The Evolution of Zetec's Metal Internal Impedance (MIZ) Instrument Series

The Beginning: 1968: As Nuclear Power Flourishes, Zetec Innovates

Zetec was founded at a small office and dairy barn just outside Seattle in Issaquah, Washington. With an analog, single-frequency eddy current tester and bobbin tubing probe that it designed and manufactured, the company wins a government contract to inspect steam generators at nuclear power plants. As nuclear power flourishes in the 1970s and 1980s, Zetec becomes one of the industry’s leading developers of eddy current (EC) technology, supporting customers around the world with innovations including the first multi-frequency analog ET instruments; the first digital ET instrument; Eddynet networked ET inspection software; and MRPC 3-coil+point probe head.

The Beginning: Introducing the MIZ-1

The MIZ-1 holds a special place in the world of eddy current testing. As one of Zetec’s earliest commercial models, the MIZ-1 was a complex, single-frequency device. Though specific information about its exact applications is scarce, it is widely regarded as the starting point in Zetec’s long history of innovation in the eddy current testing domain.

While the MIZ-1 was a basic model by today’s standards, it helped establish Zetec’s reputation in the field, setting the stage for the company’s development of more advanced instruments. The device became a stepping stone for further innovations that would transform eddy current testing into the versatile and efficient process it is today.

Pictured here: The vintage MIZ-1, a rare glimpse into the early days of Zetec’s eddy current testing legacy.

The MIZ-Series Evolution

Following the MIZ-1, Zetec introduced a series of increasingly sophisticated instruments, each building on the strengths of its predecessor. Here’s a brief overview of key models in the MIZ-series:

• MIZ-12: One of the early models that expanded on the single-frequency approach, allowing for more comprehensive eddy current testing with multi-frequency capabilities​

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• MIZ-17: This model took a significant leap forward by integrating with Tektronix 5000-series oscilloscopes, offering enhanced data visualization and compatibility with a wider range of testing setups​

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• MIZ-21B: One of the more portable models, designed specifically for field inspections such as surface crack detection and bolt hole inspections. Its portability made it a favorite for industries that required mobility​

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• MIZ-200: With support for both single and array probes, this advanced system is ideal for complex inspections, particularly in heat exchanger tube testing. Its multi-frequency capability allows for detailed defect detection across a range of materials​

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• MIZ-28: A modern marvel, the MIZ-28 is designed for high-speed heat exchanger tubing inspections, offering simultaneous and multiplexed injection technologies. This allows for efficient testing of a wide variety of tube materials, including carbon steel​

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Continuous Innovation

Zetec’s MIZ-series has always been defined by continuous innovation. From early single-frequency instruments like the MIZ-1 to today’s multi-frequency, high-data-processing systems, each model in the MIZ series has built on its predecessors to offer faster, more accurate inspections. Whether it's for power generation, oil & gas, or aerospace, Zetec’s instruments are now integral to ensuring safety and efficiency in critical infrastructure around the world.

Why Highlight the MIZ-1?

The MIZ-1 stands as a symbol of where it all began for Zetec. While newer models like the MIZ-28 and MIZ-21C boast cutting-edge technology, the MIZ-1 is a reminder of the early breakthroughs that made today’s innovations possible. For anyone who works in the field of eddy current testing, it's fascinating to see how far we’ve come—from analog single-frequency devices to highly sophisticated digital systems.

For a deeper look into Zetec’s current offerings and how their instruments are shaping the future of nondestructive testing, explore their full product line here.