Selection and equipment of mechanical seals for oil pumps

Selection and equipment of mechanical seals for oil pumps

The oil pump mechanical seal is one of the basic mechanical components with precise and complex structure. Its sealing performance and service life depend on many factors, such as model selection, machine accuracy, and precise equipment use. 1. Selection method of oil pump mechanical seals According to the working conditions and the properties of mechanical seals for medium kettles, oil pump mechanical seals include high temperature resistant, low temperature resistant mechanical seals, high pressure and corrosion resistant mechanical seals, and particle medium resistant mechanical seals. Mechanical seals with different structural types and materials should be selected according to different uses. The basic principles of selection are: 1. According to the pressure of the sealing cavity, determine whether the sealing structure should be balanced or unbalanced, single-end or double-end, etc. 2. According to the working speed, it is determined to choose the rotary type or the suspension type, the fluid dynamic pressure type or the non-contact type. 3. According to the temperature and fluid properties, determine the resistance pair and auxiliary sealing materials, and accurately select the lubrication, flushing, heat preservation, cooling and other mechanical seal circulation protection systems. 4. According to the useful space of the equipment seal, it is determined to choose multiple springs or single springs or wave springs, built-in or external. The main parameters for selection are: sealed cavity pressure (MPA), fluid temperature (°C), working speed (M/S), fluid characteristics and useful space for equipment sealing. Second, the equipment and application requirements of the mechanical seal of the oil pump 1. The requirements of the mechanical seal on the machine accuracy (taking the pump mechanical seal as an example) (1) The radial runout tolerance of the shaft (or shaft sleeve) of the mechanical seal part of the equipment should not exceed the maximum 0.04～0.06MM. (2) The axial movement of the rotor does not exceed 0.3MM. (3) The runout tolerance of the positioning end of the sealing cavity and the sealing end cover facing the surface of the shaft (or shaft sleeve) should not exceed 0.04-0.06MM at most. 2. Confirmation of seals (1) Confirm whether the seal of the equipment is the same as the requested type. (2) Carefully check with the general assembly drawing before the equipment to see if the number of parts is complete. (3) Select a mechanical seal driven by a parallel spring, and its springs can be divided into left and right rotations, which must be selected according to the rotation direction of the rotating shaft. 3. The equipment method varies with the type of mechanical seal and the type of machine, but the equipment essentials are almost the same. The equipment process and precautions are as follows: (1) When judging equipment according to the equipment standard, it should be based on the commodity Use instructions or samples to ensure equipment standards for mechanical seals. (2) Before loading, the shaft (sleeve) and gland should be free of burrs, and the bearing should be in good condition; the seals, shaft, sealing cavity and gland should be cleaned. In order to reduce the resistance, the mechanical seal parts of the shaft equipment should be coated with a thin layer of oil for lubrication. Considering the compatibility of rubber O-rings, if oil is not suitable, soapy water can be applied. The structure of floating static ring without anti-rotation pin should not be oiled, and should be installed in the gland dry. (3) Install the static ring together with the gland on the shaft first, being careful not to touch the shaft, and then install the moving ring assembly. The set screws of the spring seat or transmission seat should be tightened evenly in several times. Before the gland is not fixed, the compensation ring should be pushed by hand for axial tightening. After loosening, the compensation ring can automatically spring back without jamming. The cover bolts are tightened evenly.