LDJ plunger metering pump is a reciprocating positive-displacement pump designed for accurate dosing, controlled feeding and high-pressure injection of industrial liquids. During operation, the plunger moves back and forth inside the liquid end, drawing the process medium into the pump head and discharging a measured volume into the downstream system.
 

Because both the plunger and the packing seal come into direct contact with the pumped medium, selecting suitable plunger materials, seals, valves and wetted components is essential for reliable operation. Stainless steel plungers are available for general industrial fluids, while oxidized ceramic plungers provide excellent corrosion resistance, high surface hardness and improved wear resistance.

The compact plunger pump head offers good self-priming performance, limited internal dead space and dependable metering accuracy. Automatic lateral alignment between the plunger and seal helps reduce uneven friction, minimize component wear and extend the service life of the packing system.
 

Different liquid-end configurations are available to meet varying pressure, temperature, viscosity and chemical-compatibility requirements. Optional designs include heating or cooling jackets, seal-flushing structures, specially engineered packing seals, integrated insulation jackets and easily removable inlet and outlet valve assemblies.

With a broad range of flow and pressure combinations, the LDJ plunger metering pump can be used in petroleum, petrochemical, chemical production, environmental protection, power generation, pharmaceutical processing, pulp and paper, food processing and other industrial applications requiring controlled liquid delivery.




Working Principle of LDJ Plunger Metering Pump for High-Pressure Chemical Dosing and Injection:
The plunger metering pump uses the reciprocating movement of a plunger to change the volume inside the pump head. During the suction stroke, the inlet valve opens and the process liquid enters the liquid chamber. During the discharge stroke, the inlet valve closes, the outlet valve opens and the liquid is delivered into the process pipeline.

Since the plunger and packing seal directly contact the pumped medium, the liquid-end material and sealing system must be selected according to the liquid’s corrosiveness, abrasiveness, viscosity, temperature and operating pressure.

• Reciprocating positive-displacement metering principle
• Accurate and repeatable liquid delivery
• Suitable for high-pressure chemical dosing
• Wide selection of flow and pressure combinations
• Steady-state metering accuracy up to ±1%
• Good self-priming capability
• Compact liquid end with limited dead volume
• Stainless steel plunger available
• Corrosion-resistant ceramic plunger available
• Ceramic plunger offers high hardness and wear resistance
• Automatic lateral alignment between plunger and seal
• Reduced uneven wear on packing components
• Customized packing and seal materials
• Specially designed suction and discharge valves
• Optional seal-flushing arrangement
• Optional heating jacket for temperature-sensitive media
• Optional cooling jacket for process-temperature control
• Optional integrated thermal-insulation jacket
• Easily removable valve assemblies
• Single-head and double-head configurations available
• Different inlet and outlet connections available
• Suitable for continuous industrial operation
• Custom liquid-end materials available for different chemicals