Using a positive displacement gas compressor to raise the pressure of a gas stream will often generate pressure pulsations at the suction and discharge connections of the machine being used. If these pressure pulsations are of a high level and are allowed to enter the connected pipework, then it is possible for that pipework to start vibrating, which if the vibration is severe can result in mechanical failure of the pipe materials.
Guidance on the allowable pressure pulsation levels is given in API618 together with the requirements for theoretical analysis.

A positive displacement gas compressor will usually be a reciprocating gas compressor with one, or more plungers, or a rotary lobed blower with two, or more, lobes on each rotor.

For a reciprocating compressor each downward stroke of each plunger will generate a pressure pulsation in the suction pipework as the valve that admits the gas to the plunger first opens, then closes. On the return stroke the plunger will force the gas out through the discharge valve into the discharge pipework, again causing pressure pulsations, but this time in the discharge pipe, as the discharge valve for the plunger opens, then closes. 

[suction dampener] For a rotary compressor, such as a "roots blower", the internal rotors are shaped in a way that creates intermeshing lobes, with each rotor typically having two or three lobes.
As these shaped rotors rotate the lobes create a cavity that progresses, from suction side to discharge side, around the outside of the rotor, each time a lobe passes a port, either suction or discharge, a pressure pulse is created on that side of the machine.

To alleviate these pressure pulsations a gas pulsation dampener may be fitted to either the suction or discharge port of the compressor.

The gas pulsation dampener comprises either a single or multiple volume connected with tubes and/or orifices sized to attenuate the pressure pulses.