When the pump starts, the flow through {TAIL ~ the part} 7 of {HEAD ~ the mixing valve} begins and obtains the mixing within the pump station 
When the pump starts , the flow through { TAIL ~ the part } 7 of { HEAD ~ the mixing valve } begins and obtains the mixing within the pump station
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH