The vent hole is preferably closed between {HEAD ~ the tapping} of {TAIL ~ the intermediate pressure portion} and the discharge pressure portion 
The vent hole is preferably closed between { HEAD ~ the tapping } of { TAIL ~ the intermediate pressure portion } and the discharge pressure portion
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH