When a water circulation system needs to move large volumes of water, few technologies are as proven as the horizontal split case pump. From HVAC systems and municipal water distribution to industrial plants and fire protection systems, split case pumps are widely used for their durability, high efficiency, and ease of maintenance.
But many engineers, facility managers, and procurement teams still ask the same question:
When should you use a split case pump instead of another pump type?
In this guide, we’ll explain what a split case pump is, how it works, where it performs best, and why the Grundfos KP horizontal split case pump series continues to be a preferred solution across multiple industries.
What Is a Split Case Pump?
A split case pump is a centrifugal pump with a casing split into two parts, connected in the middle of the arrangement. This design allows technicians to access internal components without disturbing the piping system or motor components alignment, making maintenance significantly easier than with many traditional pump designs.
There are two possible arrangements, horizontal and vertical mounting.
These pumps are engineered for:
- High flow rates
- Continuous-duty operation
- Energy-efficient performance
- Long service life
- Simplified maintenance access
Because of these advantages, split case pumps are widely used in critical water-movement applications where downtime is costly.
Video credit: Caprari Group
How Does a Split Case Pump Work?
In simple words, a split case pump uses a double-suction rotating impeller to move water through the split pump casing. Due to their arrangement, maintenance is easier than in other pump designs, as split case pumps can be serviced without disturbing the motor alignment. When the water enters the suction side, it is accelerated through the impeller and exits the discharge side under pressure. This pump style reduces shaft deflection, minimizes bearing wear, and allows the pump to operate smoothly even under demanding conditions.
Key Components of a Split Case Pump
- Pump Casing - The casing is split into two halves, upper and lower, which is a main characteristic of this pump style. It allows maintenance access without disconnecting pipework while maintaining motor alignment.
- Double-Suction Impeller - The impeller draws water from both sides, balancing axial loads and improving hydraulic efficiency.
- Shaft & Bearings - Heavy-duty shafts and bearings support long-term continuous operation.
- Mechanical Seals / Packing - Prevent leakage while maintaining operational efficiency.
- Coupling & Motor - Transfer rotational power to the pump assembly.
Split Case Pump - Common Applications
Several applications require a robust, split case pump arrangement, and the correct pump selection depends on flow requirements, pressure demands, maintenance expectations, and system design. Split case pumps are typically the best option when the application requires:
- High flow rates
- Continuous operation
- Maximum energy efficiency
- Low maintenance downtime
- Long equipment lifespan
- Reliable water transfer
Below are the most common situations in which split case pumps outperform other pump types:
Large HVAC Systems
One of the most common applications of horizontal split case pumps is HVAC circulation in commercial and industrial facilities.
These systems require continuous water circulation for:
- Chilled water loops
- Condenser water systems
- Heating systems
- District cooling systems
For some HVAC systems operating 24/7, pump efficiency directly affects energy consumption and operating costs.
Municipal Water Distribution
Municipal water distribution centers frequently use split case pumps to move extremely high volumes of water reliably.
Typical applications include:
- Water treatment plants
- Booster stations
- Distribution networks
- Raw water transfer
- Irrigation infrastructure
The robustness of a split case centrifugal pump makes it ideal for critical infrastructure where failure is not an option.
Industrial Water Transfer
Industrial facilities are well known to require robust pumping systems capable of handling demanding operating conditions.
Common industrial uses include:
- Process water circulation
- Cooling systems
- Plant utilities
- Mining operations
- Manufacturing plants
In these environments, maintenance used to be critical and not easy; most of the time, accessibility might be an issue. Since the casing of a split case pump opens easily, service teams can inspect internal components quickly, with minimal downtime.
Fire Protection Systems
Many large commercial and industrial fire protection systems rely on split case pumps, especially for easy access to the pump parts, which involves removing one of the case parts.
Fire protection systems must deliver high water flow during emergencies.
A split case pump diagram typically shows:
- Double-suction impeller
- High-flow discharge configuration
- Redundant reliability features
- Heavy-duty bearings and shafts
Because fire systems are mission-critical, the durability and reliability of split case pumps make them a preferred technology for fire protection applications.
Horizontal vs. Vertical Split Case Pumps
Split case pumps are available in horizontal and vertical designs. A horizontal arrangement remains more common for many industrial applications. and are typically preferred for applications requiring easy maintenance and high flow rates. At the same time, vertical arrangement is more appropriate when space is limited, and a smaller installation footprint is critical.
The table below highlights the main features and most appropriate usage for each type:
| Feature | Horizontal Split Case Pump | Vertical Split Case Pump |
| Common Advantage | Easier maintenance | Space-saving design |
| Primary Limitation | Larger footprint | More complex servicing |
| System Expansion Flexibility | Easier to expand | Expansion more constrained |
| Downtime During Service | Lower due to easier access | Longer downtime |
| Space Requirements | Larger room needed | Tight or vertical spaces |
| Initial Cost | Typically lower cost | Higher cost due to installation |
| Installation Complexity |
Simpler installation | Specialized installation |
| Maintenance Access | Easier access | More difficult access |
| Pump Orientation | Shaft horizontally mounted | Shaft vertically mounted |
What Makes the Grundfos Split Case Pumps Different?
