Lubricated Compressors:
Generally big reciprocating compressor cylinders are lubricated to avoid wear and tear of liner, piston rings, rider rings and stuffing box. Lubricants are injected in drops and are lost with the process gas.
Lubrication of cylinder reduces wear of parts, enhances life of parts and also reduces gas discharge temperature. It is necessary for the lubricant to be compatible with the process gas and down stream system. Generally recip compressors above 100 KW are lubricated type.
Lubrication of cylinder reduces wear of parts, enhances life of parts and also reduces gas discharge temperature. It is necessary for the lubricant to be compatible with the process gas and down stream system. Generally recip compressors above 100 KW are lubricated type.
Non-Lubricated Type:
There are many services in which oil in any form in the compressed gas, is not acceptable such as instrument air compressor and some process gas compressors. In such services oil is not injected in the cylinders, instead wear parts are made of soft material with low co-efficient of friction such as PTFE, CFT etc. The wear rate of stuffing box packing, rider rings piston rings and cylinder/liner surface may be comparatively more.
Process requirements and gas to be compressed dictate whether to use a compressor with lubricated or non-lubricated cylinder. Some chemical processes do not permit use of lubricant in the system, due to quality problems, catalystpoising etc.
Following factors must be considered,
1. Non-lubricated compressors cost more than lubricated compressors
2. Non-lubricated compressors require more power
3. Non-lubricated compressors require more maintenance, labyrinth compressors being exception.
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