Water supply, wastewater treatment, and mining all rely on submersible axial flow pumps as essential equipment. If you want your operations to run as smoothly and effectively as possible, knowing how to calculate these pumps' flow is essential. Performance parameters, calculation methods, pump selection, and practical considerations are all covered in this comprehensive guide to submersible axial flow pump flow calculation.

Pump Performance Parameters

Understanding the key performance parameters that influence pump operation is essential for accurately calculating a submersible axial flow pump's flow. The flow rate, head, power, and efficiency are some of these parameters.

The volume of liquid that can be moved by the pump in a given amount of time is represented by the flow rate, which is typically expressed in gallons per minute (GPM) or cubic meters per hour (m3/h). We are primarily interested in calculating or confirming this parameter.

The pressure or height to which the pump is capable of lifting liquid is known as head, and it is measured in feet or meters. It is a combination of dynamic head (pressure losses caused by friction in pipes and fittings) and static head (the vertical distance between the pump and the discharge point).

The amount of energy required to run the Submersible axial flow pump is referred to as power, and it is typically measured in kilowatts (kW) or horsepower (HP). It has a direct connection to the head and flow rate.

Efficiency is the ratio of the pump's useful work to its total energy input. The pump is converting more of the input power into useful work when its efficiency is higher.

The pump's performance is determined by the interaction of these parameters. We must take into account how changes in one parameter might affect the others when calculating flow. For instance, increasing the head typically results in a decrease in the flow rate, whereas increasing the power might result in an increase in both the flow rate and the head.

Flow Calculation Methods

A Submersible axial flow pump's flow can be estimated or calculated in a number of ways. Utilizing the pump curve graph provided by the manufacturer and applying affinity laws for various operating conditions are the approaches that are utilized the most frequently and are the most accurate.

Pump Curve Technique:

The siphon bend, otherwise called the exhibition bend, is a chart that shows the connection between stream rate and set out toward a particular siphon model. To apply this strategy:

1. Look in the manufacturer's documentation for the pump curve graph.

2. Find the operating point on the curve that is closest to the total head of your system.

3. At that point, take the flow rate directly from the graph.

For instance, if your system has a total head of fifty feet, locate the fifty-foot mark on the pump curve's vertical axis. After that, read the corresponding flow rate on the horizontal axis by tracing horizontally to the point where it intersects the curve.

Method by Affinity Laws:

Estimating how changes in pump speed or impeller diameter affect flow rate, head, and power can be done with the help of affinity laws. These regulations state:

1. Speed 2 has a direct correlation with flow. Speed 3 is inversely proportional to head. For the purpose of calculating flow at a different speed, power is proportional to the speed cube:

For instance, if a pump delivers 100 GPM at 1750 RPM and you want to know the flow at 1450 RPM: New Flow = Original Flow (New Speed / Original Speed).

These methods provide a solid foundation for calculating pump flow: New Flow = 100 GPM = (1450 RPM / 1750 RPM) = 82.9 GPM However, it is essential to keep in mind that variations may be introduced by actual conditions, as we will discuss in the practical considerations section.

Pump Selection and Design

Matching the capabilities of the pump to your system's requirements is the first step in selecting the appropriate submersible axial flow pump. The required flow rate and total head are the most important considerations.

Start by determining the flow rate requirements of your system. This could be based on things like the need for water, the requirements of the process, or the regulations. The total head, which includes both static and dynamic parts, should be determined next.

You can begin the pump selection process with these parameters:

1. Audit siphon indexes or online determination devices from respectable producers.

2. Find pumps with the capacity to deliver the desired flow rate at the estimated total head.

3. To ensure energy-efficient operation, consider the pump's efficiency at your operating point.

4. To avoid problems with cavitation, check the pump's Net Positive Suction Head Required (NPSHR).

In this process, the size and speed of the pump are crucial factors. Although they may be less effective at lower flows, larger pumps typically offer higher flow rates. Higher speeds may result in increased wear and energy consumption, but they may also increase flow and head.

Choosing a pump that operates close to its best efficiency point (BEP) in normal conditions is frequently advantageous. The pump's optimal performance and longevity are guaranteed by this.

Keep in mind that the design of Submersible axial flow pump requires special considerations. The motor must be watertight and able to function underwater. The submersible's additional length and potential vibration issues must be taken into account in the design of the axial.

Practical Considerations

Although theoretical calculations are a good place to start, the actual flow of a submersible axial flow pump in real-world applications can be affected by a number of practical factors.

Properties of a Liquid:

The pump's performance can be significantly impacted by the pumped liquid's density and viscosity. Fluids with a higher viscosity typically decrease efficiency and flow rate while also increasing power consumption. For adjusted performance curves when pumping liquids with significantly different properties than water, consult the pump manufacturer.

Plan of the Pipeline:

The pump's flow rate is influenced by the total dynamic head and, as a result, by the configuration of your piping system. Increased friction losses are caused by long pipe runs, numerous bends, and elevation changes. To accurately determine these losses, make use of software or standard hydraulic calculations.

Fittings and Valves:

Your system's various valves and fittings cause additional friction losses. The length of straight pipe that corresponds to each component can be used to calculate its contribution to the total head. In your calculations, make sure to take these into account.

Wear and tear and Upkeep:

Wear, corrosion, or the accumulation of deposits can all cause a decline in pump performance over time. The pump must be serviced and tested on a regular basis to ensure that it continues to operate at the intended flow rate.

Operation at a Variable Speed:

You can change the flow rate by changing the speed of your pump if it has a variable frequency drive (VFD). This makes operation more adaptable, but choosing the right pump requires careful consideration of the entire operating range.

Curve of System:

The actual operating point is determined by the interaction between the pump curve and the system curve, which represents the head required at various flow rates in your particular system. This point can be shifted by system changes like opening or closing valves.

Factors from the outside:

Performance of submersible pumps can be affected by water temperature and submergence depth. Make sure to account for these in your calculations and pump choice.

You can improve your flow calculations and make more accurate predictions of pump performance under real-world conditions by taking these practical considerations into account.

Submersible axial flow pump manufacturer

Submersible axial flow pumps from Tianjin Kairun Flow Pump are produced in accordance with a number of industry standards and regulations, including ISO 2858. Kairun Flow Pump offers a selection of submersible axial flow pumps for a variety of applications. Our pumps are designed to be effective and dependable in a variety of sectors, including the water supply, wastewater treatment, and industrial processes sectors.

You can get in touch with Tianjin Kairun Flow Pump at catherine@kairunpump.com to learn more about us submersible axial flow pumps or to discuss your specific requirements.

References:

1. Hydraulic Institute. (2010). Pump Life Cycle Costs: A Guide to LCC Analysis for Pumping Systems.

2. Karassik, I. J., Messina, J. P., Cooper, P., & Heald, C. C. (2008). Pump Handbook (4th ed.). McGraw-Hill Education.

3. Grundfos. (2021). The Centrifugal Pump. 

4. KSB. (2021). Selecting Centrifugal Pumps. 

5. Sulzer. (2021). Pump Selection: 5 Steps to Success. 

6. Europump and Hydraulic Institute. (2001). Pump Life Cycle Costs: A Guide to LCC Analysis for Pumping Systems.