Abstract
This paper presents a survey of problems common to all reciprocating piston compressors for oil-free delivery of gas, and states typical problems associated with labyrinth piston compressors. The paper discusses special arrangements for placing guiding elements outside the process gas area; the development of a self-centring, contact-free piston; and design and material problems relating to a labyrinth piston-rod gland. The closed, pressurized crankcase designs make it possible to use contactless sealing techniques in refrigerating and many other process gas applications with oil-free delivery or recycling of gas. Mention is made of gas in the crankcase and associated problems, such as oil-gas dilution and inside-pressure in the frame. The paper also presents an efficiency comparison between contactless and ring-sealed piston compressors and briefly mentions the reliability of labyrinth pistons, giving statistics on the sequence of replacement.
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