Throttle units are built into the suction line of hydraulic pumps and compressors to specifically influence the filling of pumps or the compression pressure in the case of compressors. The suction throttle units are passed through due to the difference between the ambient pressure and negative pressure (suction pressure).
The suction orifice, the overlap/underlap conditions, the pressure difference and the temperature and type of the medium all influence the delivery characteristic of a suction throttle pump. Suction orifices with adjustable cross sections are used to regulate the suction throttle. In the case of compressors, the built-in throttle unit is controlled by the compression pressure, closing when the maximum value is exceeded and opening when the pressure falls below the minimum value.