Piston (reciprocating) compressor

The sourcebook (third edition) separates single-acting compressors, in which compression takes place on the top side of the piston, from double-acting ones, which use both sides of the piston. For single-acting designs it describes lubricated versions with compression and lubricant-control piston rings, lubricant-free designs that keep lubricant out of the compression chamber, and lubricant-less, or oil-less, designs that also have no lubricant in the crankcase.

NHS England guidance, HTM 02-01 (2026), lists reciprocating compressors among the most common types for medical air and says they may be of the oil-lubricated, carbon-ring, PTFE-ring or diaphragm-sealed type. Because PTFE rings and lubricating oils could decompose at high temperatures to form toxic products, it says this can be countered by a temperature sensor on the cylinder head or compressor output, with controls that cut off the power if excessive temperatures are sensed.

ULTRACECO ESW is the Ultra Controlo oil-free piston compressor range, with QuAir 3 touch-screen controllers, a first maintenance at 10,000 hours and a belt that can be changed in 5 minutes without disassembling the compressor. ULTRAAR ESW medical air plants use these oil-less piston compressors and are designed with 1 to 8 compressors, among other configurations.