SL + Series high-efficiency low-pressure screw air compressor uses a host specially developed for low-pressure applications. The rotor clearance and the main engine shell are precisely designed, which not only changes the exhaust source port and increases the bearing seat, but also all the designs of the main engine meet the requirements of large flow and low pressure. With relatively small energy consumption, low-pressure compressed air with appropriate pressure is directly output to achieve the required exhaust volume and save energy by more than 25%. When the system operates under low pressure, the pressure and thermal load of parts are reduced, which makes the compressor run more stably and have a longer service life.