MTTF/ MTBF and service life of an industrial pressure sensor: How long can I expect an industrial pressure sensor to last before it fails? Industrial pressure sensors are electronic instruments containing a number of components that are typically assembled in semi- or fully automatic manufacturing systems. Modern electronic pressure sensors do not contain any mechanical parts that are subject to wear and tear, and therefore need no regular maintenance or service. They are also expected to have a very long life if designed and manufactured using good engineering practice. Let’s have a look at the term “failure” over the life of a component: In order for system designers and engineers to project the expected failure rate of equipment, they differentiate between various failure modes: infant mortality, random failure, and wear out. All three failure modes contribute to the following graph of component failure rate, which reflects the well-known “bathtub”-curve (due to its distinctive shape). Figure 1: The failure rate of a device can be projected using statistical methods: MMTF/MTBF values represent the failure rate during the “Useful Life” and do not represent the useful life of a device.

## Mean Time to Failure (MTTF) and Mean Time Between Failures (MTBE)

Engineers typically use the terms “mean time to failure” (MTTF) and “mean time between failures” (MTBF) in discussions of device failure rates and lifetimes. However, it is important to understand that MTBF or MTTF values only represent the expected random failure rate during the useful life of a device and do not cover infant mortality or wear out. MTTF values are a method to express the random failure rate during the useful life of a device and are not equivalent to the useful life. It is therefore also important to understand that MTTF or MTBF does not make any representation of the length of the expected lifespan or service life of a device. Example: If a device has a MTTF of 100 years, it is expected to randomly fail within 100 years of continuous operation. That means if you have 100 devices in operation working simultaneously under the same conditions, you can expect that one of them will fail in any given year of operation. If you have 1000 devices in operation, statistically 10 devices will fail every year, or one device is expected to fail every 36.5 days. Keep in mind, however, that an MTTF of 100 years does NOT mean that the useful life of an individual device is 100 years! Figure 2: MMTF values explain the expected random failures of components during the useful life – not the life itself.   Check out WIKA Instrument’s Learning Center to learn more about the factors that impact the lifespan of an industrial pressure sensor, as well as how to pick the right pressure sensor for your specific applications. Guest Blogger: Eugen Gassmann Eugen Gassmann has more than 20 years of experience in the sales and marketing of industrial sensors, instrumentation solutions and automation systems. Gassmann, who wrote the book “Electronic Pressure Measurement,” regularly speaks at industry conferences about product management for industrial products in the B2B world. He has a degree in electronics from the University of Applied Science in Karlsruhe, Germany. He has worked for other global organizations, including Philips Electronics and Sartorius.