The Ultimate Guide to Double Suction Split Case Pumps: Working Principles & Selection

The Double Suction Split Case Pump is a high-flow centrifugal pump that balances axial forces by simultaneously drawing water from both sides, ensuring stable operation and convenient maintenance. It is widely used in municipal water supply, agricultural irrigation, and industrial circulation systems.The horizontal split case pump is highly favored in municipal water supply due to its ease of maintenance.

Double Suction Split Case Pump Structure

The structure of a Double Suction Split Case Pump is relatively simple, yet it harbors many mysteries. Its core components are the pump casing, impeller, and shaft. The pump casing serves as the outer shell of the pump, primarily used for guiding flow and protecting internal structures; the impeller is the most critical component of the pump, responsible for converting mechanical power into the energy of the liquid; while the shaft transmits the power from the motor to the impeller.

1. Pump casing (pump body and pump cover)
Axial split design: The pump casing is horizontally split along the axis, allowing the rotor components to be removed by simply lifting the pump cover during maintenance without the need to disassemble the inlet/outlet pipelines and driving equipment.
Spiral flow passage: The V-shaped spiral channel gradually expands along the outflow direction, maintaining a constant water flow velocity and minimizing energy loss.
Function Extension Interface: The pump housing is equipped with flange holes (for mounting to the foundation), drainage screw holes (to drain liquid when the pump is stopped), and vacuum gauge/pressure gauge mounting holes (for monitoring operational status).

2. Impeller
Dual suction symmetrical structure: The impeller features symmetrically distributed suction ports on both sides, allowing liquid to enter from both left and right channels simultaneously. The flow rate is equivalent to the superposition of two single-suction impellers, with a flow range of 90 to 20,000 m³/h.
Axial force self-balancing: The symmetrical layout of the blades ensures equal hydraulic pressure on both sides, theoretically eliminating residual axial force. The remaining minimal force is supported by bearings, ensuring smooth operation.
Cavitation resistance optimization: The double suction design reduces the inlet flow velocity on one side, minimizing cavitation risks; the closed impeller structure (single/double channel) prevents impurity clogging.

3. Pump shaft and bearing system
High-stiffness pump shaft: Made of high-quality carbon steel, it must meet torsional strength and deflection requirements. The impeller is fixed and the axial position is adjusted via shaft sleeve nuts.
Double bearing support: Two sets of single-row radial ball bearings are installed at both ends of the pump shaft, lubricated with grease or thin oil to reduce friction and extend service life.

4. Sealing System
Double suction sealing ring: Located between the impeller and the pump casing, it reduces backflow losses from the high-pressure zone to the low-pressure zone and can be disassembled and replaced to lower maintenance costs.
Shaft sealing type:
Packing seal: A traditional method that introduces cooling water through a water seal ring to lubricate and prevent air leakage.
Mechanical Sealing: Modern Improved Solution, Requires External Cooling Water Interface, Lower Leakage Rate, Suitable for Harsh Operating Conditions.

5. Auxiliary equipment
Coupling: The elastic pin or metal disc coupling connects the motor and pump shaft, allowing for minor displacement compensation.
Cooling system: Coolant is delivered to the shaft sealing chamber via the pump cover groove or external connecting pipeline to prevent seal overheating and failure.

The mid-opening double-suction centrifugal pump features a unique axial split design and dual-suction impeller, offering significant advantages in flow rate, stability, and maintenance convenience. It is particularly suitable for continuous pumping applications with high flow rates and medium head requirements. The core structural components include a quickly detachable pump casing, self-balancing impeller, and modular bearing system, which collectively support its extensive use in industrial and municipal applications.

