In many industrial production and daily life application scenarios, pumps play a vital role. In order to make the pump serve us better, we must have a deep understanding of the two key elements of the pump-flow and head. Next, let’s explore them together.
What is Pump Flow Rate?
The flow of the pump, in simple terms, refers to the amount of fluid that the pump can deliver per unit time. For example, it’s like you use a bucket to collect water. If you can fill a bucket of water in one minute, then the amount of “one bucket of water per minute” is similar to the concept of pump flow. It’s just that the amount delivered by the pump is usually measured in professional units such as cubic meters per hour and liters per second.
The size of the flow rate has a great impact on the application scenario of the pump. For example, in farmland irrigation, a pump with a large flow rate can irrigate a large area of farmland in a short time, so that crops can get enough water in time.
There are also many factors that affect the pump flow rate. From the design of the pump itself, the characteristics of the impeller are critical. The diameter of the impeller, the number of blades, and the angle will affect how much fluid can be pushed forward each time it rotates. In addition, the speed of the pump, the resistance of the system, the viscosity of the fluid, etc. will affect the flow rate of the pump.
What is Pump Head?
The pump head is actually the height to which the pump can lift the fluid. Or it can overcome the resistance of the pipeline and other factors to allow the fluid to flow. Imagine that we want to pump water from the pool on the first floor to the water tank on the second floor. The height to which the water is lifted is part of the head.
However, the head is not just a simple vertical height, but also includes the “strength” required to overcome various resistances in the pipeline.
There are different types of heads. For example, the suction head is the pressure that the pump needs to overcome before the fluid enters the pump to allow the fluid to enter. The discharge head is the height corresponding to the ability of the pump to continue to flow forward and overcome subsequent resistance after the fluid comes out of the pump. The total head is the value obtained by subtracting the suction head from the discharge head.
There is also the concept of closed head, which is the maximum head that the pump can generate when the pump outlet valve is closed. That is, when there is no fluid being transported out, this can reflect the performance of the pump itself from the side.
The Relationship Between Flow Rate and Head
Flow and head are like a pair of good partners, influencing and restricting each other. Generally speaking, in the performance curve of the pump, as the head increases, the flow tends to decrease.
For a given pump, its design determines the general change law between flow and head. For example, some pumps focus on high head and small flow conditions. It is suitable for conveying fluids to a relatively high position. But the amount of delivery is not large. Like the water supply system of some high-rise buildings, water needs to be delivered to dozens of floors high. Such pumps will be selected.
Some pumps have large flow and low head. It is suitable for conveying a large amount of fluid in a short distance. Like some large-area cooling circulating water systems in factories. This type of pump is mainly used to quickly convey a large amount of water on a plane.
How to Select a Pump Based on Flow Rate and Head
When choosing a pump, flow rate and head are key considerations.
First, it is necessary to clarify how much flow rate is required for the actual use scenario. For example, if you want to irrigate an orchard of a certain area, you need to know how many cubic meters of water you need to deliver per hour. At the same time, it is also necessary to know how much head you need to overcome. Whether you pump the water to a high mountain orchard, or just let the water flow a certain distance on the flat ground, etc., all need to be considered.
Then, you have to make a comprehensive judgment based on the situation of the entire system. If the pipes in the system are longer and there are more pipe fittings and valves. That means there is a lot of resistance. You have to choose a pump with a slightly higher head, otherwise the water may not be delivered to the desired place. In addition, the properties of the fluid cannot be ignored. If the liquid being transported is a more viscous liquid, then under the same flow rate and head requirements. You may have to choose a pump with a higher power to ensure normal delivery. If you don’t know how to choose the right pump for your project, please contact us.
Common Issues and Troubleshooting
Problems with flow
Sometimes the flow is insufficient, which may be due to the wear of the impeller. At this time, you have to check the impeller to see if it needs to be replaced. It may also be that the suction pipe is blocked and the fluid cannot enter, so the flow is naturally small. Then you need to check the suction pipe and clean up the blocked debris.
In addition, if cavitation occurs in the system. That is, the liquid in the pump becomes gas and then turns back to liquid due to pressure changes, and bubbles are generated to impact the impeller and other components. It will also affect the flow. At this time, you have to adjust the system pressure, improve the suction conditions, etc. to prevent cavitation.
Problems with head
If you find that the head is not enough, the water cannot be sent to where it should go. It may be that the speed of the pump has not reached the rated value. Then you have to check the power equipment such as the motor to see if there is a fault.
It may also be that the resistance of the pipeline is much greater than expected. This requires re-examining the design and installation of the pipeline to see if the pipe diameter is too small or there are too many elbows. If necessary, the pipeline must be modified to reduce the resistance. There may also be a performance decline in the pump itself. For example, poor sealing leads to pressure leakage. At this time, the sealing parts of the pump must be repaired or replaced.
Conclusion
The flow rate and head of the pump are two very critical indicators in the operation of the pump. They affect whether the pump can efficiently and accurately complete the fluid delivery task in various application scenarios. Understand their respective meanings, relationships, and key points in selecting pumps and troubleshooting. It is of great significance for us to use and maintain the pump well.
In actual production and life, whether it is a large industrial project or a small household water use scene. We need to accurately grasp the two key factors of flow rate and head according to the specific situation, so that the pump can serve us better.
