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