Sealevel at 40: From PC Pioneer to Global Rugged Tech Powerhouse

LIBERTY, SC – January 16, 2026 – Sealevel Systems, Inc., a cornerstone of American industrial technology, is commemorating four decades of innovation with its year-long "Forty & Forward" campaign. What began in 1986 as a venture between husband and wife Tom and Susan O’Hanlan has evolved into a global leader in rugged computing, a testament to enduring vision and adaptability in a relentlessly changing technological landscape.

The company's 40th anniversary is not just a look back at a storied past but a definitive statement on its future trajectory. With plans for a major facility expansion and a growing workforce, Sealevel is reinforcing its commitment to designing and manufacturing critical technology solutions in the United States for the world's most demanding industries.

A Revolution in a Box

The seeds of Sealevel were planted two years before its official founding, in a moment of pivotal innovation. In 1984, Tom O’Hanlan, an inventor with a forward-thinking vision for connectivity, designed the first-of-its-kind RS-422/485 communication adapter for the nascent IBM PC. At the time, personal computers were largely confined to office desks and spreadsheet tasks. O'Hanlan's invention was a crucial bridge, a "giant step in how computers communicated" that connected the PC to the industrial world of automation, monitoring, and control.

This single component unlocked the potential for PCs to become the brains behind complex machinery and data collection systems in harsh environments. Recognizing the vast potential, Tom and Susan O’Hanlan founded Sealevel Systems in 1986, building a business on this cornerstone of connectivity. The company’s innovative spirit didn't stop there. In 1994, Sealevel further simplified industrial communication by developing an auto-enabled RS-485 circuit, a design that reduced communication errors and eliminated the need for complex software controls, showcasing a continuous drive to refine and perfect its technology.

"Our goal hasn’t changed," said Tom O’Hanlan. "From the factory floor to remote field deployments, we’re still focused on advancing computer connectivity so data can move faster, more reliably, and with consistent performance in real time."

Engineered for Extremes, Guaranteed for Life

From its origins in communication adapters, Sealevel has expanded its portfolio to over 350 core products, specializing in rugged edge computing and industrial I/O solutions built to withstand the planet's most unforgiving conditions. The company's hardware is a critical component in sectors where failure is not an option, including aerospace, military and defense, energy, and medical applications.

This reputation for durability is not merely a marketing claim; it is proven in the field. For example, a client in the high-vibration environment of the fracking industry, who had previously accepted a 20% failure rate from another vendor, found Sealevel's I/O device not only met but surpassed rigorous testing without a single failure. In another case, Sealevel provided a specialized embedded USB hub with locking connectors for a company developing AI-powered autonomous drones for utility grid monitoring. The solution solved a critical problem where drone vibrations were causing standard USB connections to fail, ensuring the reliability of the drone's vision system.

Backing this performance, Sealevel was the first in its industry to offer a lifetime warranty on all its manufactured I/O products, a bold statement of confidence in its American-made quality. This commitment is further solidified by its adherence to stringent international standards, holding both ISO 9001:2015 and the demanding AS9100D certifications, which are essential for serving the aerospace and defense sectors. These credentials ensure consistent, high-quality performance for mission-critical deployments, helping customers manage long lifecycles and reduce operational risk.

American Manufacturing Fuels Global Growth

Sealevel’s "Forty & Forward" campaign is aptly named, as the company is accelerating into its next decade with significant investments in its South Carolina operations. After outgrowing several previous locations in its early years, the company established its current 52,000-square-foot headquarters in Liberty in 2006. Now, plans are in place to break ground on a second facility on its 17-acre site this year, a move that signals robust confidence in future demand.

This physical expansion is a direct response to a burgeoning market. The global rugged computer market is projected to grow to over $7 billion by 2034, fueled by the rapid integration of IoT, AI, and 5G in industrial and defense settings. Sealevel is strategically positioned to capture this growth, with recent advancements in AI-ready products and high-speed connectivity solutions.

The company's growth is also reflected in its workforce. Its employee headcount surpassed 100 people in 2025, a notable increase from 66 just over a decade ago. This expansion represents a significant investment in engineering, manufacturing, and customer support talent, reinforcing Sealevel's role as a key technology employer in the region. This commitment to domestic manufacturing has earned the company state-level accolades, including the 'Best Innovative Company of the Year' in 2022 and the 'SC Transformation and Operational Excellence Award.'

A Legacy of Community and Commitment

Beyond its technological and economic contributions, Sealevel has cultivated a deep-rooted legacy of community engagement and corporate responsibility. This ethos, driven by the O'Hanlans, views the company's success as intertwined with the well-being of its employees and the surrounding community.

"When we look back on how we started and how we’ve grown, it’s inspiring to think about the creativity, energy, and effort that everyone here puts into moving Sealevel and our partners forward,” said Sealevel President Susan O’Hanlan. “We’re proud of what Sealevel has accomplished for our customers around the world, the opportunities it has created for our dedicated employees, and the impact we’ve made across the community that supports us.”

This commitment is demonstrated through tangible actions. The company has set an ambitious goal of increasing its charitable contributions by 38% year-over-year. In 2025, Sealevel sponsored the traveling Vietnam Veterans Memorial exhibit and supported numerous public-service organizations, while actively encouraging its employees to volunteer in local causes. This civic-minded culture extends from the top down, with Tom O'Hanlan having served as a Liberty city councilman and holding positions on several university and research foundation boards, including Clemson and Furman.

As Sealevel Systems celebrates its 40-year milestone, it stands as a powerful example of how sustained innovation, a commitment to quality, and a deep sense of place can build an enduring industrial powerhouse. By honoring its past and investing heavily in its future, the company is poised to continue solving the world’s most complex connectivity challenges for decades to come.