Depamu Dosing Pump: Hydraulic Diaphragm Metering Pump for Various Chemicals and Water Treatment

Introduction

In the complex landscape of industrial fluid handling, precision, reliability, and safety are paramount. Among the critical equipment that enables accurate chemical dosing across industries, the Hydraulic Diaphragm Metering Pump stands out as a cornerstone technology. Depamu (Hangzhou) Pumps Technology Co., Ltd., established in 2003 and headquartered in Hangzhou Qiantang Area, has emerged as a leading high-tech enterprise specializing in the research, development, production, and sales of metering pumps. With over 4,000 specifications and models of metering pumps and chemical pumps, the company has developed internationally leading Diaphragm Pump technologies and holds more than 20 patents, including five invention patents.

This article provides a comprehensive overview of Depamu's hydraulic diaphragm metering pumps, exploring their design principles, technical specifications, operational advantages, and diverse applications in chemical processing and water treatment.

Understanding Hydraulic Diaphragm Metering Pumps

A metering pump is a positive displacement pump designed to deliver a precise, adjustable flow rate of fluid against varying system pressures. The hydraulic diaphragm metering pump represents an advanced evolution of this technology, utilizing a hydraulic fluid as an intermediary between the driving mechanism and the process diaphragm.

The operating principle is elegant in its simplicity yet sophisticated in execution. The driver, after speed reduction and torque increase through the reducing mechanism, drives a crank connecting rod mechanism that converts the rotary motion of the crankshaft into reciprocating motion of the piston. This piston pushes hydraulic oil within the hydraulic chamber, which in turn transmits the piston thrust force and volumetric change to the hose diaphragm. The diaphragm undergoes cyclical squeezing under the force transmitted by the hydraulic oil, leading to cyclical compression and relaxation of the internal fluid chamber. Continuous fluid delivery is realized under the combined action of inlet and outlet check valve assemblies.

This hydraulic transmission mechanism offers several fundamental advantages over direct mechanical actuation. The hydraulic fluid acts as a cushion, absorbing shock loads and providing smooth, uniform diaphragm movement. It also enables the pump to handle higher pressures while maintaining exceptional metering accuracy.

The Depamu DP(M)WA Series: A Flagship Product Line

The DP(M)WA series represents Depamu's premier hydraulic diaphragm metering pump offering. These pumps are designed with remarkable versatility, allowing the pump head to be configured as hydraulic diaphragm type, plunger type, or piston type to accommodate special working conditions.

Key Technical Specifications

The DP(M)WA series delivers a flow rate adjustment range of 10% to 100% with a metering accuracy of ±0.5%. This exceptional precision ensures that even the most demanding dosing applications can be reliably executed. The pumps accommodate a wide range of motor power options, from 0.37kW to 0.55kW and beyond, with corresponding flow rates and discharge pressures tailored to specific application requirements.

For instance, the DP(M)WA75/2.7/4.0 model delivers a flow rate of 75 L/h at discharge pressures of 2.7 MPa and 4.0 MPa, while the DP(M)WA212/1.0/1.4 provides 212 L/h at 1.0 MPa and 1.4 MPa. This extensive range of models ensures that operators can select the optimal configuration for their specific process requirements.

Patented Transmission Mechanism

A distinguishing feature of Depamu's hydraulic diaphragm pumps is the patented integrated sleeve adjustable eccentric transmission mechanism. This design is both simple and reliable, enabling stroke adjustment from 0% to 100% in a stepless manner. The mechanism incorporates a low-speed high-load connecting rod with roller bearing connection, which features a small friction coefficient and low heat emission compared with traditional bushing connections. Unlike bushing connections that cannot form an oil film under low-speed operation, the roller bearing connection fully meets the pump's requirements for low-speed operation and high bearing capacity.

The transmission mechanism employs an integrated "Oude" worm gear pair, delivering low noise and high efficiency. Oil-immersion lubrication ensures reliable long-term use of the transmission mechanism.

Flow Rate Adjustment Flexibility

Depamu hydraulic diaphragm metering pumps offer diversified flow rate adjustment modes to suit various operational requirements. Operators can choose from manual, electrical, pneumatic, or frequency conversion adjustment. When equipped with an electric actuator, the pump can achieve remote automatic control, integrating seamlessly into modern automated process control systems.

Advanced Diaphragm Technology

The diaphragm is the heart of any hydraulic diaphragm pump, and Depamu has invested heavily in diaphragm technology. The company utilizes Rite PTFE polymer composite diaphragms that undergo multi-directional rolling and surface quenching treatment, achieving a homogenization degree of 99.92%. This advanced processing reduces cold flow phenomena during operation and improves compressive strength. The limit valve achieves precision of ±0.002mm with surface hardness reaching 60-70HRC and roughness of 0.4μm, enabling reliable operation for 80 million cycles across temperatures ranging from -80°C to 160°C.

The DP(M)XAA Series: Enhanced Capabilities

The DP(M)XAA series builds upon the foundation of the DP(M)WA line with additional capabilities. These hydraulic diaphragm metering pumps can be configured with two or more pump heads connected in parallel, up to a maximum of 12 heads. This multi-head configuration offers significant operational advantages: multiple pump heads can deliver the same medium to reduce pulsation, or they can deliver different media simultaneously, functioning as a proportioning pump. Each pump head can have independent flow adjustment, providing exceptional flexibility in complex dosing applications.

Safety and Reliability Features

Internal Safety and Compensation Valves

Depamu hydraulic diaphragm pumps incorporate internal safety valves and compensation valves that realize automatic air discharge and oil replenishment. This automatic system ensures outstanding and reliable performance without requiring manual intervention for routine hydraulic system maintenance.

Dual Diaphragm and Rupture Alarm Systems

When conveying toxic, flammable, explosive, or highly corrosive hazardous media, Depamu pumps can be equipped with dual or multi-diaphragm configurations. A rupture alarm device prevents contact between the medium and hydraulic oil in the event of diaphragm failure, averting potentially dangerous situations. This real-time monitoring capability ensures absolutely secure delivery without leakage.

Leak-Free Operation

The vertical motor installation ensures safety without leakage. High-performance plungers, special packing, diaphragms, and sealing components provide long service life and excellent sealing performance. The separation of the process fluid from the pump head by the diaphragm means no wearing parts come into contact with the pumped medium and no leakage occurs.

API 674 Compliance

Depamu's Reciprocating Pumps are designed according to the American Petroleum Institute standard API 674. This international standard ensures that the pumps meet the most stringent requirements for quality, reliability, and performance in demanding industrial applications.

Applications in Chemical Processing

The versatility of Depamu hydraulic diaphragm metering pumps makes them indispensable across a wide spectrum of chemical processing applications. These pumps are widely used in industries including petrochemical, coal chemical, lithium battery, new materials, mining, metallurgy, energy, environmental protection, and pharmaceuticals.

Handling Challenging Chemicals

Depamu pumps are particularly well-suited for delivering highly viscous fluids, fluids containing particles, and corrosive chemicals. The hydraulic diaphragm design isolates the pumped medium from mechanical components, making these pumps ideal for handling:

• Acids and alkalis: The pumps can be configured with wetted parts in 304, 316, 316L stainless steel, PVC, PVDF, PP, or PTFE to match specific chemical compatibility requirements.

• Flammable liquids: The leak-free design and vertical motor installation ensure safe handling of flammable and explosive chemicals.

• Toxic and hazardous substances: Dual diaphragm configurations with rupture alarms provide an additional layer of safety when handling dangerous materials.

• High-temperature fluids: The pumps can operate with fluid temperatures up to 160°C.

• High-viscosity fluids: The positive displacement design ensures consistent delivery regardless of fluid viscosity.

