Various criteria for the life of mechanical seals

<p>Various criteria for the life of <a href="https://www.lepuseal.com/products-1" target="_blank">mechanical seals</a></p><p><br></p><p>Because the life of <a href="https://www.lepuseal.com/products-1" rel="noopener noreferrer" target="_blank"><strong>mechanical seals</strong></a> is directly related to the performance and efficiency of equipment, we need to introduce and understand the various criteria for the life of their accessories.</p><p>It is well known that mechanical seals are one of the basic mechanical components with fine, dense and complex structure. They are the key components of various pumps, reaction synthesis kettles, turbo compressors, submersible motors and other equipment. Its sealing performance and service life depend on many factors, such as type selection, machine accuracy, correct installation and use, etc.</p><p><br></p><p>According to the different working conditions and the nature of the medium, there are high temperature and low temperature resistant seals, high pressure resistant, corrosion resistant seals, particle resistant medium seals and seals suitable for light hydrocarbon media that are easy to vaporize, etc., according to different uses Choose seals of different structural types and materials.</p><p>The main parameters of the selection are: sealed cavity pressure (MPA), fluid temperature (℃), working speed (M/S), fluid characteristics, and effective space for installation and sealing.</p><p><br></p><p>The basic principle of selection is:</p><p>1: According to the pressure of the sealed cavity, it is determined that the sealing structure adopts balanced or unbalanced, single end face or double end face, etc.</p><p>2: According to the working speed, determine the use of rotary or static, fluid dynamic pressure or non-contact type.</p><p>3: According to the temperature and fluid properties, determine the friction pair and auxiliary sealing materials, and correctly select the lubrication, flushing, heat preservation, cooling and other seal circulation protection systems.</p><p>4: According to the effective space of the installation seal, it is determined to use multiple springs or single springs or wave springs, built-in or exterior-mounted.</p><p><br></p><p>Various criteria for the life of mechanical seals</p><p><br></p><p>2. Installation and use requirements</p><p>1: Requirements for machine accuracy (take pump as an example)</p><p>(1) The radial runout tolerance of the shaft (or sleeve) where the seal is installed does not exceed 0:04~0:06MM.</p><p>(2) The axial movement of the rotor does not exceed 0: 3MM.</p><p>(3) The runout tolerance of the positioning end facing the shaft (or sleeve) surface of the sealing cavity and the sealing end cover shall not exceed 0:04～0:06MM.</p><p>2: Confirmation of seals</p><p>(1) Confirm whether the installed seal is consistent with the required model.</p><p>(2) Check carefully with the final assembly drawing before installation, and check whether the number of parts is complete.</p><p>(3) The mechanical seal is driven by a parallel spring. The spring can be divided into left and right rotation, which must be selected according to the rotation direction of the shaft.</p><p>3: The installation method varies with the type of seal and the type of machine, but the installation essentials are almost the same. The installation steps and precautions are as follows:</p><p>(1) When installing the mechanical seal, the installation dimensions should be guaranteed according to the product's instruction manual or sample.</p><p>(2) Before installation, the shaft (sleeve) and gland should be free of burrs, and the bearing should be in good condition; the seals, shaft, seal cavity, and gland should all be cleaned. In order to reduce frictional resistance, the part where the seal is installed on the shaft should be coated with a thin layer of oil for lubrication. Taking into account the compatibility of the rubber O-ring, if it is not suitable to use oil, it can be coated with soapy water. The floating static ring has no anti-rotation pin structure, so it is not suitable to be oiled and should be dry-mounted in the gland.</p><p>(3) First install the static ring and gland on the shaft, taking care not to collide with 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.</p><p>(4) Before the gland is fixed, push the compensation ring by hand to compress it axially. After loosening, the compensation ring can automatically spring back without jamming, and then evenly lock the gland bolts.</p><p>4: Use</p><p>(1) When the temperature of the conveying medium is too high, too low, or contains impurity particles, is flammable, explosive, or toxic, corresponding measures such as sealing, washing, cooling, and filtering must be taken.</p><p>(2) Before running, turn the wheel by hand, pay attention to whether the torque is too large, whether there is rubbing or abnormal sound.</p><p>(3) Pay attention to the direction of rotation, whether the coupling is centered, whether the lubricating oil at the bearing part is added properly, and whether the piping is correct.</p><p>(4) Before operation, first open the medium and cooling water valve, check whether the gas in the sealed cavity is completely discharged to prevent leakage caused by static pressure, and then start the operation.</p><p>(5) Whether the work is normal and stable after driving, whether there is abnormal torque caused by shaft rotation, abnormal noise and overheating.</p>