At the input and output of a material from the dryer 15 drum feeders 18 are installed, playing a role not only as batch feeders, but also as {HEAD ~ gas sealers}, not permitting {TAIL ~ any external air intake} 
not permitting
At the input and output of a material from the dryer 15 drum feeders 18 are installed , playing a role not only as batch feeders , but also as { HEAD ~ gas sealers } , not permitting { TAIL ~ any external air intake }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL