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The WLW Series is Zhongtian's oil-free vertical reciprocating vacuum pump range, designed for industrial process applications where contamination of the pumped gas by cylinder lubricating oil must be avoided. The vertical reciprocating design separates the gas-contacting pumping cylinder from the lubricated mechanical drive section. Self-lubricating piston-ring materials allow the pumping cylinder to operate without oil lubrication, making the series particularly suitable for process-gas recovery, solvent recovery and contamination-sensitive industrial vacuum applications. With pumping speeds from 50 to 1000 L/s (180 to 3600 m³/h) and an ultimate pressure of 2000 Pa, the WLW Series covers a broad range of chemical, pharmaceutical, drying, recovery and environmental process-vacuum requirements.
Working Principle
The WLW Series operates on the reciprocating positive-displacement principle. An electric motor drives the crankshaft through the transmission system. The crankshaft, connecting rod and crosshead convert rotary motion into the vertical reciprocating motion of the piston. As the piston moves inside the cylinder, the cylinder volume changes periodically. During the suction stroke, the increasing chamber volume reduces the pressure inside the cylinder and opens the inlet valve, drawing process gas into the pump. During the discharge stroke, the decreasing chamber volume compresses the gas. When the cylinder pressure exceeds the discharge-side pressure, the discharge valve opens and the gas is expelled from the pump. The gas-contacting cylinder uses self-lubricating piston-ring materials, allowing the pumping chamber to operate without oil lubrication.
Key Features
Oil-Free Pumping Cylinder
The gas-contacting pumping cylinder operates without oil lubrication. Self-lubricating piston-ring materials are used to reduce friction while avoiding contamination of the process gas by cylinder lubricating oil. This design is particularly valuable in applications involving product recovery, solvent recovery and processes where oil contamination of the pumped gas is undesirable.
Vertical Reciprocating Design
The vertical arrangement places the reciprocating pumping cylinder above the mechanical drive section, providing a compact industrial footprint and separating the gas-contacting pumping components from the lubricated transmission mechanism. The crankshaft, connecting rod and crosshead provide the mechanical motion required to drive the piston through the suction and discharge cycles.
Process Gas Recovery
Because the gas-contacting pumping cylinder operates without oil lubrication, the WLW Series helps avoid contamination of the discharged process gas by cylinder lubricating oil. This makes the pump particularly suitable for processes involving valuable-gas recovery, solvent recovery and downstream condensation or treatment.
Corrosion-Resistant Options (WLW/F)
Corrosion-resistant WLW configurations are available for compatible chemical and process applications. Alternative wetted-part materials can be selected according to the pumped medium, concentration, temperature and process conditions. Material suitability for specific media must be confirmed separately.
Operating Media
The WLW Series is primarily intended for pumping clean, dry and compatible non-corrosive gases. For applications involving condensable vapours, solvents, corrosive or hazardous media, operating conditions and material compatibility must be confirmed separately.
*Ultimate pressure measured without gas ballast, with air at 20°C.
*Pump Speed refers to the pump crankshaft speed.
*Pumping speed shown in L/s with m³/h equivalent (L/s × 3.6).
Typical Applications
Vacuum distillation, evaporation, crystallization and compatible process vacuum
Oil-contamination-sensitive vacuum drying, concentration and process applications
Vacuum processes requiring recovery and downstream condensation of compatible solvents
Industrial drying applications requiring an oil-free gas-contacting pumping chamber
Recovery and downstream treatment of valuable or reusable process gases
Vacuum-assisted gas collection, condensation and recovery processes