Fluid Mechanics of Mechanical Systems: Design of Real Piping Systems - Assignment Example

Surname: Presented to Institution Name, Location Date Fluid Mechanics of Mechanical Systems (Dеsign оf Rеаl Рiрing Systеms) The real piping process involves the development of design criteria mainly for the real piping system. For a proper real design criterion, it is important that the client and the given contractor get into an agreement on the basis of the design, the process and finally the mechanical and electrical components of the system. In the simplest case ever, any failure of the structures when piping is done is caused by either stress or strain when components reach their critical value. To avoid damages and losses that are caused by stresses and strains it is important that the material used for the piping be considered (FAY, 1994). There exist a good number of materials that can be in the design of real piping systems which include plastics that include the renowned PVC’s and metals such as copper. To estimate the chances of failure of structural materials it is important that we calculate the stress and the strains that will be enough to withstand the given load. Engineers have to know the critical points of pressure exerted due to both stress and strain that will cause failure on the structural materials. These points will enable the engineers to know what material he should use in the design of the piping system. Copper pipes and fittings have proven to produce remarkable results in the design of piping systems. Copper has been used for over 75 years in the transportation of fluids since the time of the ancient Egyptians. The reason copper is used mostly is due to the existance of the majority of the problems that arise when using copper piping can be evaded by using proper design and installation processes. The major causes of difficulty are mainly erosion and other mechanically induced failures. Using an undersized system of piping or a bigger recirculation pump causes a very high water velocity. One should consider installing of pumps with a smaller capacity or a throttling bypass on a pump that is already installed to help in the lowering of the velocity of water within the system. The velocity of water that is recommended is a copper piping system is about 5-8 feet per second for the cold water system and 4-5 feet per second for the hot water system that is less than 140 degrees Fahrenheit and finally about 2-3 fps for a hot water system with a temperature that is higher than 140 degree Fahrenheit. It is also important to consider the chances that numerous and sudden changes in the direction of the piping system may occur, and these are created by the structural conditions. The conditions include long radius or diameter. Good fittings have to be used in order to minimize the problems caused by the laminar flow. When there are excessive amounts of dissolved gases suspended particles or vapor, there is a high chance that they will cause corrosion. To avoid corrosion, there should be high velocity on the system in order to entrain the air. Selecting a pump The pressure that is produced by vapor in mainly dependent on the temperature of the fluid, in this project I have chosen centrifugal pumps that are highly vulnerable mainly when pumping solutions with high temperatures. Cavitation highly affects centrifugal pumps especially when pumping high-pressure fluids and a careful design have to be used if a centrifugal pump has to be used in pumping high-temperature fluids. The effects of cavitations cannot be underestimated; the violent collapse of the cavitations produces a shock wave that can easily curve materials mainly from the internal components of the pump. This usually affects the leading edge of the impeller; this creates much noises mostly described as the pumping gravel. In addition, the unavoidable increase in the vibration can easily lead to other mechanical faults within the pump and the equipment associated. The pump operates just like many other pumps. Fluids flow from regions of high pressure to regions of low pressure CALERO, J. S. (2007), The pumps operate by creating regions of low pressure at the inside of the pump; this allows the fluid to flow from the outside under atmospheric pressure. Placing a pump under at the top of the mercury barometer, even with a perfect vacuum mainly at the inlet of the pump, the atmospheric pressure will automatically affect how high the pump will lift the fluid. With the liquids that are lighter than mercury, the height of the lift will increase, but at the same moment the physical limit to the operation of the pump basing on the pressure of the external pump. This particular limit is a major consideration when looking into the Net Positive Suction Head. The Net Positive Suction Head available refers to the absolute pressure exerted at the suction port of the pump, while the Net Positive Suction head refers to the minimum amount of pressure needed at the port of the pump, it is meant to keeping the pump from cavitations. The NPSH available has to be calculated, but the NPSH required must be given by the pump provider as it is the function of the pump. NPSH available should always be greater than the NPSH required in order for the pump to operate without experiencing cavitations. In order to comprehend cavitations, one must understand very well the issue of vapor pressure. Vapor pressure refers to the pressure that is needed to boil a liquid at a given temperature. One of the best examples of high vapor pressure liquids is the soda water. Even at a room temperature the air that is carbon dioxide fixed in the soda is let out, in a container that is closed, the soda will be pressured and the vapor will remain entrained. The temperature of the fluid has effect on vapor pressure CALERO, J. S. (2007) A cold soda bottle will always have a small pressure as compared with a warm one. Water is another perfect example; it will not boil at the room temperature since the vapor pressure is lower as compared to the surrounding pressure of the atmosphere. However, when the temperature of water is raised to 212 degrees Fahrenheit, the water vapor is let out because at that temperature the pressure of the vapor is greater than the atmospheric pressure. Cavitations of the pump take place when the pressure of the pump inlet comes down as compared to the vapor pressure of the liquid. The vapor bubbles that form at the inlet of the pump and is moved to discharge of the pump at the point where they collapse. They often take small pieces of the pump with them. Cavitations are always characterized by loud noises, loss of capacity and damage on the material. References KAMBE, T. (2007). Elementary fluid mechanics. New Jersey [u.a.], World Scientific. CALERO, J. S. (2007). The genesis of fluid mechanics, 1640-1780. Dordrecht, the Netherlands, Springer. http://www.myilibrary.com?id=123946. FAY, J. A. (1994). Introduction to fluid mechanics. Cambridge, Mass [u.a.], MIT Press. KUNDU, P. K., & COHEN, I. M. (2007). Fluid Mechanics. Burlington, Elsevier. http://www.123library.org/book_details/?id=113752. LANDAU, L. D., & LIFSHIT︠S︡, E. M. (1959). Fluid mechanics. London, Pergamon Press DOUGLAS, J. F., GASIOREK, J. M., & SWAFFIELD, J. A. (1995). Fluid mechanics. Harlow, Essex, England, Longman Scientific & Technical. Read More