For the interstage and final cooling in piston, compressors have to fulfill specific requirements. 
The most important type for low and middle pressure range are the tube bundle coolers.
It consists of a cylindrical outer tube (1), closed on its end by covers (8) and the bundle of tubes (3) , which in turn is usually closed on its ends by two flat plates (2). For bundles of tubes fastened on both ends special constructions are necessary to avoid buckling reduce bending ( for example a design to provide compensation for the elongation of the tubes, an axially movable cover (floating cover) or U-tubes with only one cover plate). Normally the coolant is led through the tubes and the gas, diverted by baffles, flows in the opposite and cross direction of the coolant flow. [13 – 15]
In the low pressure range, also aircooled tube coolers are being used. The tubes are close to each other and are fitted with cooling fins.
In the high pressure range double tube coolers, with the gas flowing through the inner tube, are the preferential design. A simple design is the snake tube cooler, where the gas is led through a snake tube (sometimes also in parallel for several stages) through the hardly moving cooling liquid. It is mainly used for small volume flows and high pressures.
The calculation of the cooler starts with the following correlation between the main parameters :
For the heat flux the compression work done in a stage represents the upper limit.
For approximations values from practical experience for the coefficient of thermal conductivity can be used. The diagram as shown is based on the assumption, that the heat flow is mainly dependent on the heat transfer on the gas side. This heat transfer can be calculated for all types of coolers (1, 2 tube bundle -, 3 tube, 4 double tube, 5 snake tube coolers) approximately as a function of the product of gas velocity cG and pressure pG.
The mean logarithmic temperature difference between gas and coolant at equal inlet temperatures will be the lower, the closer the gas outlet temperature is to the coolant inlet temperature.