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11-3 SINGLE-PASS (INTERMITTENT) PACKED-BED FILTERS 731 <br /> Meters and counters included in a typical control panel include: an elapsed time <br /> meter for the septic tank pump, an, elapsed time meter for the filter pump, a dose <br /> counter, and an override counter. The elapsed time meters are used to record the <br /> total time the effluent and filter pumps have been running. The dose counter is used <br /> to record the number of doses that have been applied to the filter.The override counter <br /> is used to record the number of times the pump had to be turned on to accommodate <br />' flows in excess of the normal daily flow. Additional details on pumps and controls <br /> may be found in Bounds (1996). <br /> System Hydraulics for Intermittent Filters ► : <br /> The hydraulic analysis for an intermittent packed-bed filter involves determination <br /> of the system head capacity curve for the given system configuration so that a proper . <br /> pump can be selected and the difference in discharge between orifices can be deter- <br /> mined. <br /> etermined. <br /> G System head discharge curve. The elements that must be considered in <br /> the development of the system`head discharge curve are summarized below, and <br /> identified graphically in Fig. 11-14. <br /> Hydraulic grade tine(HGL) <br /> l Minor headloss through f <br /> Headloss <br /> pump discharge,h,,,d <br /> through Headloss through <br /> manifold,him transport pipe,hP <br /> Headloss <br /> through <br /> lateral,he <br /> Residual <br /> head,h,, Orifice <br /> Distribution laterals <br /> Total <br /> dynamic ~-- Distribution manifold <br /> head,TDH <br /> Pipeline from septic <br /> tank to filter <br /> Static head,h$ <br /> Liquid level <br /> Pump in filter vault <br /> Septic tank <br /> FIGURE 11-14 <br /> Definition sketch for the energy gradient in an intermittent <br /> sand filter system. <br /> i <br />