Design engineers often inquire about the Mean Time Between Failures (MTBF) of a fan to gauge the overall system reliability, but they should also pay attention to the L10 service life.
When choosing a DC fan for your system, it is essential to understand the critical ratings. Although MTBF usually gains most attention, at EAO, we advocate that the L10 Service Life offers a more precise measure of reliability.
The L10 life rating indicates the predicted lifespan of a fan. It represents the number of operational hours at which 90% of a sample batch of identical fans are expected to remain functional. Essentially, this means that only 10% of the fans are anticipated to fail before reaching the L10 lifespan. This measure provides a more precise estimate of a fan's durability compared to Mean Time Between Failures (MTBF).
Comparing MTBF and L10 Service Life
MTBF estimates the lifespan of a fan’s electronic components, expressed in millions of hours. In contrast, L10 Service Life, measured in thousands of hours, is based on the durability of the bearings and lubrication grease.
Importance of L10
The L10 life predicts the operational lifespan of a fan, indicating the number of hours at which 90% of identical fans remain functional, with only 10% failing before reaching this point. This metric provides a more accurate life expectancy than MTBF.
We determine the L10 life through accelerated life testing at high temperatures. For instance, the new 9RA series has an L10 service life of 60,000 hours at full speed at 60°C, equivalent to approximately 6.8 years, based on the grease and bearings’ lifespan. Notably, accelerated life testing by Sanyo Denki showed a 0% failure rate for this series.
60,000 hours = 18,900 hours x 2^((85°C - 60°C) / 15°C)
Given that L10 life is generally shorter than MTBF, we recommend using L10 life as the primary indicator for expected lifespan, as it is more accurate in real-world applications. Moreover, while many manufacturers provide lifespan estimates at 40°C, Sanyo Denki offers comparisons at both 40°C and 60°C—see the 9RA data excerpt below.
Emphasise Reliability
To ensure the longevity and performance of your system, prioritising L10 Service Life over MTBF offers a more precise evaluation. Sanyo Denki fans from EAO Ltd utilise dual ball-bearing designs for enhanced reliability and reduced noise throughout the fan’s lifespan.
For further assistance in selecting the right fan for your requirements, contact EAO sales representative Jason.slaughter@eao.com for expert advice and to determine if an onsite airflow test could help specify the optimal fans for your application.
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