Norgren, Inc. Goodheart-Willcox Co., Inc

23 Final Preparation of Air FRL filters typically have a drain Goodheart-Willcox Co., Inc. 45 Final Preparation of Air The pressure regulator in an FRL unit reduces system distribution ib ti line pressure to the level l 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 compressorcapacity control Goodheart-Willcox Co., Inc

24 Final Preparation of Air 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 Goodheart-Willcox Co., Inc. 47 Final Preparation of Air Regulators commonly use a flexible diaphragm to sense outlet tline 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 Goodheart-Willcox Co., Inc

25 Final Preparation of Air Direct-operated pressure regulator lt Goodheart-Willcox Co., Inc. 49 Final Preparation of Air 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 Goodheart-Willcox Co., Inc

26 Final Preparation of Air Diaphragm-chamber regulator Goodheart-Willcox Co., Inc. 51 Final Preparation of Air 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 Goodheart-Willcox Co., Inc

27 Final Preparation of Air Relieving-type pressure regulator lt IMI Norgren, Inc. Goodheart-Willcox Co., Inc. 53 Final Preparation of Air Balanced-poppet valve regulators have a design that t 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 Goodheart-Willcox Co., Inc

28 Final Preparation of Air Balanced-poppet valve pressure regulator Goodheart-Willcox Co., Inc. 55 Final Preparation of Air 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 pilotoperated regulator Goodheart-Willcox Co., Inc

29 Final Preparation of Air Pilot-operated pressure regulator Goodheart-Willcox Co., Inc. 57 Final Preparation of Air Installation of a pilottdpressure regulator with a operated secondary regulator IMI Norgren, Inc. Goodheart-Willcox Co., Inc

30 Final Preparation of Air Factors to consider when selecting a system regulator lt are: Regulator style Pressure range Airflow range Conductor connection size Goodheart-Willcox Co., Inc. 59 Final Preparation of Air The lubricator in an FRL unit meters oil into pressurized system air at tthe workstation ti This provides lubrication for system valves, actuators, and air-powered tools Goodheart-Willcox Co., Inc

31 Final Preparation of Air Typical FRL lubricator IMI Norgren, Inc. Goodheart-Willcox Co., Inc. 61 Final Preparation of Air 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 Goodheart-Willcox Co., Inc

32 Distribution System Conductors and Fittings Effectively moving compressed air through a distribution ib ti system requires appropriate conductors and connectors Conductors can be classified as Rigid Flexible Goodheart-Willcox Co., Inc. 63 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 Goodheart-Willcox Co., Inc

33 Distribution System Conductors and Fittings Conductors and the associated fittings must be properly sized IMI Norgren, Inc. Goodheart-Willcox Co., Inc. 65 Distribution System Conductors and Fittings Tables are available that provide data on air pressure loss in standard drigid idand dflexible conductor sizes using various flow rates Goodheart-Willcox Co., Inc

34 Distribution System Conductors and Fittings Various types of hose are available Atlas Copco Goodheart-Willcox Co., Inc. 67 Distribution System Conductors and Fittings Hose selection, application, and maintenance are critical to assure air distribution ib ti 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 Goodheart-Willcox Co., Inc

35 Distribution System Conductors and Fittings Proper hose selection is important Goodheart-Willcox Co., Inc. 69 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. Goodheart-Willcox Co., Inc

36 Review Question is the temperature at which water vapor in the air begins to condense to form liquid id water. Dew point Goodheart-Willcox Co., Inc. 71 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. Goodheart-Willcox Co., Inc

37 Review Question Name two things that occur when warm, humid, high-pressure h 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. Goodheart-Willcox Co., Inc. 73 Review Question In addition to air storage, the receiver dampens air caused dby compressor operation. pulsations Goodheart-Willcox Co., Inc

38 Review Question What can be used to supply compressed air to a section of the distribution ib ti system that t contains equipment using a large volume of air on an intermittent basis without increasing the size of the system? An auxiliary receiver. Goodheart-Willcox Co., Inc. 75 Review Question What is the most common rigid conductor for major pneumatic systems? Pipe. Goodheart-Willcox Co., Inc

39 Review Question Identify two factors that are critical to selecting the actual sizes of fthe lines used in an air distribution system. A. Anticipated airflow rate through the lines, and B. pressure drop caused by the lines and fittings. Goodheart-Willcox Co., Inc. 77 Review Question The compressed-air-distribution system distributes ib t air from a single location to all workstations in a facility. centralized grid Goodheart-Willcox Co., Inc

40 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. Goodheart-Willcox Co., Inc. 79 Glossary Aftercooler 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. Goodheart-Willcox Co., Inc

41 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. Goodheart-Willcox Co., Inc. 81 Glossary Desiccant 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). Goodheart-Willcox Co., Inc

42 Glossary Diaphragm-chamber regulator A pneumatic system regulator that tuses 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. Goodheart-Willcox Co., Inc. 83 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. Goodheart-Willcox Co., Inc

43 Glossary Flexible hose 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. Goodheart-Willcox Co., Inc. 85 Glossary Intercooler Ah heat exchanger located dbetween the stages of a two-stage pneumatic compressor. The intercooler reduces the temperature of the compressed air, thus increasing the performance of the compressor. Goodheart-Willcox Co., Inc

44 Glossary Loop system One style of air-distribution ib ti 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. Goodheart-Willcox Co., Inc. 87 Glossary Moisture separator 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. Goodheart-Willcox Co., Inc

45 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. Goodheart-Willcox Co., Inc. 89 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. Goodheart-Willcox Co., Inc