Characteristics of Double Suction Pump

• Compact structure: Beautiful appearance, good stability, and easy installation.
• Double suction impeller design: smooth operation, long bearing life;
• Same side layout for import and export: convenient for pipeline layout and installation;
• Highly customizable: The volute, flow-passage components, and sealing form can be flexibly adjusted according to the medium (clean water, sewage, corrosive liquids, etc.);
• Shaft seal: Choose FILIPUSI mechanical seal or packing seal. Can ensure 8000 hours of operation without leakage. Bearings: SKF and NSK bearings are selected to ensure smooth operation, low noise, and long service life.
• Installation form: No adjustment is required during assembly. It can be installed either vertically or horizontally according to the actual usage conditions on site.

Double Suction Split Case Pump working principle

So, what is the working principle of a Double Suction Split Case Pump? After the electric motor is started, it drives the impeller to rotate through the shaft. The rotating impeller generates centrifugal force in the water, causing the liquid to be drawn in from the side of the pump. The liquid moves outward along the pump casing under the action of the impeller and is ultimately discharged through the outlet.

The difference between Horizontal double suction pump and Vertical double suction pump

There are some differences in structure and application scenarios between horizontal double suction pumps and vertical double suction pumps.

In terms of structure, the pump shaft of the horizontal double suction pump is horizontally placed, which makes the pump body relatively flat and occupies a relatively large area. However, it is easy to install and maintain, making it suitable for use in open spaces. The pump shaft of a vertical double suction pump is vertical, with a compact overall structure and a small footprint, which can effectively save space.

In terms of application scenarios, horizontal double suction pumps are commonly used in large-scale water conservancy projects, urban water supply and drainage, and other fields to transport liquids with large flow rates and relatively low head. Vertical double suction pumps are more suitable for places with limited space, such as water supply systems in high-rise buildings, local water supply in factories and workshops, etc. They have obvious advantages in places with high space requirements.

In addition, the stability and efficiency of the two may vary depending on specific operating conditions. When choosing, it is necessary to comprehensively consider factors such as installation space, flow and head requirements to determine which type of double suction pump is more suitable for practical applications.

The horizontal and vertical structures of a double suction pump are essentially single-stage double suction centrifugal pumps (with impeller inlet on both sides and axial force self balancing). The core differences lie in installation methods, spatial layout, maintenance convenience, and applicable scenarios, rather than the double suction function itself.

Application Areas of Double Suction Pumps

Double Suction Split Case Pumps are widely used in multiple fields.

Industrial field: Factory circulating water system, cooling tower water supply, chemical process pressurization;

Municipal engineering: urban water supply plant water intake, booster pump station, drainage system;

Agricultural irrigation: large-scale irrigation area main pump station, drainage and drought resistance;

Mining and Energy: Mine Drainage, Power Plant Condensed Water Circulation;

Petrochemical industry: transporting light oil products and chemical liquids.

FAQ:

1. Is a double suction pump necessarily higher in head than a single suction pump?

The main advantages of a double suction pump are high flow rate, stable operation, and head determined by the impeller diameter and speed, not necessarily higher.

2. Can a double suction pump only pump clean water?

By changing the material (such as stainless steel) and sealing form, sewage, corrosive media, and even light oil products can be transported.

Selection Suggestion: How to Choose a Double Suction Split Case Pump？

1. Clarify the operating conditions: flow rate, head, and medium properties (whether they are corrosive or contain impurities);
2. Focus on efficiency: choose high-efficiency and energy-saving products to reduce long-term operating costs;
3. Emphasize maintainability: Priority should be given to horizontal split structures for easy maintenance in the later stage;
4. Identify the brand and service: Choose manufacturers with accumulated technology (such as FILIPUSI) to ensure quality and after-sales support.

Filipusi Industrial Double Suction Centrifugal Pump, Suitable For Industrial Fluid Transportation Needs In Various Scenarios

As an efficient liquid conveying device, the working principle of a double suction pump is not complicated, but in practical applications, multiple factors need to be comprehensively considered. Whether it's efficiency, traffic, or maintenance, careful consideration should be given when making a purchase. I hope this article can be helpful to you. If you have any questions, please feel free to communicate with us!

If you need to learn more about our products and services, please feel free to contact us at any time.