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Service life and reliability of mechanical seals
by：Lepu Seal
2022-09-15
Service life and reliability of mechanical seals
1. Service life of mechanical seals Mechanical seals rarely fail due to long-term wear, and other factors can often cause their premature failure. Therefore, the life of the seal should be regarded as a statistical quantity, and it is difficult to obtain an accurate value. For example, the mechanical seals used in some sewage pumps generally use hard ring-to-hard ring end face mechanical seals. For example, at a certain period of time, the pump shaft moves in series and the shaft vibrates. At this time, if hard small particles enter the mechanical seal The end face of the seal will wear the end face. The effective working time of the seal depends to a large extent on the application. To prolong the service life of the seal, the following points should be paid attention to: 1. Establish a suitable working environment in the seal cavity, such as effectively controlling the temperature of mechanical seals; removing solid abrasive particles; controlling the rapid fluctuations in pressure and temperature; forming between the seal faces Effective liquid film (double seal and sealing liquid if necessary). 2. The technical specifications of sealing can meet the requirements. 3. The rigidity and manufacturing precision of the pump are high. Considering the service life of the seal, not only the one-time investment of the pump (and seal), but also the economic loss caused by the failure of the seal, including: product loss; investment in backup equipment; and damage to equipment; man-hours and spare parts required to replace the seal, etc. The life limit of seals can vary widely, from just a few days in chemically aggressive conditions to 20 years of effective operation in olefin applications. 2. Reliability of mechanical seals In addition to the above-mentioned different working conditions, the service life of the seal will be greatly different, and the service life of the same seal will also be significantly different under the same conditions of use. This is similar to the test done with rolling bearings. Therefore, statistical concepts are applied when discussing seal reliability. We use the following two values to count the reliability of the seal: 1. L10 life The operating time when the number of failures in a sampled array of parts reaches 10% is called the L10 life. 2. Mean working life (MTBF) The mean working time is defined as the arithmetic mean of the interval time of sampling failures in sequence, MTBF=(L1+L2+??+Ln)/n where L1, L2——the working life of a single seal.
1. Service life of mechanical seals Mechanical seals rarely fail due to long-term wear, and other factors can often cause their premature failure. Therefore, the life of the seal should be regarded as a statistical quantity, and it is difficult to obtain an accurate value. For example, the mechanical seals used in some sewage pumps generally use hard ring-to-hard ring end face mechanical seals. For example, at a certain period of time, the pump shaft moves in series and the shaft vibrates. At this time, if hard small particles enter the mechanical seal The end face of the seal will wear the end face. The effective working time of the seal depends to a large extent on the application. To prolong the service life of the seal, the following points should be paid attention to: 1. Establish a suitable working environment in the seal cavity, such as effectively controlling the temperature of mechanical seals; removing solid abrasive particles; controlling the rapid fluctuations in pressure and temperature; forming between the seal faces Effective liquid film (double seal and sealing liquid if necessary). 2. The technical specifications of sealing can meet the requirements. 3. The rigidity and manufacturing precision of the pump are high. Considering the service life of the seal, not only the one-time investment of the pump (and seal), but also the economic loss caused by the failure of the seal, including: product loss; investment in backup equipment; and damage to equipment; man-hours and spare parts required to replace the seal, etc. The life limit of seals can vary widely, from just a few days in chemically aggressive conditions to 20 years of effective operation in olefin applications. 2. Reliability of mechanical seals In addition to the above-mentioned different working conditions, the service life of the seal will be greatly different, and the service life of the same seal will also be significantly different under the same conditions of use. This is similar to the test done with rolling bearings. Therefore, statistical concepts are applied when discussing seal reliability. We use the following two values to count the reliability of the seal: 1. L10 life The operating time when the number of failures in a sampled array of parts reaches 10% is called the L10 life. 2. Mean working life (MTBF) The mean working time is defined as the arithmetic mean of the interval time of sampling failures in sequence, MTBF=(L1+L2+??+Ln)/n where L1, L2——the working life of a single seal.
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