CASE HISTORIES OF ON-LINE AND OFF-LINE CLEANING OF HVAC PIPING SYSTEMS

摘要

The cleaning of HVAC and industrial cooling systems is a complex process that requires careful planning. The presence of large quantities of deposits in pipes and equipment, or the appearance of leaks, is usually the driving force for considering a cleaning program. However, the choice between cleaning and pipe replacement, the further choice between online and off-line cleaning, and the selection of the specific cleaning program to be used, all depend upon detailed knowledge of the systems involved. Some of the factors that must be considered include: deposit composition; the condition of the pipes to be cleaned; and the design of the system, including circulation patterns, flow rates, metallurgy, etc. Also important are the possibilities for removing suspended solids from the circulating water and for isolating equipment to be cleaned; the water treatment history of the system; and system operational requirements. These can include, for example, a need to maintain continuous system operations while cleaning, or to provide specific "windows of time" during which the system can be off-line. Other factors specific to individual systems can also be critically important. Methods for evaluating the progress of the cleaning process and for determining when cleaning is complete must also be carefully planned. This paper examines several detailed case histories of on-line and off-line cleaning of condenser water systems. The amount of advance preparation, the selection of the cleaning method, the specific chemical program, and the degree of performance monitoring are all shown to critically affect the success of the program.