A volumetric pump is a device that realizes fluid conveying by periodically changing the volume of the pump cavity. Common types include gear pumps, sliding plate pumps, diaphragm pumps, ordinary screw pumps, etc. Although their core logic is volumetric change, the progressive cavity pump, with its continuous and smooth spiral cavity design, is significantly different from the same pump in terms of flow characteristics, media adaptability, anti-blocking ability and operating stability. This article will compare from the five core dimensions and analyze the unique advantages of progressive cavity pumps.
The flow rate of volumetric pumps is essentially the result of periodic suction and discharge, but the flow rate fluctuation of different pump types varies greatly.
The core of the progressive cavity pump is a continuous spiral cavity formed by a spiral rotor and a stator. When the rotor rotates, the cavity moves uniformly along the axis, and the fluid is wrapped in the cavity from the intake end to the discharge end, and there is no sudden volume mutation in the whole process. Therefore, its flow rate changes linearly with the rotational speed, and the pulsation rate can be as low as 1%-3%. Stable flow output can avoid pressure fluctuations. This stability makes it perform well in precision hydraulic systems and improve machining accuracy. The pulsation rate of other volumetric pumps is higher than 5%, It is only applicable to scenarios with low stability requirements.
Fluid complexes in sewage treatment, chemical industry, food and other fields contain mostly particles, fibers, high viscosity or corrosive substances. Traditional volumetric pumps are often unable to adapt to all media due to structural limitations, and the open spiral cavity of the progressive cavity pump breaks this limitation.
The core advantage of its spiral cavity is that there is no narrow channel and elastic stator buffer:
• The channel width can reach 30%-50% of the pump caliber, and can directly convey solid particles with a diameter of ≤8mm;
• The stator is made of elastic rubber. When the particles pass through, the stator will slightly deform the wrapping particles to avoid jamming;
• The viscosity of the medium has a wide range of adaptation, and the efficiency of high-viscosity fluids is only reduced by 5%-10%.
Other volumetric pumps have limitations on the medium:
• Gear pump: Relying on gear gap sealing, it can only convey particle-free, low-viscosity liquids, and particle-containing media will accelerate gear wear;
• Sliding plate pump: The gap between the sliding plate and the stator is small, and the fiber or large particles are easy to get stuck in the gap, resulting in the slipper stuck;
• Diaphragm pump: transported through the reciprocating movement of the diaphragm, the valve ball/valve seat needs to be installed in the channel, and the particles are easy to block the valve, which is only suitable for conveying clean or microparticulate fluids.
Fibers, hair, silt, etc. in the pipe are easy to accumulate in the channel or gap, causing the blockage to make the pump unable to work. The dead-angle-free spiral cavity of the progressive cavity pump completely solves this problem.
Its spiral cavity is a continuous and open space without any dead corners and narrow gaps; after the fluid enters from the suction end, it moves along the spiral groove to the discharge end, and there is no sudden channel contraction or turning throughout the whole process; even if the sewage containing long fibers is transported, the fibers will be wrapped in the spiral cavity and translated with the fluid, and will not be wrapped or blocked.
Other volumetric pumps: structural defects in hiding dirt and scale
• Gear pump: The gap between the gear and the pump body is small, and the fiber is easily stuck in the gap, causing the gear to be stuck;
• Sliding plate pump: The contact surface of the sliding plate and the stator is line contact, and small particles are easy to be embedded in the contact surface, resulting in the sliding plate blocking;
• Diaphragm pump: The valve ball/seat is a particle trap, and tiny particles will be stuck in the valve, resulting in poor suction.
For the back-end process, the stability of the flow directly affects the processing effect and cost. The low pulsation and constant flow characteristics of the progressive cavity pump make it a stabilizer for precision processes.
Its flow rate is only determined by the rotational speed, and the pulsation rate is extremely low, which can achieve precise flow adjustment:
• When equipped with a frequency converter motor, the rotational speed can be adjusted steplessly within the rated speed range, and the flow rate will change linearly;
• In the sludge dehydration link, the stable sludge flow can ensure that the conditioner and sludge are fully mixed and improve the dehydration efficiency;
• In the agent addition system, the constant flow output avoids secondary pollution or agent waste caused by excessive addition.
Other volumetric pumps have large and small flow problems:
• Gear pump: the flow pulsation is large, and an additional buffer tank needs to be configured to stabilize the flow and increase the complexity of the system;
• Sliding plate pump: the pulsation rate is about 5%-10%. Although it is better than the gear pump, it still needs a buffer device;
• Diaphragm pump: The flow rate is affected by the opening and closing frequency of the valve, which is only suitable for scenarios with low requirements for flow accuracy b;
The maintenance cost of volumetric pumps often accounts for 30%-50% of the total operating cost, and the modularization and low-wear design of progressive cavity pumps greatly reduce this burden.
Its core parts are only rotors, stators and seals, and there is no complex transmission mechanism
• The stator is an independent module. When replacing, you only need to remove the pump body flange and pull out the rotor to complete it;
• The surface of the rotor is hardened, and the stator is an elastomer. When transporting sand-containing sewage, the service life can be up to 2-3 years.
Other volumetric pumps require high cost of repair and maintenance:
• Gear pump: It takes 2-4 hours to remove the pump body, replace the gear and sealing ring, and the gears are easy to wear out;
• Slipper pump: the slipper and stator need to be replaced as a whole, and the maintenance cost is high;
• Diaphragm pump: The diaphragm and valve ball need to be replaced frequently, and the valve seat is prone to wear and leakage.
Compared with other volumetric pumps, the core advantage of the progressive cavity pump comes from the unique design of its continuous spiral cavity. It solves the pain points of flow pulsation, media adaptability, anti-blockage, operation stability and so on through progressive volumetric migration, and becomes an all-rounder for conveying complex fluids. In the fields of sewage treatment, chemical industry, food and medicine, its comprehensive performance is significantly superior to that of traditional volumetric pumps, and it is an invisible champion in the field of industrial fluid conveying.
Teffiko focuses on the research and development, production and sales of progressive cavity pumps. Due to its deep technical accumulation and innovative spirit, these products enjoy a good reputation in the pump industry. The company has a professional research and development team, advanced production equipment and a strict quality inspection system. We are committed to improving their performance, providing high-quality products to global customers, and meeting the fluid conveying needs of various industries.
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