In the open position which is shown, {HEAD ~ air} can flow through the ventilation opening 14 in the housing 12 past {TAIL ~ the closing part} 16 between the covers 21 and the latching means 18, 19 
flow past
In the open position which is shown , { HEAD ~ air } can flow through the ventilation opening 14 in the housing 12 past { TAIL ~ the closing part } 16 between the covers 21 and the latching means 18 , 19
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH REL OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH