{HEAD ~ A pressure} of at least 20 psi may be maintained within {TAIL ~ the chamber} 10 
maintained within
{ HEAD ~ A pressure } of at least 20 psi may be maintained within { TAIL ~ the chamber } 10
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH