The valve is closed by swinging the valve element through 90 degrees thus moving the valve element passage out of registry with {HEAD ~ the ports} 13 13 of {TAIL ~ the chamber} 
The valve is closed by swinging the valve element through 90 degrees thus moving the valve element passage out of registry with { HEAD ~ the ports } 13 13 of { TAIL ~ the chamber }
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 OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL