File Name: industrial hydraulics and pneumatics book .zip
Most curricular materials in TeachEngineering are hierarchically organized; i. Some activities or lessons, however, were developed to stand alone, and hence, they might not conform to this strict hierarchy. Related Curriculum shows how the document you are currently viewing fits into this hierarchy of curricular materials. Figure 1. Once they understand how the system operates and put it together, they use it to try to move specific pieces of material.
Tel: Fax: Pneumatic and hydraulic systems have been used for many years within industrial processes and as such have acquired an established place in modern industry. Continuous development of fluid power technology over the years has significantly expanded and increased the applications to many areas hitherto not known for adopting pneumatic and hydraulic technology.
More recent users have been in the fields of offshore oil and gas development, space and aeronautical systems and nuclear applications. Often, pneumatics and hydraulics are combined with other technologies such as mechanical, electrical and electronic systems to form an overall system.
An example of this can be found in robotics. Some general methods of material handling used in industry, for example, may be: 2 Controlling processes and plant. Pneumatic and hydraulic systems may be used to sense the operational status of a process, feed this information back to a controller which will take a necessary control action, for example a limit switch may sense that an actuator needs to be operated.
Pneumatics and hydraulics can be used to provide measurements of process or machine parameters, act on this information and subsequently display it to an operator. In addition to operating, controlling and measuring parameters of process plant and machinery, hydraulics and pneumatics may be used in high integrity safety systems.
This is expanded further in Chapter The high speed and reliability of operation embodied in good modem pneumatic and hydraulic system design coupled with inherent explosion-proof and overload-safe operation makes the choice of this technology ideal for applications in the marine, offshore and petro-chemical industries. Figure 1. Such a system can bring a vehicle to a halt literally within centimetres once an obstruction is encountered.
The surface of the Earth is covered entirely by layers of air. There are also small amounts of water vapour and carbon dioxide together with traces of the 'rare gases': argon, krypton, xenon, neon and helium. When air is compressed and stored it can be used as a medium for making measurements and for controlling and operating equipment and plant. This is known as pneumatics. In hydraulic systems, the compressed air is replaced with a liquid-based solution, typically oil, which is used under pressure to perform measurements and to control and operate plant and machinery.
Hydraulic systems tend to operate at much higher pressures than pneumatic systems and consequently can produce larger forces. Over the years the performance standards of hydraulic equipment have risen. Whereas a pressure of about 70 bar used to be adequate for industrial hydraulic systems, nowadays systems operating with pressures of to bar are common. In certain applications pressures in excess of bar are used, for example large industrial presses, offshore petro-chemical installations, etc.
Also, it should be noted that sometimes manufacturers produce a piece of pneumatic or hydraulic equipment which cannot be exactly represented by existing symbols, in which case the manufacturer develops its own symbol. The following shows the more commonly applied BS symbols. A more detailed description of the symbols relating to fluid power generation, distribution, supply equipment, valves and actuation will be given in later chapters.
AimsAt the end of this chapter you should be able to:1 Appreciate the arrangement and type of plant and equipment required for fluid power generation and supply.
The preparation of the air starts from the point of generation. Contamination of the air can occur at many potential points in the generation and distribution system right up to the point of use. There is little point in preparing good quality air and then allowing incorrect component and equipment selection to reduce the quality. Positive displacement compressorsPositive displacement compressors are those in which successive volumes of air are confined within a closed space and elevated to a higher pressure.
The capacity of a positive displacement compressor varies marginally with the working pressure. Reciprocating compressorsThe compressing and displacing element piston and diaphragm has a reciprocating motion.
The piston compressor is available in lubricated and non-lubricated construction. Helical and spiral-lobe compressors screw Rotary, positive displacement machines in which two inter-meshing motors, each in helical configuration, displace and compress the air. Available in lubricated and non-lubricated construction.
