Conversion of large ammonia refrigeration compressors to run without lubrication

The article describes the conversion of lur^t ammonia compressors AO-600 and AKG-56» lubrication-free operation. Design of pistons has been changed for this purpose: steel welded and cast aluminium pistons of lightweight construction have been developed. A procedure for putting of supporting-guide rings from the materials AFC 80BC and F4K20 on a piston has been developed. Comparative tests of seals and supporting rings from these materials have been carried out. Asa result of the investigations large ammonia refrigerating compressors AO-1200 217 without lubrication of cylinders and glands have been developed and their commercial production was started.