Industrial sites such as oil refineries, chemical plants, grain processing facilities, and certain manufacturing or nuclear facilities often contain hazardous (explosive) atmospheres.
In these environments, a spark or excessive heat from electronic equipment can ignite flammable gases, vapors, or dust. Traditionally, engineers used explosion-proof enclosures, purging, or intrinsically safe design to protect electronics in these areas.
Today, fiber-optic connectivity has emerged as a powerful solution to safely integrate computers and human-machine interfaces (HMIs) into hazardous locations.
Fiber-optic cables carry data as pulses of light instead of electrical currents. This fundamental difference offers several key benefits in explosive atmospheres:
Unlike copper wiring, fiber optics do not conduct electricity. This means they won’t produce sparks or arcs that could ignite a flammable atmosphere.
The absence of electrical currents also eliminates the risk of short-circuits or static discharge from data lines. In a Class I Division 1 or Zone 1 area (where flammable gas is present during normal operation), reducing ignition sources is critical. Fiber cables inherently reduce one major ignition risk associated with signal wiring.
Industrial sites are filled with electromagnetic interference (EMI) from heavy machinery, motors, and radio equipment. Fiber optics are immune to EMI, ensuring reliable data transmission even in electrically noisy environments.
For example, in a petrochemical refinery or a manufacturing plant with large motors, fiber links will not suffer the signal degradation that copper cables might. Additionally, fiber dielectric nature provides immunity to lightning and power surges. This is a big advantage for outdoor facilities like pipelines, where long communication lines are vulnerable to lightning strikes.
Fiber optics can transmit data over much longer distances than standard Ethernet copper cabling. In sprawling industrial complexes, critical control systems might be hundreds of meters away from central control rooms. Fiber links effortlessly cover these distances without loss of signal quality. This allows operators to keep computers and servers in safe control buildings while using fiber to connect to terminal units (monitors, thin clients, or PLCs) in hazardous field locations.
Because fiber cables are non-conductive, they isolate connected equipment from ground potential differences. Variations in ground potential between pieces of equipment can cause current loops on copper wiring, creating spark hazards and electrical noise. Fiber connectivity avoids this issue entirely, simplifying compliance with hazardous area electrical standards and improving overall system stability.
While fiber optics eliminate electrical ignition sources, fiber cables still require proper safety measures in explosive atmospheres.
The light transmitted through fiber, especially from high-power lasers, can become an ignition source if misused or if a cable is damaged. For instance, a broken fiber cable emitting concentrated light could heat up dust or gas in a confined space. International standards guide the safe use of optical fiber in such scenarios.
One important standard is IEC 60079-28, which addresses optical radiation in explosive atmospheres. It outlines methods like limiting the optical power (“op is” low-energy output) and automatically shutting down the light if a fiber is damaged. In essence, fiber hardware designed for hazardous areas must ensure that any light energy stays below ignition levels or remains fully contained even under fault conditions.
Practical safety measures include using certified fiber-optic interfaces, housing connectors in explosion-proof enclosures, and routing fibers in conduit or armored cable to protect them and contain any escape light.
Many industrial fiber devices also integrate circuits that cut off the laser if fiber is severed. Following these measures allows companies to reap fiber’s benefits while complying with hazardous area regulations (ATEX, IECEx, NEC, etc.).
Any industrial computer or monitor installed in a hazardous area must be properly certified for that environment (e.g. CID1 1 and/or Zone 1). Fiber can simplify compliance by allowing most electronics to stay in a safe area, with only a passive display or intrinsically safe interface unit in the hazardous zone. Even when a full PC or HMI must be on site, fiber links minimize how much wiring enters the area and help isolate the device from external electrical sources.
A few approaches leverage fiber optics to connect industrial computers and displays in hazardous environments:
One effective method is deploying remote thin client terminals or HMIs in the hazardous zone, connected by fiber to a host computer in a safe area.
The field terminal (an explosion-protected display with input devices) communicates over a fiber Ethernet link to a more powerful server located outside the danger area.
A Zone 1 HMI panel on an offshore platform can use fiber to relay data and remote desktop signals back to a control-room PC. This keeps high-heat, high-power computing hardware out of the explosive atmosphere while still providing on-site monitoring and control.
KVM extenders are another practical solution. Fiber-optic KVM extender pairs send a computer’s video output and keyboard/mouse signals over long distances (often several hundred meters) with no loss or lag.
This allows a computer in a non-hazardous room to be operated from a workstation in a hazardous area via fiber. A typical case is an automotive paint spray booth: the PC stays outside the booth, and a fiber KVM link connects to a monitor and controls inside.
The operator can work at the booth with no risk of igniting fumes, since only optical data is present at the station. Fiber KVM links also maintain excellent video quality without interference, even for high-resolution displays, ensuring the operator has a clear, real-time view of the system.
Fiber-optic connectivity in hazardous areas is already being applied across industries:
To maximize safety and performance when using fiber optics in explosive environments, experts follow a few best practices:
Choose fiber-optic devices and HMI hardware that are certified for the site’s hazardous classification. Such equipment features energy-limited circuits and sealed, rugged enclosures.
Run fiber cables through conduit or sealed trays in classified areas and use appropriate glands at entry points. This prevents flammable gas or dust from traveling along cable paths. Use fiber cables with durable jacketing or armor for protection.
Keep optical transmitter power within safe limits. Use inherently safe (low-power) optical devices or install interlocks that shut down laser output if a fiber is broken. Also train personnel not to disconnect live fiber connectors in hazardous zones unless they are using specially designed safe systems.
Place standard computers, servers, and other electronics in non-hazardous areas whenever possible. Only put the necessary explosion-proof or intrinsically safe interface devices in the hazardous zone and connect them via fiber. This minimizes energy within the dangerous area and simplifies compliance.
Regularly inspect fiber cables, connectors, and enclosures in hazardous areas. Ensure seals and glands remain intact and check that cables show no damage. Promptly replace any compromised components to maintain safety and reliability.
Fiber-optic technology has become a game-changer for deploying computers and displays in hazardous industrial environments.
By providing non-electrical, high-speed connections, fiber allows critical interfaces to operate in explosive areas without introducing ignition risk.
With careful design and strict adherence to safety standards, industries can achieve both safety and productivity in these environments, effectively bringing modern automation and connectivity into hazardous zones.
At VarTech Systems, our Project Managers—with an average of 15+ years of industry experience—are ready to customize a computer, monitor, or HMI workstation solution to meet your needs. Drawing from extensive backgrounds in manufacturing, military, oil and gas, and marine applications, they provide expert guidance throughout your project journey.
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Based in Clemmons, North Carolina, VarTech Systems Inc. engineers and builds custom industrial and rugged computers, monitors, and HMIs.
