WL series of standing reciprocating vacuum pumps are the renewed products based on the primeval W series of lying ones.Compared with the W series of ones, they have the specialty as follows: 1) The gas valves are installed on the cover and neck of the cylinder(the W series ones are on the body of the cylinders),so it can increase the area of cooling water.The process of compressing gas is approximately isothermal,so it can decrease the loss of power and can save energy by 10%~15%.The area it holds can decrease by 1/2. 2) The piston of the lying reciprocating vacuum pump will go down because of the weight of itself ,so it will be worn away unsymmetrically. The WL series of ones improved this shortcoming,it can decrease the wearing away of the moving units as piston and connecting pole; 3) We can serve the no-oil WL series of standing reciprocating pumps.