WLW-B free pump is oil-free vacuum pump WLW the most significant improvements made by a new generation of vacuum pump, which pumps the cylinder crankcase body parts and components completely isolated, completely solved the work process has been liquefied gas cylinder inside the media leaks to which the crankcase oil, while avoiding a string of oil inside the crankcase into the cylinder components, and thus no real solution to the pump by pumping the gas to be recovered by pumping the gas to the crankcase oil with reaction problems encountered, organic solvents, low molecular weight polymer, liquid vapor, corrosive gases, vacuum suction weak with very prominent advantages. Is the W-type horizontal vacuum pump, water jet pumps, water ring pumps ideal alternative.