{HEAD ~ The valve element} also has {TAIL ~ a through passage} 23 which, when arranged in an open position as shown in FIG 1, enables passage of gas through the valve 
has
{ HEAD ~ The valve element } also has { TAIL ~ a through passage } 23 which , when arranged in an open position as shown in FIG 1 , enables passage of gas through the valve
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH