DHP 26 Axial Piston Pumps(High Pressure Pump For Industrial Reverse Osmosis)

The DHP 26 Axial Piston Pump is a High Pressure Pump For Industrial Reverse Osmosis developed by Wuxi Fenigal Science and Technology Co., Ltd. in collaboration with its OEM partner, Shenzhen CW Environment Technology. Specifically designed for conveying high-pressure, extra-large-flow, low-viscosity corrosive fluids in industrial reverse osmosis systems, it serves as a core power equipment for scenarios such as large-scale seawater desalination plants, industrial park wastewater zero-liquid discharge projects, and large-scale concentration of high-concentration raw material liquids.

As an important member of the large-flow models in Fenigal’s DHP series, the DHP 26 inherits the brand’s technical mission since it launched the R&D of high-pressure plunger pumps in 1990. From breaking the technical monopoly of foreign equipment to realizing domestic substitution, Fenigal has always focused on industry pain points of traditional plunger pumps, such as "oil leakage pollution, weak corrosion resistance, and high operation & maintenance costs", and the DHP 26 has achieved comprehensive optimization and upgrading based on these. It operates on the axial piston principle, realizing high-pressure fluid conveyance through the reciprocating motion of plungers parallel to the drive shaft within plunger bores, which creates volume changes. Its core technical highlight lies in the "fluid self-lubrication design"—using the conveyed liquid as the lubricating medium, it completely eliminates the lubricating oil tank of traditional plunger pumps, fundamentally preventing oil leakage from contaminating reverse osmosis media. This makes it particularly suitable for large-scale membrane concentration processes in the food and pharmaceutical industries that have strict requirements on medium purity (such as juice concentration and purification of traditional Chinese medicine extracts). Meanwhile, the DHP 26 is integrated with a flush check valve, which forces one-way fluid flow when the pump is stopped, preventing medium backflow from damaging pump body seals and reverse osmosis membrane elements, and greatly improving the operational safety and stability of the system.

In terms of materials and performance, the key components of the DHP 26 are made of 2205 duplex stainless steel (SAF 2205 / EN 1.4462 / UNS 31803), providing excellent resistance to high salt and strong corrosion. It can withstand highly corrosive fluids such as seawater, desulfurization wastewater from coal-fired power plants, and high-salt chemical wastewater for a long time. During operation, through the optimized arrangement of multiple plungers, the pulsation amplitude is controlled to be much lower than that of centrifugal pumps, with noise ≤85 dB(A), making it suitable for scenarios sensitive to operating noise such as municipal water supply stations and food processing workshops. Its compact structure allows direct installation on motors or internal combustion engines without occupying additional large space, making it applicable to space-constrained but extremely high-flow-demand scenarios such as large coastal factories and large-scale island desalination stations.

In terms of application scenarios, as a High Pressure Pump For Industrial Reverse Osmosis, the DHP 26 is widely used in three core fields: (1) Large-scale seawater and brackish water desalination systems in coastal cities and large industrial parks, providing stable high-pressure power for centralized municipal water supply and industrial production, with a single pump capable of meeting the daily water supply demand of 12,000-ton level; (2) Zero-liquid discharge treatment of high-salt industrial wastewater, such as desalination and salt concentration of printing and dyeing, chemical, and coal coking wastewater, helping enterprises achieve water resource recycling and environmental compliance; (3) Large-scale raw material liquid membrane concentration processes in the food and pharmaceutical industries, meeting high hygiene standards and medium purity requirements. Its technical level and product quality have reached the world’s advanced level, and it can stably meet the long-term continuous operation needs of various large-scale industrial reverse osmosis systems.

Core Technical Parameters

The technical parameters of the DHP 26 high-pressure plunger pump cover key indicators such as geometric displacement, flow rate, pressure, rotation speed, power, and temperature adaptability, which are the core basis for system selection, equipment matching, and energy consumption calculation. The specific parameters are shown in the table below:

Flow Characteristics at Different Rotation Speeds

As a fixed-displacement axial piston pump, the flow rate of the DHP 26 has a strictly proportional relationship with the input shaft rotation speed (the flow rate/rotation speed ratio is fixed). The flow rate required by the system under different working conditions (such as reverse osmosis system startup/shutdown, load adjustment, and membrane cleaning) can be flexibly matched by adjusting the motor rotation speed. If the actual flow rate required by the system is known, the corresponding motor rotation speed can be accurately calculated using the following formula to maximize the pump operation efficiency and avoid energy waste:
Selected Motor Rotation Speed (r/min) = (Required Flow Rate (m³/h) × Rated Rotation Speed (1500 r/min)) / Rated Flow Rate (26.7 m³/h)

The figure below shows the flow rate-rotation speed curve of the DHP 26 at 80 Bar pressure, which allows for an intuitive view of the actual flow rate corresponding to different rotation speeds (e.g., approximately 12.4 m³/h at 700 rpm, approximately 21.4 m³/h at 1200 rpm, and the rated 26.7 m³/h at 1500 rpm). It provides a visual reference for system rotation speed matching, frequency conversion motor selection, and flow rate adjustment, helping engineers quickly complete system parameter design and optimization:

Installation and Operation Specifications

As a High Pressure Pump For Industrial Reverse Osmosis, the DHP 26 must be installed and operated in strict accordance with specifications to ensure stable system operation, extend the pump’s service life, and avoid safety risks. The core points are as follows:

1. Filtration Requirements: Since reverse osmosis media (such as seawater and high-salt wastewater) may contain tiny particle impurities (such as sediment, suspended solids, and pipeline welding slag), a depth filter with an accuracy of 10 μm (absolute accuracy) must be installed at the inlet of the DHP 26. It is required to have a filtration efficiency of 99.98% for particles larger than 10 μm (β10>5000). The precision clearance between the plunger and plunger sleeve inside the pump is extremely small (only 0.005-0.01 mm, used to control internal leakage and improve operation efficiency); if particles enter, they will cause rapid component wear, seal failure, and even pump jamming. The use of bag filters with only 90% efficiency is prohibited; spiral-wound filter elements are recommended to ensure filtration effectiveness, and the filter elements should be replaced regularly (it is recommended to replace them every 3 months or when the pressure difference reaches 0.2 Bar, and the filter housing should be flushed after replacement).

2. Pressure Control: A low-pressure control switch (set to 1 Bar) must be installed at the inlet to automatically shut down the pump when the inlet pressure is lower than 1 Bar, preventing cavitation from damaging the plunger and seals. A high-pressure control switch (set to 70 Bar) must be installed between the outlet and the reverse osmosis membrane to shut down the pump immediately when the pressure exceeds the limit. At the same time, a safety valve conforming to the specifications in Chapter 10 of the document (pressure set to 75 Bar) must be installed to avoid damage to membrane elements or pipelines caused by instantaneous high pressure after the pump starts (the safety valve should be calibrated every 6 months to ensure accurate pressure relief).

3. Pre-Startup Preparation: Before startup, thoroughly flush the pipelines and system to remove residual welding slag, debris, etc. (it is recommended to circulate and flush with clean water for more than 30 minutes until the outlet water is clear); discharge the air from the pump and system through the exhaust valve on the top of the pump body to prevent cavitation (open the exhaust valve slowly during air discharge to avoid medium splashing); confirm that the pump rotation direction is consistent with the arrow on the pump body (clockwise direction when viewed from the motor end). Starting the pump with the outlet valve closed is strictly prohibited (as it may cause frequent operation of the safety valve, pump body overpressure, or pipeline burst).

The figure below shows the standard connection method between the DHP series high-pressure pump and the motor. When installing the DHP 26, ensure that the coupling clearance is at least 3-5 mm and that there is no axial/radial load on the pump shaft (it is recommended to use a laser alignment tool to calibrate the coaxiality, with coaxiality error ≤0.1 mm) to avoid bearing wear, seal leakage, or motor overload caused by misalignment:

Detailed Power Parameters

The power consumption of the DHP 26 changes with the operating pressure. The power values at different typical pressures directly affect motor selection, cable selection, and system energy consumption calculation. The table below shows the power parameters of the DHP 26 at different pressures, which can be used as the core basis for motor matching (e.g., matching a 75 kW motor can meet the rated operation requirements at 80 Bar and avoid faults caused by motor overload; if the system operates at 60 Bar for a long time, a 55 kW motor can meet the demand, reducing initial investment and operating energy consumption):

Outline and Installation Dimensions

The outline dimensions of the DHP 26 (especially the inlet and outlet interface dimensions) and the installation dimensions of the complete equipment (including the frequency conversion motor) are the key basis for pipeline connection design, on-site layout planning, and equipment foundation construction. The details are as follows:

1. Interface Dimensions: Both the inlet and outlet of the DHP 26 feature M60×1.5 threads with a depth of 23 mm. High-pressure pipe fittings of the corresponding specifications (refer to the "High-Pressure Hose Connector" specifications in Chapter 11 of the document; DN 50 or DN 65 high-pressure hoses are recommended) must be matched to ensure the sealing performance of the interface (metal-clad gaskets are recommended, with sealing pressure ≥100 Bar) and avoid safety risks and efficiency losses caused by high-pressure fluid leakage.

2. Complete Equipment Dimensions: When the DHP 26 is equipped with an independent fan motor (frequency conversion motor), the installation dimensions corresponding to motors of different powers are shown in the table below (Unit: mm), which can be used for on-site space planning, equipment fixing design (foundation load-bearing ≥500 kg, foundation flatness error ≤2 mm), and surrounding pipeline arrangement (it is recommended to reserve ≥100 mm expansion space for inlet and outlet pipelines to prevent pipeline stress from being transmitted to the pump body due to temperature changes):

The figure below is the outline structure diagram of the DHP 26, clearly marking the positions of key components such as the inlet, outlet, installation interface, exhaust hole, and temperature sensor interface, facilitating quick positioning and pipeline connection by on-site installers (it is recommended to reserve ≥500 mm maintenance space during installation to facilitate subsequent maintenance operations):

High-Pressure Piston Pump Maintenance and Warranty Services

Maintenance Recommendations

Although the DHP 26 adopts a self-lubricating design (no lubricating oil required), proper maintenance can significantly extend the equipment’s service life (designed for over 8000 hours of operation) and reduce operation & maintenance costs. The core maintenance points are as follows:

• Daily Maintenance: During operation, real-time monitoring of the pump’s noise (≤85 dB(A) during normal operation; investigation is required if it exceeds this value), vibration (amplitude ≤0.1 mm; shutdown inspection is required if it exceeds this value), and inlet/outlet pressure (inlet pressure 1-5 Bar, outlet pressure ≤80 Bar; vigilance is required if pressure fluctuation exceeds ±5 Bar) is required. When operating in a high-salt environment (such as seawater desalination), the pump cavity must be flushed with fresh water after each shutdown (flushing time ≥5 minutes, flushing flow rate ≥12 m³/h) to discharge residual concentrated brine and prevent salt crystallization from damaging the plunger and seals—during flushing, the pump can be started briefly (10-20 seconds) to ensure complete discharge of residual brine in the pump cavity.

• Shutdown Maintenance: For short-term shutdowns (≤3 days), no flushing is required; the pump only needs to be kept filled with the medium. For medium-term shutdowns (3～15 days), the pump cavity and inlet/outlet pipelines must be thoroughly flushed with fresh water (it is recommended to close the inlet and outlet valves after flushing to prevent air from entering). For long-term shutdowns (>15 days), the pump must be flushed with fresh water containing food-grade bactericide (such as sodium hypochlorite, concentration 50-100 ppm) to prevent microbial growth from causing component corrosion. After flushing, the pump inlet and outlet must be sealed (plastic plugs are recommended to prevent impurities from entering).

• Regular Inspection: A comprehensive disassembly and inspection is recommended after 8000 hours of operation. Worn parts (such as seal plates, plunger sleeves, and springs) should be replaced, and the plunger clearance should be calibrated after replacement. At the same time, check the tightness of the check valve (qualified if the pressure drop is ≤0.5 Bar within 30 minutes through the pressure holding test) and the wear of the inlet/outlet interface threads (repair or replace the joint in a timely manner if thread damage occurs). In addition, check the wear of the coupling elastic pad; if cracks or deformation occur, replace it immediately to avoid vibration transmission.

Warranty Service Details

Fenigal provides comprehensive warranty and maintenance services for the DHP 26, covering the full-life-cycle usage needs of the equipment. The specific service contents are shown in the table below:

For maintenance or warranty inquiries, please contact Wuxi Fenigal Science and Technology for professional support:

• Address: Chuangyi Chanye Park, No. 100 Dicui Road, Binhu District, Wuxi City, Jiangsu Province, P. R. China

• Tel: +86-510-85163211

• Email: [email protected]

• Official Website: https://www.fgwater.com

• PDF manual download address:DHP type plunger pump selection manual.pdf