Copyright Goodheart-Willcox Co., Inc. Chapter 16 Conditioning and Distribution of Compressed Air 405 on the fact that a distribution system serves multiple workstations. In addition, each of these workstations contains actuators that intermittently operate under varying loads. These multiple variables make appli- cation of a simple formula for pipe sizing impracti- cal. The solution recommended by many experienced pneumatic system staff is to design new systems based on information from similar, proven, existing systems. This process begins by calculating the total air con- sumption of the actuators planned for the new system. Individual consumption data are available from man- ufacturer literature or engineering data handbooks. System air consumption can be determined by totaling the air consumption for each actuator to be included in the system. This fi gure will be greater than the actual volume of air used by the operating system, as few of the system actuators operate on a continuous basis or at full load, Figure 16-12. In most systems, the actual amount of air needed is considerably less than the combined consumption fi gure. Next, multiply the estimated air consumption by two additional factors. First, multiply by a time factor that is the percentage of time actuators function during Distribution of air from portable compressors typically involves fl exible hoses, Figure 16-11. At some construction sites where work will last for extended periods, pipe main lines may be installed. Hoses, like the pipes of fi xed systems, must be sized to provide air with minimal pressure drop. Care must be taken to protect the hose from cuts and abrasions. The lines should be kept straight and free from excessive kinks, although this is diffi cult in a work situation. Pressure drops in a twisted hose are as real as any pressure drop caused by excessive fi ttings in a fi xed distribution system. 16.2.2 Sizing of Distribution System Lines The size of the pipe used in the distribution system should be based on the air needed by system actua- tors. However, determining this volume of air becomes a problem as consumption varies considerably during the operation of most systems. This variation is based DeVilbiss Air Power Company Figure 16-11. Distribution lines for air delivered by portable compressors are typically hose. Care must be taken to provide a system with minimal pressure drop by minimizing hose length and the number of fittings and eliminating bends or kinks. DeVilbiss Air Power Company Figure 16-12. Estimating air consumption for use in sizing distribution lines for a new system is difficult, as actuator operating times and load factors vary. This is emphasized by the many variables at typical workstations.