Arc gear pump gear running principle

Arc gear pump has three kinds of commonly used gear forms: straight teeth, helical teeth and herringbone teeth. The three forms have their own advantages and disadvantages, have different applications. Straight teeth are the simplest form and are optimally used under high pressure conditions because there is no axial thrust and the delivery efficiency is high. Material selection is high temperature industrial pump selection is very important. Gear pumps are often used to deliver highly corrosive, abrasive or fluid-prone fluids. Pump housing, shaft and bearing material must first match with the pumped liquid. The pump design becomes even more complicated when extra heat is taken into account, even considering the thermal expansions of various materials. Helical teeth have the least amount of pulsation during delivery and are quieter at higher speeds because the meshing of the teeth is gradual. External gear pump operation principle is very simple. The liquid enters the suction side of the pump, is inhaled by the interdental cavities that are not engaged, and is then entrained within the cavities in the interdental space, reaching the exit end along the outer periphery of the gear shaft. The re-engaged tooth pushes the liquid out of the hole into the back pressure. In theory, the nominal displacement of a positive displacement pump is independent of the pressure. However, volumetric failure or internal leakage is inherent to all types of positive displacement pumps. In order to achieve a high pressure differential and the required nominal flow rate, the gear pump must overcome this internal leakage. However, due to the axial thrust, the selection of bearing material may result in limited pressure difference between inlet and outlet and lower viscosity. Because the axial force will push the gear to the bearing face and friction, so only choose the higher hardness of the bearing material or in its end face for special design, in order to cope with this axial thrust. Preheating of the pump is necessary to prevent damage to the components by high temperature shocks. Preheat is recommended when the pumped fluid temperature is above 150 ° C. When using a mechanical seal, the pump must be preheated to within 30 ° C of the operating temperature to prevent damage to the sealing surface. Jacket pump can be steam, heat medium and electric heating to preheat. In order to maximize the capacity of the circular gear pump, the clearance between these mating components must be as small as possible to limit internal leakage. However, just narrowing the gap is not as simple as it sounds. Other factors such as temperature, viscosity, and material selection must also be considered. There is not all internal leakage is a bad thing. In gear pumps, some internal leakage is required to lubricate the internal passages and form a fluid film in the sliding bearings to dynamically support the gear shaft. The correct design should be, the internal leakage is 1 to 3% of the flow.