Pneumatics And Hydraulics - PDF

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Application Of Pneumatics And Hydraulics1APPLICATION OF PNEUMATICS AND HYDRAULICSBy NameCourseInstructorInstitutionLocationDate
Application Of Pneumatics And Hydraulics21. Using the nomogram and charts (FIGURES 1 and 2) on pages 4 and 5, determine the diameterof a suitable air main for the distribution of 6 m3 min–1 FAD. System pressure is 6 bar, thelength of the pipe run is 175 metres, and a maximum pressure drop of 0.3 bar is allowed.The distribution main must also include the following:• 4 bends (r = 2d)• 2 elbow fittings• 6 tee connectors• 2 diaphragm valves.Solution.Pipe flow, Q = 6m3/minQ = 6 × 1000/60Q = 100dm3/sLet the initial diameter of the pipe be dmmWe, therefore, assume that the initial velocity is 15m/sAir density at 6 bar = 1.225 × 6= 7.36kg/m3The initial area, A = Q/60/15= 0.006667m2Initial diameter, d = (4 × A/π)0.5
Application Of Pneumatics And Hydraulics3= 0.092m= say 100mmThe total equivalent length LT= Lpipe+ Lbends+ Ltee+ Lelbow+ LdiaphragmLT= 175 + (4 × 0.8) + (2 × 7) + (6 × 10) + (2 × 6)LT= 264.2mFrom the nomogram (refer image) we get 2.2mbar/m pressure drop. Hence, total pressure drop is2.2 × 10-3×264.2 = 0.58bar > 0.3barHence we need to go for 150mm diameter pipe which is beyond the nomogram.2. Describe the relevant advantages and disadvantages of using steel, copper or plastic pipe for adistribution main.Solution.Steel pipesSteel pipes are available in various types depending on the percentage of carbon present.Advantages.High resistance to abrasionHighly durable and practically indestructible, providing a long lifespanThere are minimal noise and vibration between the fittingsCheaper and easier to install in comparison to other materials due to convenient lengths
Application Of Pneumatics And Hydraulics4Disadvantages.They are heavy and require special means of transportThey not advisable to use in areas that are inaccessibleDue to heavyweight, these pipes are usually shorter in lengths thus leading to many joints(De Volder and Reynaerts, 2010).They are prone to corrosion due to rustingCopper pipesAdvantagesThey are easy to installThey are more flexible than most of the other materialsThey are more resistant to natural forces and disastersThey have a high resale valueThey have high fire resistant properties/qualities.DisadvantagesHigh acquisition and installation costsIt is prone to corrosion in acidic conditionsThey cannot handle extreme temperatures. This is because the pipes crack when heatedand bursts when exposed to a lot of colds.The water gets a metallic taste due to mild reaction to the copperDue to high thermal conductivity thorough lagging is needed (De Volder and Reynaerts,2010).Due to good electrical conductivity, the pipe should be grounded to avoid short-circuiting
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