Air compressors are categorized into two main types based on the presence of oil in the produced air.
- Oil-Flooded Compressor:
An oil-flooded air compressor releases air that contains oil. In the case of HITACHI brand, this type is referred to as the OSP (Oil Inject Screw) package. The OSP compressor includes oil in the air it generates. During the compression process, this compressor still employs oil between the male and female screw rotors. This lubricating oil also serves as a bearing lubricant. OSP compressors are commonly used in industrial applications such as pneumatic engine propulsion, press machine operation, and cleaning purposes. - Oil-Free Compressor:
An oil-free air compressor produces air that is free from oil content. For HITACHI brand, this falls under the DSP (Dry Screw Package) type or SDS (Super Dry Screw Package). This type of compressor ensures that no oil is used in the air end during the compression process. Unlike the oil-injected type where the male and female rotor surfaces touch, in the oil-free version they remain separate. Although this compressor requires lubrication, the lubricating oil is kept separate from the compression process. Since there is no oil in the AIR END, the resulting air is oil-free. Typically, this kind of compressor finds use in industries like food and pharmaceutical production. The food and drug sectors specifically demand the DSP or SDS compressor types to prevent oil contamination in the final products.
