\nWhile they are not a household name, rotary vane pumps play a critical role in everyday life. Whether it be transporting power steering fluid in a car, helping a fountain drink contain the perfect amount of carbonation, or transporting thick liquids without damaging their quality, rotary vane pumps undoubtedly perform a substantial role in the products you enjoy. Below you can find information about what rotary vane pumps are, how they work, their advantages and disadvantages, and the different types of vane pumps.\nWhat is a rotary vane pump?\nA rotary vane pump, also known as a vacuum pump, is a self-priming positive displacement pump that moves fluids and gasses with vanes mounted to a rotor inside a cylindrical housing. The liquids and gasses are compressed, pressurized, and passed through the pump outlet. Automobile manufacturers use vacuum pumps in numerous applications, such as power steering, air conditioning, and automatic transmissions. The food and beverage industry also uses rotary vane pumps for fountain drink dispensers, espresso machines, and the transportation of viscous liquids. They are also commonly used in the water treatment industry for feeding pressurized water to reverse osmosis filtration membranes.\nPositive displacement vs centrifugal pumps\nAs previously stated, a rotary vane pump is a positive displacement pump. Positive displacement pumps work by capturing a predetermined volume of liquid and moving it between the suction and discharge chambers. The seals created by the vanes and the flow of liquids create pressure. Positive displacement pumps can sustain high pressures while utilizing low suction pressure, and they are not affected by the fluid’s incoming pressure. In contrast, centrifugal pumps create initial pressure that results in flow.\nPositive displacement pumps can pump liquids with a higher viscosity than centrifugal pumps can. This is a result of frictional losses inside centrifugal pumps. On the other hand, positive displacement pumps increase efficiency with higher viscosity liquids to a certain point.\n\nHow does a rotary vane pump work?\nRotary vane pumps contain two or more chambers that compress, rotate, and discharge gasses and liquids. These chambers create a vacuum that pressurizes the contents, allowing them to travel through the pump’s outlet. The vanes slide in and out and turn against the inner wall of the rotor. As the vanes rotate, one chamber forms, and the outlet valve divides the chamber into suction and discharge sides. The fluid enters the suction side of the chamber, where it compresses with each rotation. Once the suction chamber reaches its maximum capacity, the contents release into the discharge chamber and through the pump outlet. Finally, an exhaust valve prevents backflow by blocking contents that try to reenter the pump.\nWhat are rotary vane pumps used for?\nHigh-pressure vacuum pumps are commonly used for transporting freon, power-steering fluid, and transmission fluid in automobiles. On the other hand, medium-pressure pumps transport water in espresso machines and carbonated beverage dispensers. While less common than higher pressure pumps, low-pressure rotary vane pumps are used in chemical vapor deposition, a method used to create thin film for semiconductors. Other uses for vacuum pumps include:\n\nDust extraction systems\nIndustrial furnaces\nVacuum filtration\nDegassing\nCrystallization\nDistillation drying\n\nParts of a rotary vane pump\nThe major components of a rotary vane pump are the following:\n\nRotor\nStator\nVanes (also called blades)\nCylindrical housing\nInlet\nExhaust valve\nExhaust outlet\nOil reservoir\nSplash guard\n\n\nTypes of rotary vane pumps\nRotary vane pumps generally perform the same function, but they can have many different types of vanes. These vane types include:\n\nSliding – vanes slide in and out to draw liquid in through the inlet port and into the chamber\nFlexible – vanes maintain contact with the rotor walls, trapping liquid as the vanes rotate\nExternal – vanes are fitted into the pump’s casing instead of the rotor\nRotating – vanes rotate inside the cavity to trap liquids\nOscillating – vanes draw in liquids with an oscillating pumping motion\n\nSliding and flexible vane pumps are the most common type of rotary vane pump and are used in various commercial applications. Sliding vane pumps are commonly found near fountain drink dispensers and espresso machines. They transport water into pressurized CO2 tanks and pass heated water through espresso grinds. On the other hand, flexible vane pumps are commonly used in food and pharmaceutical applications. They are effective at transporting viscous liquids, such as creams, and liquids with solids, such as yogurt, without compromising the quality of the product.\nOil-lubricated vs dry-running rotary vane pumps\nDry-running and oil-lubricated work very similarly, but oil decreases wear on the pump and enhances the seals formed in the rotor.\nOil-lubricated rotary vane pump operation\nOil-lubricated vane pumps operate like dry vane pumps with a few key differences. They cannot be used in the water treatment industry because of their residual effects on the discharge.\n\nAn oil pipe feeds the cylindrical housing oil, where it coats the vanes and walls to prevent wear.\nThe vanes push against the rotor walls, forming chambers that capture air and liquid.\nThe captured air and fluid are compressed and transported to a compression chamber.\nWhen the chamber reaches its maximum compression, it opens and discharges into the oil separator housing\nThe oil separator housing removes oil particles from the air or liquid.\nFurther filtration removes leftover oil particles.\nThe air or liquid is discharged through the outlet.\n\nDry rotary vane pump operation\nDry vane pumps operate like oil-lubricated vane pumps with a few key differences.\n\nDry-running pumps use graphite vanes that contact the inner walls of the rotor. The graphite coats the walls, allowing the vanes to contact them with minimal wear.\nWhen liquid enters, the vanes trap the liquid in the chamber, where it is compressed, rotated, and discharged.\nExcess air is discharged after the fluid is compressed.\nUnlike oil-lubricated vane pumps, dry-running pumps do not need any post-filtration because nothing has been added to the air or liquid.\n\nDo rotary vane pumps need oil?\nOil is a helpful addition to a rotary vane pump in some cases, but it is not ideal for every application. Oil performs four essential functions in a vane pump:\n\nSeals between the rotor and vanes\nForms a second seal between vanes and chamber\nCools the pump by dispersing heat\nProtects components from corrosion\n\nOil provides seals that make vacuum pumps far more efficient than dry-running ones. However, oil can exit with pressurized gasses in a pump, making it unsuitable for some applications. Oil traps help mitigate oil expulsion, but pumps will always expel oil regardless of how high-quality the oil trap is.\nBenefits of oil in a rotary vane pump\nWhile rotary vane pumps can run completely dry, some units benefit from the lubrication oil provides. The following are benefits oil has on a rotary vane pump:\n\n\nProvides a seal that enhances the ability to form a vacuum\n\nElongates the life of a pump by preventing wear\n\nKeeps temperatures cool by reducing friction\n\nEliminates impurities and prevents them from damaging the pump\n\nPrevents pump from corrosion caused by reacting with gas\n\nIncreases the efficiency of the pump by creating more effective seals\n\n \nAdvantages of rotary vane pumps\nRotary vane pumps have many advantages regardless of the types of vanes inside them.\n\nExtended lifespan due to durable vanes\nQuiet operation\nLittle vibration\nLow maintenance\nCan run completely dry\nLightweight and compact\nDischarged liquid is not sensitive to viscosity changes\nStable flow rate with low pulsation\n\nDisadvantages of rotary vane pumps\nRotary vane pumps are excellent at transporting liquids, but their operation does pose some risks and disadvantages.\n\nPoor durability when in contact with abrasive materials\nProne to damage when operating with thicker liquids\nProper filtration systems needed before adding liquids to the pump\nNot suitable for very high pressures\n\n\n\n \nIf you have any further questions about rotary vane pumps, please do not hesitate to contact us.