நேர்மறை இடப்பெயர்ச்சி விசையியக்கக் குழாய்கள் மற்றும் மையவிலக்கு விசையியக்கக் குழாய்கள்

Positive displacement pumps and centrifugal pumps are two common types of pumps. They have some differences in working principles, performance characteristics, and application scenarios. Next, I will specifically introduce what these differences are.

Working Principles

• Positive Displacement Pumps: Positive displacement pumps rely on the periodic change of the working volume caused by the movement of working components to transport liquids. When the working volume increases, a low - pressure area is formed to suck in the liquid. When the working volume decreases, the liquid is squeezed to increase its pressure and then discharged. The working components move periodically and reciprocally to continuously achieve the suction and discharge of the liquid. This makes the flow rate stable, enables the generation of high pressure, and is suitable for transporting high - viscosity fluids.
• Centrifugal Pumps: Centrifugal pumps use the centrifugal force generated by the rotation of the impeller to impart energy to the liquid. When the impeller rotates at a high speed, the liquid is thrown to the outer edge of the impeller under the action of centrifugal force, creating a low - pressure area at the center of the impeller. The outside liquid enters the pump under the action of atmospheric pressure and is continuously thrown out and transported by the impeller.

Performance Characteristics

• Flow Rate: The flow rate of positive displacement pumps is directly proportional to the rotational speed. When the rotational speed is constant, the flow rate is basically constant and is not affected by pressure changes. The flow rate of centrifugal pumps is related to factors such as rotational speed and impeller diameter, and the flow rate changes with the change of head (pressure). Generally, as the head increases, the flow rate decreases accordingly.
• Pressure: Positive displacement pumps can generate relatively high pressure. Theoretically, they can reach an infinitely high pressure as long as the pump structure and materials can withstand it. The pressure - increasing capacity of centrifugal pumps is relatively limited. Their maximum pressure depends on factors such as the diameter of the impeller, rotational speed, and pump structure.
• Efficiency: Positive displacement pumps have higher efficiency under low - flow - rate and high - pressure conditions, but their efficiency may be low under high - flow - rate and low - pressure conditions. Centrifugal pumps have higher efficiency near the designed operating point. When the flow rate deviates from the design value, the efficiency drops significantly.
• Self - Priming Ability: Most positive displacement pumps have good self - priming ability and can automatically suck in liquid when starting. Centrifugal pumps generally have poor self - priming ability and usually need to be primed before starting to expel the air inside the pump and prevent air - binding.

Application Scenarios

• Positive Displacement Pumps: They are suitable for situations with high viscosity, low flow rate, and high pressure, such as transporting high - viscosity crude oil and lubricating oil in the petrochemical industry. They are also often used in systems that require accurate flow measurement, such as metering pumps.
• Centrifugal Pumps: They are widely used in situations with large flow rates and relatively low heads, such as urban water supply and drainage systems, agricultural irrigation, and transporting liquids of general viscosity in chemical processes.

When selecting a pump, it is necessary to comprehensively consider factors such as specific process requirements, fluid characteristics, and system operating conditions to determine the most suitable pump type. If you still have questions about pump selection, TEFFIKO welcomes you to contact us. We have a professional technical team and rich experience to help you develop a perfect solution.