The discharge air is normally free from pulsation; operates at high rotation speed. Sliding-vane compressorsRotary, positive displacement machines in which axial vanes slide radially in a rotor which is mounted eccentrically within a cylindrical casing. Available in lubricated and non-lubricated construction; the discharge air is normally free from pulsation. Two impeller straight-lobe compressors and blowersRotary, positive displacement machines in which two straight, mating but non-touching lobed impellers trap the air and carry it from intake to discharge.
The discharge is normally free from pulsation. Operates at low pressure and high rotation speed. Dynamic compressorsDynamic compressors are rotary continuous flow machines in which the rapidly rotating element accelerates the air as it passes through the element, converting the velocity head into pressure, partially in the rotating element and partially in stationary diffusers or blades.
The capacity of a dynamic compressor varies considerably with the working pressure. The most common industrial type of air compressor is still the reciprocating machine, although screw and vane types are finding increasing application, as also are turbo units in the larger sizes. Some types of compressor can be supplied in 'oil-free' form.
In these machines, no oil is allowed to enter the compression chamber and the following basic modifications are introduced. In a reciprocating compressor where the piston is sealed with piston rings, the materials are changed from the normal cast-iron ring which requires oil for lubrication, to either carbon graphite or PTFE.
PTFE is a self-lubricating material which will withstand the pressures and mechanical forces involved in the running of the compressor whilst carbon graphite uses the moisture in compressed air as the lubricant.
In a screw compressor the clearances between the mating male and female rotors are adjusted so that there is no metal-to-metal contact. The rotary vane or sliding vane machine is often described as an 'oil-flooded' unit. Quite large quantities of oil are injected into the incoming air and pass right through the compression chamber with the air. The oil not only seals the vanes against the periphery of the compression space but also acts as a lubricant and as a means of removing a fair amount of the heat generated.
This oil is then reclaimed from the compressed air by means of separators, cooled and re-circulated. This type of machine has the added advantage of being very quiet in operation.
With any lubricated compressor a certain amount of oil is bound to be carried over into the compressed air system. Provided that air-line filters are used, the amount of such oil is generally not enough to cause trouble in most industrial applications.
Air preparation and service units comprising filters, regulators and lubricators are discussed later in this chapter. This consists of twin containers holding a solid chemical with the texture of a fine honeycomb or sponge. This texture gives it a large surface area to which the water droplets will cling. The water is adsorbed onto the surface, leaving the chemical unchanged, instead of being absorbed into the chemical to form a solution as in the chemical absorption dryer.
Since the chemical remains unchanged it can be regenerated by heating or by blowing dry air through it. The operation of the dryer is shown in Figure 5. With valves V in the position shown, the air flows through the vessel A where it is dried. Most of it passes to the outflow but, with valves c and d open, b and e closed, about 10 per cent of the air is bled off to vessel B to re-activate the chemical there.
Before the chemical in A becomes saturated, all the valves are switched to their other position, so that the main flow is through B while the dry air purge re-activates A.
The change-over is usually arranged to take place automatically on a time-cycle basis. Dryers, of whatever type, should be used on air that has already passed through an after-cooler, since otherwise the amount of work demanded from them will be excessive.
When the air is to be used for some purpose, for instance in the food processing industry, it is important that any oil vapour in it should be removed. Refrigeration dryers automatically reduce the oil vapour concentration at the same time as removing moisture, but oil vapour may also be removed in special units containing chemicals for this purpose. We have described the effectiveness of the different types of dryer by quoting what is known as the 'pressure dew point', that is the temperature to which the air in the pipeline at working pressure can cool before moisture will settle out.
Some manufacturers, however, quote the 'atmospheric dew point' for their plant instead, that is the dew point which the air coming from the dryer would have if it were expanded to atmospheric pressure. Caution is needed in interpreting such a figure, as an example will show.
From Table 5. Therefore 0. If we allow the 0. By interpolation we find that at So what does this tell us? But a more important point is that, if the manufacturer has quoted the atmospheric dew point and the air is to be used out of doors in winter conditions, we might be tempted to suppose that there is no danger of instrument freezing unless the temperature drops to The catch is that this argument only applies to the air after it has been discharged.
