Choosing the right centrifugal pump is critical to ensuring system effectiveness and reliability.

The following are detailed data and steps for centrifugal pump selection:

1.Determine demand parameters

1.1 Flow (Q)

• definition: The amount of liquid delivered by a centrifugal pump per unit time.
• unit: Cubic meters per hour (m3/h) or liters per second (L/s).
• Determining method: Determined based on the design specifications and actual needs of the system. Generally, the flow rate should meet the water demand at the most unfavorable point.
  • residential building: Usually 10-50 m3/h.
  • commercial building: Usually 30-150 m3/h.
  • industrial facilities: Usually 50-300 m3/h.

1.2 Lift (H)

• definition: Centrifugal pumps can raise the height of liquid.
• unit: Meter (m).
• Determining method: Calculated based on the height of the system, the length of the pipe and the resistance loss. The head should include static head (building height) and dynamic head (pipeline resistance loss).
  • Quiet lift: The height of the system.
  • moving lift: The length and resistance loss of the pipeline, usually 10%-20% of the static head.

1.3 Power (P)

• definition: The power of the centrifugal pump motor.
• unit: kilowatt (kW).
• Determining method: Calculate the power requirement of the pump based on the flow rate and head, and select the appropriate motor power.
  • Calculation formula：P = (Q × H) / (102 × η)
    • Q: Flow rate (m3/h)
    • H: Lift (m)
    • η: Pump efficiency (usually 0.6-0.8)

1.4 Media characteristics

• temperature: The temperature range of the medium.
• viscosity: The viscosity of the medium, usually in centipoise (cP).
• corrosive: The corrosiveness of the medium, choose the appropriate pump material.

2.Select pump type

2.1 Single-stage centrifugal pump

• Features: Simple structure, smooth operation and high efficiency.
• Applicable occasions: Suitable for most water supply and drainage systems.

2.2 Multi-stage centrifugal pump

• Features: Through multiple impellers connected in series, high-lift water supply is achieved.
• Applicable occasions: Suitable for occasions requiring high lift, such as water supply for high-rise buildings.

2.3 Self-priming centrifugal pump

• Features: With self-priming function, it can automatically suck in liquid after starting.
• Applicable occasions: Suitable for ground-mounted water supply and drainage systems.

2.4 Double suction centrifugal pump

• Features: Double-side water inlet design can provide larger flow rate and higher lift at lower speed.
• Applicable occasions: Suitable for large flow and high head situations, such as municipal water supply and industrial water supply.

3.Select pump material

3.1 Pump body material

• cast iron: Common material, suitable for most occasions.
• Stainless steel: Strong corrosion resistance, suitable for corrosive media and occasions with high hygiene requirements.
• bronze: Good corrosion resistance, suitable for seawater and other corrosive media.

3.2 Impeller material

• cast iron: Common material, suitable for most occasions.
• Stainless steel: Strong corrosion resistance, suitable for corrosive media and occasions with high hygiene requirements.
• bronze: Good corrosion resistance, suitable for seawater and other corrosive media.

4.Select make and model

• Brand selection: Choose well-known brands to ensure product quality and after-sales service.
• Model selection:Select the appropriate model based on demand parameters and pump type. Refer to the product manuals and technical information provided by the brand.

5.Other considerations

5.1 Operational efficiency

• definition: The energy conversion efficiency of the pump.
• Select method: Choose a pump with high efficiency to reduce operating costs.

5.2 Noise and vibration

• definition: Noise and vibration generated when the pump is running.
• Select method: Choose a pump with low noise and vibration to ensure a comfortable operating environment.

5.3 Maintenance and care

• definition: Pump maintenance and service needs.
• Select method: Choose a pump that is easy to maintain and maintain to reduce maintenance costs.

6.Instance selection

Assume that a centrifugal pump needs to be selected for a high-rise residential building. The specific demand parameters are as follows:

• flow：40 m3/h
• Lift:70 meters
• power: Calculated based on flow rate and head

6.1 Select pump type

• Multistage centrifugal pump: Suitable for high-rise residential buildings and capable of providing high-lift water supply.

6.2 Select pump material

• Pump body material: Cast iron, suitable for most occasions.
• Impeller material: Stainless steel, strong corrosion resistance.

6.3 Select brand and model

• Brand selection: Choose well-known brands, such as Grundfos, Wilo, Nanfang Pump Industry, etc.
• Model selection: Select the appropriate model based on the demand parameters and the product manual provided by the brand.

6.4 Other considerations

• Operational efficiency: Choose a pump with high efficiency to reduce operating costs.
• Noise and vibration: Choose a pump with low noise and vibration to ensure a comfortable operating environment.
• Maintenance and care: Choose a pump that is easy to maintain and maintain to reduce maintenance costs.

Through these detailed selection guidance and data, you can ensure that the appropriate centrifugal pump is selected to effectively meet the needs of the water supply system and ensure that it can provide stable and reliable water supply in daily operations.