This small flow does not pass between the gears.

Liquid could also travel around the interior of the casing in the pockets between the teeth and the casing. Liquid flows into the gear teeth cavity and is trapped by the gear teeth as they rotate. Design & OperationДЄs the gears come out of mesh, they create expanding volume on the suction side of a gear pump. The gear pump is simple and consists of a few components, leading to low manufacturing and operating costs.Д®mploying an appropriate combination of self-lubricating materials, a gear pump can be safely operated even when gas bubbles are trapped in the flow subsequent to cavitation phenomena. Various pressure compensation measures and characteristics of gear pumps can offer desirable differential pressure and flow characteristics curve for many applications, and gear pumps can also offer high efficiencies for many targeted services. The gear pump principle features low-pressure pulsations due to the large number of tooth gaps conveying the fluid, which leads to excellent suction behavior and helps prevent cavitation. Among positive displacement pumps, gear pumps possess some vital advantages. In addition to these theoretical concepts of efficiencies and suitability of pressure ranges, other important benefits such as reliability, availability, overall performance and operation should be respected. To aid the selection and design of pumps, different charts and tables have been developed to illustrate the efficiencies and performance of various pump types as a function of the specific speed and other parameters. In general, a specific pump can be operated efficiently for one application but might be inappropriate for others. General Notes on Gear UnitsДuring the past few decades, a large number of pump concepts have emerged, and the selection of an appropriate pump for a specific viscous liquid application has become a major consideration. Because of this, gear pumps might be employed for some precise transfer and metering applications. Tighter internal clearances provide for a reliable measure of liquid passing through a pump and for greater flow control. With bearings in the liquid and tight tolerances, gear pumps are not usually well suited to handle abrasive or extremely high temperature applications.

This allows them to run to pressures beyond 200 bar gauge (Barg), making them well suited for use in high-pressure applications. Gear pumps have close tolerances and shaft support, usually on both sides of the gears. Volumetric efficiencies of gear pumps run as high as 91 percent. As the teeth mesh at the discharge end, the fluid is forced out. A partial vacuum is created at the pump suction fluid flows in to fill the space and is carried around the discharge of the gears. The chambers formed between adjacent gear teeth are enclosed by the pump housing and side plates, also called wear or pressure plates. Small gear pumps usually operate at a speed between 1,700 rpm and 4,500 rpm, and larger models most often operate at speeds below 1,000 rpm.ДЄ gear pump produces flow by carrying fluid between the teeth of two meshing gears. Gear pumps are the most popular type of positive displacement pump. Gear pumps are often used in pumping relatively viscous liquids, such as some viscous liquid hydrocarbons, liquid fuels, lubrication oil pumping in machinery packages, hydraulic units and fluid power transfer units.

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