{HEAD ~ All the intermediate positions} between these two end positions blocking {TAIL ~ the orifices} 7 allow the loss of head to be adjusted partially as required 
{ HEAD ~ All the intermediate positions } between these two end positions blocking { TAIL ~ the orifices } 7 allow the loss of head to be adjusted partially as required
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH