Why You Need a Harsh Environment Computer for Industrial Applications

A harsh environment computer is a computer designed and tested to keep running where heat, cold, dust, water, corrosion, vibration, unstable power, electrical noise or explosive atmospheres would stop an ordinary PC. It is defined by the environment it survives rather than by its shape: a fanless box PC, a sealed panel PC or a vehicle computer can all be harsh environment computers.

Edge computing does not only happen in clean, temperature-controlled rooms. Sites range from fairly benign to extremely harsh, and the cost of a failed computer is usually the stopped line or the site visit, not the hardware. Rugged computers are built for these places, with wide temperature ranges, fanless sealed cooling, shock and vibration resistance and wide power inputs. This guide starts from the environment: it maps each harsh factor to the failure it causes, the design that prevents it and the standard it is tested to, then profiles common harsh sites so you can check whether your application needs one.

Each harsh factor causes a predictable failure. A harsh environment computer answers each one with a design measure and a test that proves it. The table is the master reference for this guide.

The detail behind the defence standards is in our guide to military standards for rugged computers, and our guide to what a rugged computer is covers the definitions and build types.

Edge computers are often built into a larger system, inside a cabinet or outdoors, and can see extreme cold and heat. The air inside a chassis or cabinet can run much hotter than the surrounding air because of heat from processors and GPUs, so it is important to use the higher figure when deciding which temperatures the computer must handle.

Ordinary industrial PCs are often rated around 0 to 50 °C or −10 to 60 °C, while a harsh environment PC may need −40 to 70 °C or more. Components come in grades too: commercial parts are typically rated 0 to 70 °C and industrial parts −40 to 85 °C. Our FAQ on the industrial temperature range explains the grades, and wide temperature computers are rated for the full span.

Ratings usually depend on processor power: many fanless systems are rated to 70 °C with a 35 W processor but lower with a 65 W part. When a processor runs out of thermal margin it slows down, which our guide to thermal throttling explains.

For many years fanless embedded PCs have used heatsinks of different designs to keep cool. To support more powerful processors, larger finned heatsinks increase the surface area and shed heat by natural convection. Because they are fanless and ventless, these computers keep out the dust and particles that would clog a fan and its filter, which lets them work in dusty and dirty places with little maintenance. Our guide to the benefits of fanless computers covers the advantages in more depth.

For outdoor and food processing applications, the ingress protection rating rises until the computer is waterproof. The IP rating shows how well a computer is protected against solids, by its first digit, and liquids, by its second. Our IP rating chart explains every code, and our FAQ on IP5X vs IP6X covers dust.

Food and drink sites add hygiene to sealing; our guide to hygienic design for washdown computers covers the extra requirements, and waterproof computers cover every rating from IP65 to IP69K.

Corrosive gases, such as hydrogen sulphide in wastewater plants and chlorine in chemical works, and salt in coastal and marine air, attack connectors and circuit board tracks long before they affect a sealed case. ISA-71.04 grades airborne corrosion from G1 (mild) through G2 and G3 to GX (severe), which gives a common language for specifying protection.

• Conformal coating on the circuit boards protects against moisture and corrosive gases; our FAQ on conformal coating explains the types.
• Sealed chassis keep corrosive air away from the electronics altogether, with gold-plated or sealed connectors outside.
• Stainless steel housings resist salt and cleaning chemicals; our guide to 304 vs 316 stainless steel explains which grade suits which site.
• Condensation control matters where computers cycle between cold and warm air, such as cold stores and outdoor cabinets.

Computers in vehicles must withstand constant vibration and occasional heavy shock, and this is where rugged computers excel: they are often tested to the standards the transport industry expects, which gives assurance that the computer will not be affected by the shock and vibration of everyday operation. Damping brackets add further isolation when mounting a rugged computer in a car, truck, aircraft, boat or train.

Inside, the design removes the parts that vibration loosens: memory is soldered down or locked, hard drives are replaced with solid state storage, internal cables are removed in favour of board-to-board connections, and external connectors lock with screws or M12 couplings. Computers in vehicles are typically tested to MIL-STD-810H or IEC 60068 vibration and shock, and railway computers to IEC 61373; our FAQ on MIL-STD-810H explains the methods.

Rugged computers are built to run from a wide range of power sources and can connect directly to a DC supply where no AC adapter is available. That needs a wide input range, typically 9 to 48 V DC, and protection against the dips, surges and reverse polarity that vehicle and plant supplies produce. Vehicle computers usually add ignition control, which powers the computer on and off with the engine after a set delay so data is not corrupted; our guide to configuring ignition control covers the settings.

Electrical noise from drives, motors, welders and radio transmitters causes resets and dropped links that look like software faults. A metal chassis, isolated serial and digital I/O, and immunity tested to IEC 61000-6-2 keep the computer stable; our FAQ on electromagnetic interference explains the sources.

Where flammable gas, vapour or dust may be present, the computer must not become an ignition source. Intrinsic safety protects against that by limiting the electrical and thermal energy in the circuit so a spark or hot surface cannot ignite the atmosphere; other methods include non-sparking design, barriers, earthing and shielding. ATEX is the European framework and IECEx the international scheme, and North America uses the Class and Division system.

Most computers in hazardous areas are Zone 2 or Division 2 non-incendive designs; Zone 0 and Zone 1 equipment is rarer and more specialised. Our FAQ on intrinsically safe vs non-incendive explains the difference, and intrinsically safe computers and intrinsically safe panel PCs cover the certified options. Always match the marking to your area classification.

Any industrial application that exposes a computer to extreme temperatures, humidity, dust, vibration or shock can benefit from a harsh environment computer. These are the sites we see most often, with the hazards that dominate each and the specification that usually follows.

Sector standards add to the general ones: our guides to EN 50155 for rolling stock and IEC 60945 for marine computers explain the two most common. For outdoor installations where the computer sits inside a cabinet, our guide to outdoor computer enclosures covers solar heat and condensation.

One self-check helps: if your computer failed tomorrow, would someone have to travel to replace it, and would anything stop while they did? If the answer is yes, the environment is harsh enough to justify a computer built for it.

One computer for each of four harsh settings, with facts from each product page. We configure, image and test every computer before it ships.

For more, see waterproof box PCs and rugged panel PCs. Our guide to industrial grade computers explains how the industrial and rugged grades differ.