691 – Corken D-Style Vertical Compressor (691 and 891)
D-style vertical compressors utilize two sets of V-ring packing per piston rod and one (single) distance piece
The lower packing set has an adjustable packing screw used to maintain the sealing performance over the life of the packing.

With the exception of models D791 and D891, all D-Style compressors deliver oil-free gas compression
Typically used in toxic and corrosive applications where oil-free gas is required and leakage containment is desirable.