This change would have bad little effect, since the absolute temperature drops from K to The use of manual drain cocks, as shown in Figure 5. If they are forgotten they can cause all the liquids which have been separated out of the air to be re-entrained and carried over into the system with possible breakdown of pneumatic equipment and spoilage of product, both of which can be very expensive.
It makes sense, therefore, to use some sort of automatic device which will release any liquid but remain closed to air. There are a number available on the market, each having its own particular characteristics as follows. The advantage of the float-operated type is that it is simple and positive.
The disadvantage is that, because of the mechanical force needed to open the valve, the discharge orifice has to be small, particularly the directly operated float type, and it can easily get blocked by the dirt, silt or gum which are so often found in compressed air systems. This type of trap may also be unable to deal with foam which sometimes comes over from compressors and may not be dense enough to lift the float.
This is frequently accomplished by means of electrical equipment such as motors or solenoids , or via devices driven by air pneumatics or liquids hydraulics. This book has been written by a process control engineer as a guide to the operation of hydraulic and pneumatic systems for all engineers and technicians who wish to have an insight into the components and operation of such a system. This second edition has been fully updated to include all recent developments such as the increasing use of proportional valves, and includes an extra expanded section on industrial safety. It will prove indispensable to all those wishing to learn about hydraulics and pneumatics. The reason is the electronic devices divert your attention and also cause strains while reading eBooks. In he began specializing in sequence and closed loop control systems using Programmable Controllers PLCs with hydraulic and pneumatic actuators. He has written fifteen books on electronics and process control including Logic Designers Handbook, Industrial Control Handbook, Programmable Controllers, Control Engineering, along with many amateur- level books, among them Introduction to Operational Amplifiers.
Pneumatic systems used in industry are commonly powered by compressed air or compressed inert gases. A centrally located and electrically-powered compressor powers cylinders , air motors , pneumatic actuators , and other pneumatic devices. A pneumatic system controlled through manual or automatic solenoid valves is selected when it provides a lower cost, more flexible, or safer alternative to electric motors and hydraulic actuators. Pneumatics also has applications in dentistry , construction , mining , and other areas. Pneumatic systems in fixed installations, such as factories, use compressed air because a sustainable supply can be made by compressing atmospheric air. The air usually has moisture removed, and a small quantity of oil is added at the compressor to prevent corrosion and lubricate mechanical components. Factory-plumbed pneumatic-power users need not worry about poisonous leakage, as the gas is usually just air.
Practically every industrial process requires objects to be moved, manipulated or be tronics and process control. This book has been written by a process control engineer as a guide to the operation of hydraulic and pneumatics systems. It is.
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Hydraulic and pneumatic systems books Pneumatics and control system development the product development in pneumatics can be considered in a hydraulic and pneumatic systems books number of areas: actuators sensors and input devices processors accessories control systems the following factors must be taken into account in the development of pneumatic control systems.
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Practically every industrial process requires objects to be moved, manipulated, or be subjected to some form of force. This is generally accomplished by means of electrical equipment such as motors or solenoids , or via devices driven by air pneumatics or liquids hydraulics. Traditionally, pneumatics and hydraulics are thought to be a mechanical engineer's subject and are generally taught as such in colleges. In practice, techniques and, more important, the faultfinding methodology tend to be more akin to the ideas used in electronics and process control. This book has been written by a process control engineer as a guide to the operation of hydraulic and pneumatic systems. It is intended for engineers and technicians who wish to have an insight into the components and operation of a pneumatic or hydraulic system.
Hydraulics and Pneumatics: A Technician's and Engineer's Guide serves as a guide to the hydraulic and pneumatic systems operations.
He has written fifteen books on electronics and process control including Logic Designers Handbook, Industrial Control Handbook, Programmable Controllers.Reply