filter regulator means for filtering {HEAD ~ the air} entering the signal air path and for regulating the pressure in {TAIL ~ the signal air path} to a predetermined pressure 
filter regulator means for filtering { HEAD ~ the air } entering the signal air path and for regulating the pressure in { TAIL ~ the signal air path } to a predetermined pressure
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH