As a supplier of Peripheral Vane Pumps, I've witnessed firsthand the diverse needs and challenges our customers face when it comes to controlling the flow rate of these pumps. Peripheral Vane Pumps are known for their high head and relatively low flow rate capabilities, making them suitable for a variety of applications such as water supply systems, small - scale irrigation, and industrial fluid transfer. In this blog, I'll share some effective ways to control the flow rate of a Peripheral Vane Pump.
1. Throttle Valve Control
One of the simplest and most commonly used methods for controlling the flow rate of a Peripheral Vane Pump is through the use of a throttle valve. A throttle valve, also known as a flow control valve, is installed in the discharge line of the pump. By adjusting the opening of the valve, we can restrict or allow more fluid to pass through, thereby controlling the flow rate.
When the throttle valve is fully open, the pump can operate at its maximum flow rate. As we gradually close the valve, the resistance in the discharge line increases. According to the pump performance curve, an increase in the system resistance will cause the flow rate to decrease while the head increases. This method is easy to implement and is cost - effective, especially for applications where the flow rate does not need to be adjusted frequently.
However, there are some drawbacks to this method. When the throttle valve is significantly closed, the pump may operate at a point far from its best - efficiency point (BEP). This can lead to increased energy consumption, as the pump has to work harder to overcome the increased resistance. Additionally, excessive throttling can cause cavitation in the pump, which can damage the pump impeller and reduce its service life.
2. Variable Frequency Drive (VFD) Control
A Variable Frequency Drive is an electronic device that can adjust the speed of an electric motor driving the Peripheral Vane Pump. By changing the frequency of the electrical power supplied to the motor, the speed of the motor and thus the pump can be altered.
The flow rate of a pump is directly proportional to its speed. According to the affinity laws, if the speed of the pump is reduced by a certain percentage, the flow rate will decrease by the same percentage. For example, if the pump speed is reduced to 80% of its original speed, the flow rate will also be approximately 80% of the original flow rate. Moreover, the power consumption of the pump is proportional to the cube of the speed. So, a small reduction in speed can lead to a significant reduction in power consumption.
VFD control offers several advantages. It allows for precise control of the flow rate, and the pump can operate closer to its BEP over a wide range of flow rates. This results in energy savings and improved pump efficiency. It also reduces the mechanical stress on the pump and motor, as the soft - start and soft - stop functions of the VFD can prevent sudden load changes.
However, the initial cost of a VFD is relatively high, and it requires proper installation and commissioning. In addition, VFDs generate electrical noise, which may require additional filtering and shielding to prevent interference with other electrical equipment.
3. Bypass Line Control
A bypass line is a pipe that connects the discharge line of the pump to the suction line. By installing a valve in the bypass line, we can divert a portion of the pumped fluid back to the suction side of the pump.
When the valve in the bypass line is opened, some of the fluid that would otherwise flow to the system is redirected back to the pump inlet. This effectively reduces the net flow rate to the system while keeping the pump operating at a relatively constant flow rate. The pump can continue to operate at or near its BEP, which helps to maintain its efficiency.
This method is useful for applications where a constant flow rate through the pump is required, but the flow rate to the system needs to be adjusted. However, it may not be the most energy - efficient method, as the pump is still consuming energy to circulate the fluid through the bypass line.
4. Impeller Trimming
Impeller trimming is a permanent method of adjusting the pump performance. By reducing the diameter of the impeller, the flow rate and head of the pump can be decreased.
The affinity laws also apply to impeller trimming. A reduction in the impeller diameter will cause a decrease in the flow rate, head, and power consumption of the pump. This method is suitable for applications where the required flow rate is significantly lower than the pump's original design flow rate and where a long - term, fixed - flow - rate adjustment is needed.
However, impeller trimming is a one - time adjustment. Once the impeller is trimmed, it cannot be easily restored to its original size. Therefore, it requires careful calculation and consideration before implementation.
5. Parallel and Series Pump Operation
In some cases, using multiple Peripheral Vane Pumps in parallel or series can also help to control the flow rate.
When pumps are operated in parallel, the total flow rate is the sum of the flow rates of individual pumps at the same head. This is useful when a higher flow rate is required for a short period. By starting or stopping one or more pumps in the parallel arrangement, the total flow rate can be adjusted.
On the other hand, when pumps are operated in series, the total head is the sum of the heads of individual pumps at the same flow rate. This is suitable for applications where a higher head is needed. Although series operation is not primarily used for flow - rate control, it can be combined with other methods to achieve the desired system performance.
Conclusion
Controlling the flow rate of a Peripheral Vane Pump is crucial for ensuring the efficient and reliable operation of the pumping system. Each of the methods mentioned above has its own advantages and disadvantages, and the choice of the method depends on various factors such as the application requirements, cost, energy efficiency, and frequency of flow - rate adjustment.
As a supplier of Peripheral Vane Pumps, we offer a wide range of products, including Peripheral Booster Pump, Self - priming Peripheral Pumps, and Intelligent Peripheral Pumps. Our team of experts can provide you with professional advice on the best flow - rate control solution for your specific needs.
If you are interested in our products or need more information on pump flow - rate control, please feel free to contact us for procurement and further discussions. We are committed to providing you with high - quality products and excellent service.
References
- Karassik, I. J., Messina, J. P., Cooper, P. T., & Heald, C. C. (2008). Pump Handbook. McGraw - Hill.
- Stepanoff, A. J. (1957). Centrifugal and Axial Flow Pumps: Theory, Design, and Application. John Wiley & Sons.