Which two types of pistons are commonly used in air compressors?

The two types of pistons commonly used in air compressors are rotary and reciprocating.

Rotary pistons are designed to provide continuous airflow by rotating around a central axis, making them suitable for applications requiring a steady supply of compressed air. They tend to be more efficient for larger volumes of air and operate smoothly with less noise. On the other hand, reciprocating pistons use a back-and-forth motion to compress air, which is typical in many smaller or portable air compressors. These are often used in situations where high pressure is needed but with a lower volume of air output.

The other options listed do not correspond to widely recognized categories of pistons in the context of air compressors. While differential and trunk pistons may be valid in different mechanical applications, they are not standard classifications for air compressor pistons. Standard and high-pressure also refer more to specifications of air compressors rather than distinct piston types. Thus, the most recognized and practical classifications in the context of air compressors are rotary and reciprocating pistons.