Control valves are located at the inlet ports to control the supply of chemical concentrates into the manifold, and {HEAD ~ the concentrates} are drawn into the manifold by {TAIL ~ the operation} of a positive displacement pump 
are drawn by
Control valves are located at the inlet ports to control the supply of chemical concentrates into the manifold , and { HEAD ~ the concentrates } are drawn into the manifold by { TAIL ~ the operation } of a positive displacement pump
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH