Comparison of flow rates between centrifugal pumps and positive displacement pumps
The flow range of centrifugal pumps is usually large, and the flow regulation methods are flexible and diverse, which is suitable for large flow and high head occasions; while the flow range of volumetric pumps is relatively small, and the flow stability is good, which is suitable for small flow and occasions that require precise flow control. The flow size comparison of centrifugal pumps and volumetric pumps can be carried out from the following aspects:
1. Flow range:
Centrifugal pumps: The flow range of centrifugal pumps is usually large, and the flow can be adjusted according to demand by adjusting parameters such as speed and impeller diameter. For example, the flow range of some high-efficiency single-stage double-suction centrifugal pumps can reach 9000~46000m³/h (reference article 4).
Volumetric pumps: The flow range of volumetric pumps is relatively small, especially the flow increase achieved by parallel connection is relatively limited. For example, the volumetric pump can only reach 200L/S through parallel connection (reference article 3), which is much smaller than the flow range of centrifugal pumps.
2. Flow regulation method:
Centrifugal pumps: The flow is mainly adjusted by adjusting the speed, impeller design, inlet and outlet valves, etc. For example, increasing the speed can increase the flow, and reducing the speed can reduce the flow (reference article 1).
Positive displacement pump: Flow regulation is mainly achieved by changing the pump speed, cavity volume or using hydraulic control valves, hydraulic cylinders and connecting rods.
3. Flow stability:
Centrifugal pump: Within the appropriate flow range, the flow stability of the centrifugal pump is good. However, if the flow is too large or too small, it may affect the performance and life of the pump.
Positive displacement pump: The flow stability of the positive displacement pump is relatively high, because its flow is mainly determined by the cavity volume and speed of the pump, and is less affected by external conditions.
4. Application scenarios:
Centrifugal pump: Suitable for occasions with large flow and high head, such as water supply, drainage, chemical production, etc.
Positive displacement pump: Suitable for occasions with small flow and precise flow control, such as metering pumps in the petroleum, chemical, food and other industries.