Proportioning and Blending Applications

The multi-head configuration capability enables sophisticated proportioning applications. Multiple pump heads can deliver different chemicals simultaneously in precise ratios, functioning as an integrated proportioning pump. This is particularly valuable in chemical manufacturing processes requiring precise ingredient ratios.

Applications in Water Treatment

Water treatment represents one of the most significant application areas for Depamu hydraulic diaphragm metering pumps. These pumps are essential components in municipal water treatment, industrial water and wastewater treatment, and swimming pool water treatment processes.

Municipal Water Treatment

In drinking water treatment plants, Depamu pumps are used for precise chemical dosing including:

• Disinfection: Accurate metering of chlorine, sodium hypochlorite, or other disinfectants

• pH adjustment: Dosing of acids or alkalis for pH control

• Coagulation and flocculation: Precise addition of alum, ferric chloride, or polymer coagulants

• Fluoridation: Accurate fluoride dosing for dental health

• Corrosion control: Injection of corrosion inhibitors and pH adjusters

Industrial Water Treatment

Industrial facilities rely on Depamu pumps for a variety of water treatment applications:

• Boiler water treatment: Phosphate injection for scale control, oxygen scavengers, and pH adjusters

• Cooling water treatment: Biocide, corrosion inhibitor, and scale inhibitor dosing

• Process water treatment: Chemical addition for various manufacturing processes

Wastewater Treatment

In wastewater treatment facilities, Depamu pumps handle:

• Nutrient removal: Precise dosing of chemicals for phosphorus and nitrogen removal

• Polymer dosing: Accurate polymer addition for sludge dewatering and thickening

• Disinfection: Chlorine or other disinfectant dosing for effluent disinfection

• Odor control: Chemical injection for hydrogen sulfide and odor control

Integrated Dosing Packages

Depamu offers integrated dosing packages that combine metering pumps with solution tanks, mixers, level gauges, and control systems. These packages achieve functions of chemical dissolving, preparation, metering, and injection in a single, coordinated system. Common configurations include one tank with two pumps (working and standby) or two tanks with three pumps, providing redundancy and operational flexibility.

Operational Advantages

Precision and Accuracy

With a metering accuracy of ±0.5% across a 10%-100% flow adjustment range, Depamu hydraulic diaphragm pumps deliver the precision required for critical dosing applications. High-precision inlet and outlet check valves effectively guarantee metering accuracy and fluidity.

Reliability and Long Service Life

The combination of oil-immersion lubrication, high-performance materials, and robust construction ensures long-term reliable operation. The pumps are designed for continuous duty in demanding industrial environments, with components engineered for extended service life.

Low Maintenance

The modular design and accessible components facilitate maintenance. The automatic air discharge and oil replenishment system reduces the need for routine hydraulic system maintenance. The roller bearing connection in the connecting rod allows low-speed operation (rated speed below 60 r/min) with minimal wear.

Environmental Safety

The leak-free design and diaphragm isolation of the process fluid from mechanical components ensure that no leakage occurs. This is particularly important when handling hazardous or environmentally sensitive chemicals. The pumps' ability to handle high solid content fluids (up to 80%) without leakage further extends their environmental safety credentials.

Global Reach and Industry Recognition

Depamu has established a strong presence in the global market, with products supplied to countries including Germany, Israel, Ukraine, the United Kingdom, Italy, Argentina, France, and Brazil. The company has completed major contracts including the world's largest Indian oilfield polymer high-pressure reciprocating pump project. Depamu products have been deployed in demanding applications such as Arctic natural gas extraction, where the company's hydraulic diaphragm metering pumps met extreme cold conditions and special medium delivery requirements.

Conclusion

Depamu hydraulic diaphragm metering pumps represent a sophisticated solution for precise chemical dosing across a wide range of industries. The combination of advanced hydraulic transmission technology, patented mechanical designs, high-performance mat