The KP and KPV split case pump series are often still searched for as PACO KP pumps, or PACO KPV pumps, because these product lines were originally associated with the pump manufacturer PACO, which was formally acquired by Grundfos years ago. Today, they are part of the Grundfos split case pump portfolio.
This is an important point for customers working on replacements. Many existing installations, nameplates, old submittals, and maintenance records may still reference PACO KP or PACO KPV. However, when selecting a new pump, reviewing current documentation, or using the Grundfos Product Selection tool, these models are now found under the Grundfos offering.
In practical terms, customers searching for a PACO split case pump replacement are often looking for the current Grundfos-supported version of the same pump family:
- Horizontal Split Case Pump - KP Series
- Vertical Split Case Pump - KPV Series
Each model has its own strengths and constraints, outlined in the breakdown below.
Horizontal Split Case Pump - KP Series
KP Series Technical Data
- Water Flow, Q: - Max. 20,000 gpm
- Head, H: Max. 700 ft
- Liquid Temperature: -20°F to 275°F
- Working Pressure: Max. 400 psi
- HP Range: Max. 2000 HP
- Discharge Sizes: 2 to 10 in
- Impellers: 7to 24 in
KP Series Performance Data
KP Series Key Features
- The hydraulic double-volute design reduces radial loads, internal recirculation, and turbulence, resulting in a longer pump lifespan and higher operational efficiency.
- The axially split design allows quick removal of the top casing and access to pump components (bearings, wear rings, impeller, and shaft seal) without disturbing the motor or pipework, saving time and money.
- Standard bronze wear rings protect the pump from erosion and permit simple maintenance of proper running clearances.
- Horizontal, space-saving design eliminates the need for a maintenance access distance around the pump.
- Highly customizable construction, including choices of case material with numerous impeller and shaft seal options.
- Integrally cast suction baffles reduce suction recirculation loss and ensure even flow distribution and quiet, vibration-free operation.
- The suction chamber inlet configuration also increases hydraulic efficiency and reduces net positive suction head requirements.
- Independent bearing housing design allows access to the pump components without removing the top half of the casing.
- An extended pump range up to 20,000 gallons per minute to serve all your high-flow applications.
- Francis Vane Impeller design with extended vanes and enlarged eye increases efficiency and reduces vibration and noise.
Vertical Split Case Pump - KPV Series
KPV Series Technical Data
- Water Flow, Q: - Max. 8,000 gpm
- Head, H: Max. 420 ft
- Liquid Temperature: -20°F to 275°F
- Working Pressure: Max. 400 psi
- HP Range: Max. 500 HP
- Discharge Sizes: 2 to 10 in
- Impellers: 7to 24 in
KPV Series Performance Data
KPV Series Key Features
- The lower sleeve bearing, with its liquid-cooling design, delivers leak-free performance and reduces maintenance costs by eliminating the need for a mechanical lower seal.
- Spiral grooves on sleeve bearings flush contaminants and particles through the recirculation line, reducing maintenance needs.
- Highly customizable construction, including choices of case material with numerous impeller and shaft seal options.
- Vertical design provides further space savings over the already compact KP model.
How to Choose the Right Horizontal Split Case Pump
As highlighted in this article, selecting the correct split case pump requires evaluating several factors. We've listed the main ones that will make a difference for an optimum pump selection:
- Flow Rate Requirements: Determine the required gallons per minute (GPM) or cubic meters per hour.
- Total Dynamic Head (TDH): Calculate the pressure the system requires.
- Fluid Characteristics: Consider temperature, viscosity, corrosiveness, and solids content.
- Efficiency Targets: High-efficiency pumps reduce long-term operating expenses.
- Maintenance Accessibility: Applications requiring continuous operation benefit greatly from split case serviceability, with the type chosen depending on the available installation space.
Using the Grundfos Product Selection Website for Sizing
Any pump selection requires more than simply choosing flow and pressure ratings; additional variables must be considered to ensure an optimal selection.
The Grundfos Selection website helps engineers, contractors, and facility managers:
- Size pumps accurately.
- Compare performance curves.
- Analyze energy consumption.
- Select appropriate configurations.
- Review technical documentation.
You can find the Grundfos Selection Tool Website at this link.
If you have any questions, don't hesitate to reach out to our Sales team for further KP/KPV Series selection support.
Frequently Asked Questions
A split case pump is a type of centrifugal pump with a casing that splits horizontally or vertically along the shaft centerline. This design allows easy access to internal components for maintenance without removing the piping system. These pumps are commonly used in HVAC, municipal, industrial, and fire protection applications.
A split case pump is ideal when an application requires high flow rates, Continuous-duty operation, High energy efficiency, Easy maintenance access, a Long equipment lifespan, and Reliable water transfer.
Horizontal split case pumps are easier to maintain and preferred for high-flow industrial and municipal applications. Vertical split-case pumps require less floor space and are often used where installation space is limited.
Important selection factors include: Required flow rate, Total dynamic head (TDH), Fluid type and temperature, System pressure requirements, Efficiency goals, and Available installation space.
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