Which of the following compressors does not require lubrication?

The rotary lobe type compressor is designed in such a way that it operates without the need for lubrication in the compression chamber. This is achieved because the working parts are kept separated by the geometry of the lobes, which creates a slight gap between them, effectively minimizing friction and wear. As a result, a rotary lobe compressor can function efficiently in applications where oil-free operation is necessary, such as in certain industrial processes and applications.

In contrast, the other types of compressors mentioned commonly require lubrication to reduce friction between moving parts, maintain operational efficiency, and ensure longevity of the components. For example, rotary screw compressors use oil for lubrication and sealing purposes, while sliding vane compressors also rely on lubrication within their operation to function properly. The axial flow type generally has components that require lubrication as well to mitigate wear and tear.