centrifugal pump sizing example|pump type selection chart

Causes of cavitation in centrifugal pumps . Cavitation is a leading cause of pump failure. Since cavitation can result from excessively low pressure at the pump inlet, it can be prevented by ensuring the pressure at the suction end of the pump remains sufficiently above the liquid’s vapor pressure. Factors leading to low inlet pressure:

Centrifugal pumps are widely used in various industries for fluid transportation, and proper sizing is crucial to ensure optimal performance and efficiency. In this article, we will discuss the key factors to consider when sizing a centrifugal pump, as well as provide a step-by-step example of pump sizing calculation.

The head produced by a centrifugal pump is proportional to the velocity attained by the fluid as it exits the vanes at periphery of the impeller. Lets assume 9” dia impeller with 1800 rpm. liquid can be thought of as being caused by a vertical column of the liquid due to its weight.

Factors to Consider in Centrifugal Pump Sizing

When sizing a centrifugal pump, several important factors need to be taken into account to ensure the pump meets the requirements of the application. Some of the key factors include:

Viscosity

Viscosity of the fluid being pumped is a critical factor in pump sizing. Higher viscosity fluids require larger pumps with higher horsepower to overcome the resistance and maintain the required flow rate.

Power Consumption

Power consumption is another crucial factor in pump sizing. It is important to select a pump that can deliver the required flow rate at the specified pressure while minimizing energy consumption to reduce operating costs.

Commercial Availability

Availability of the pump model and spare parts is essential for maintenance and repair. Selecting a pump from a reputable manufacturer with a wide range of products can ensure easy access to replacement parts.

Lifecycle Cost Analysis

Considering the total cost of ownership over the pump's lifespan is important in pump sizing. Factors such as initial cost, maintenance, energy consumption, and downtime should be taken into account to determine the most cost-effective option.

Centrifugal Pump Sizing Example

To illustrate the pump sizing process, let's consider a hypothetical scenario where we need to size a centrifugal pump for a water pumping application. The following steps outline the calculation process:

Step 1: Determine the Required Flow Rate

In this example, the required flow rate is 1000 gallons per minute (GPM).

Step 2: Calculate the Total Dynamic Head (TDH)

The total dynamic head is the sum of the static head (elevation difference) and the friction head (pressure loss in the piping system). Let's assume the TDH is 50 feet.

Step 3: Select a Pump from the Centrifugal Pump Sizing Chart

Refer to the centrifugal pump sizing chart to find a pump that can deliver the required flow rate at the specified TDH. Choose a pump model that falls within the performance curve for the desired operating point.

Step 4: Determine the Pump Efficiency

Calculate the pump efficiency based on the manufacturer's data or performance curve. Efficiency is crucial for determining the power consumption and overall operating costs.

Step 5: Calculate the Required Horsepower

Using the formula: Horsepower (HP) = (Q × TDH) / (3960 × Efficiency), where Q is the flow rate in GPM, TDH is the total dynamic head in feet, and Efficiency is the pump efficiency.

Step 6: Check the Motor Power Rating

Ensure that the pump's required horsepower does not exceed the motor's power rating to prevent overloading and ensure reliable operation.

Step 7: Verify Pump Selection

Perform a final check to verify that the selected pump meets the application requirements and is suitable for the operating conditions.

By following these steps and considering the key factors in centrifugal pump sizing, you can select the right pump for your specific application and ensure efficient and reliable fluid transportation.

To size a pump, you must define: The flow rate of liquid the pump is required to …

The bypass line is to be drawn from the pump's vent port or the discharge pipe's vent port, either back to the suction side (if possible) or into a tank, in order to ensure sufficient cooling by the .

centrifugal pump sizing example|pump type selection chart