ASME EA-2G:2010 pdf free download

ASME EA-2G:2010 pdf free download.Guidance for ASME EA-2, Energy Assessment for Pumping Systems.
Pump speed control includes both mechanical and electrical methods of matching the speed of the pump to the flow/pressuw demands of the system. VSDs, multiple-speed pumps. and multiple pump ctmIigurations are usually the most efficient flow control options, espedaily in systems that are dominated by friction head. because the amount of fluid energy added by the pumps is determined directly from the system demand. Pump speed control is especially appropriate for systems in which friction head predominates.
Both VSDs and multiple-speed motors provide clii- dent system operation by driving pumps at different speeds according to system needs. During a period of low system demand, the pump is operated at low speeds. The primary functional difference between VS[> and multiple-speed motors is the degree of speed control available. VSDs typically modify the speed of a single- speed motor through mechanical or electrical methods. while multiple-speed motors contain a different set of windings for each speed. VSDs are practical for applications in which flow demands change continuously. For more information on variable speed pumping., we references 131 and 1161 in Nonmandator Appendix A.
Multiple pump arrangements typically consist of pumps placed in parallel in one of two basic configurations: a large pump/small pump configuration, or a series of identical pumps placed in parallel. In the large pump/small pump case, the small pump. often called the “pony pump.’ operates during normal conditions. The large pump is used during periods of high demand. Because the pony pump Is sized for normal system operation, this configuration operates more efficiently than a system that relies on the large pump to handle loads far below its optimum capacity For more inlormaLion on this type of pumping system configuration, see reference 131 in Nonmandatnrv Appendix A.
With a series of identical pumps placed in parallel, the number of operating pumps can be changed according to system demands, Because the pumps are the same size they can operate together, serving the same discharge header. If the pumps were different sizes, the larger pumps could dominate the smaller pumps and could cause them to operate less efficiently unless care is taken when programming the system operating scheme. If the proper pumps ale selected, each pump can operate closer to its best efficiency point. An added flow control benefit of parallel pumps is that a system curve remains the same whether one or several pumps are operating; what changes Is the operating point along this system curve. In Systems dominated by friction, parallel pump configurations should be avoided, since the operating point for each pump will move up its curve as more pumps are started, which in turn will lead to inefficient operation of all the pumps.
Multiple pumps in parallel are, however, well suited for static head-dominated systems where starting or stopping additional pumps will not significantly affect.