1. Sealed enclosures
To reduce exposure to macro-environmental stressors.
Related Tags
Environmental exposure is one of the most significant yet underestimated threats to industrial networks. When the hardware that supports them is deployed in outdoor cabinets, tunnels, transport systems or chemical plants, it’s subjected to harsh conditions. Humidity, condensation, pollutants and temperature cycling can accelerate corrosion and result in failure, undermining long-term system reliability.
Making it even more challenging is the fact that there’s a disconnect between how industrial-grade hardware is specified and where it’s deployed. Even if equipment looks adequate on a datasheet, it may not be designed to operate in harsh conditions.
For example: While our standard enclosures offer robust protection for typical environments, additional protective measures at the PCB (printed circuit board) level, such as conformal coatings, offer extended long-term reliability and performance in harsh conditions.
When standards and reality don’t match
Most networking devices are designed and certified according to international safety standards that assume a defined “standard operating environment.”
For example, UL 61010-1:2012 defines a standard operating environment as follows:
- Ambient temperature: 5 degrees C to 40 degrees C
- Relative humidity: up to 80% at 31 degrees C, decreasing linearly to 50% at 40 degrees C
- Pollution degree: controlled indoor environments
But real-world deployments rarely align with these conditions. Devices are subjected to high humidity, condensation cycles, salt-laden air and/or industrial gases that can push them well beyond what they’re certified to withstand.
Environmental conditions that impact reliability
There are many ways the environment can affect electronics when networking devices are installed outside standard operating environments. Understanding these factors is critical to selecting the right protection strategy for your hardware so you can unlock new possibilities.
Pollution degrees
International standards like IEC 60950, UL 60950-1 and UL 62368-1 use different classifications to describe types and severity of environmental contamination that could impact the safety and reliability of electronic equipment.
Classification directly affects insulation distances and protective measures.
- Pollution Degree 1: An environment with no pollution or only dry, non-conductive pollution, commonly found in hermetically sealed environments.
- Pollution Degree 2: An environment with non-conductive pollution during normal operation, although conductivity may occur due to temporary condensation. This classification is common for clean indoor industrial environments.
- Pollution Degree 3: An environment with conductive pollution or dry contamination that becomes conductive through expected condensation. This is common in workshops, tunnels and outdoor enclosures.
- Pollution Degree 4: An environment that features persistent conductive pollution due to salt spray, corrosive mist or industrial gases. It’s often seen in offshore platforms and chemical plants.
Macro vs. micro environments
To apply the right protection strategy, it’s important to distinguish between environments.
- Macro environment: Describes overall ambient conditions around the device.
- Micro environment: Describes the internal conditions of the device inside the housing or directly on the PCB.
Even if the macro environment is harsh, it’s possible to maintain a Pollution Degree 2 micro environment with appropriate protective measures, such as sealed enclosures, condensation control and conformal coatings.
Devices operated in harsh macro environments without sufficient protection of the micro environment are far more likely to experience corrosion, loss of insulation resistance or premature failure.
Humidity and condensation risks
Condensation develops when warm, moisture-laden air contacts cooler surfaces and releases liquid water. This is common in basements, tunnels, outdoor cabinets or enclosures with limited ventilation, especially when internal surfaces cool rapidly during nighttime or power-down cycles.
Even small temperature drops of between 1 and 2 degrees C can initiate moisture formation on metal housings or mounting rails, distributing condensed water throughout the enclosure.
Once present, moisture can settle on PCBs and form thin conductive films that reduce insulation resistance. Airborne contaminants such as dust, sulfur dioxide, nitrogen oxides and chlorine further increase risk by dissolving into moisture and creating corrosive or conductive residues.
Condensation can occur even when the measured ambient humidity is well below 100%, as long as the equipment or its components are colder than the surrounding air’s dewpoint. Conditions like these frequently arise during equipment shutdowns, nighttime cooling or operation in humid environments.
Devices exposed to condensation and humidity without adequate protection are at high risk of gradual degradation and unexpected failure in the field.
Exposure to corrosive gases and pollution
Corrosive gases and airborne pollutants pose a major risk to electronic assemblies. Sulfur dioxide (SO₂), nitrogen oxides (NOₓ), hydrogen sulfide (H₂S) and chlorine (Cl₂) can react with moisture in the air or on surfaces to form acidic films that accelerate the corrosion of solder joints, connector pins and exposed metal traces on PCBs.
Dust and fine particles can accumulate on electronic surfaces and attract humidity over time. This can form conductive paths, reduce insulation distances and increase the risk of electrochemical migration and short circuits. In many cases, degradation isn’t detected until failure occurs.
Devices installed in polluted environments without adequate protection are particularly vulnerable to corrosive gases and pollution, leading to reduced service life and unexpected downtime.
Conformal coating as part of a dual-layer protection approach
One way to address these environmental risks is through conformal coatings. It’s part of a dual-layer protection concept that combines:
2. Conformal coatings
To provide a direct protective barrier at the PCB level.
By combining these two measures, you can maximize hardware reliability, extend service life and reduce unplanned downtime in demanding industrial applications.
What is a conformal coating?
A conformal coating shields PCBs from environmental stressors—moisture, dust, corrosion and chemicals—with a thin polymeric layer (between 25 µm and 75 µm).
The benefits of conformal coatings
Conformal coatings provide several benefits for industrial networking equipment deployed in challenging environments.
It’s particularly valuable in Pollution Degree 3 and Pollution Degree 4 environments where standard enclosure protection isn’t sufficient.
| Benefit | Description |
| Moisture protection | Prevents moisture and condensation from forming conductive paths on the PCB surface |
| Corrosion resistance | Shields components and traces from salt mist and corrosive gases like SO₂ and H₂S |
| Extended lifespan | Minimizes degradation caused by temperature cycling, pollutants and humidity |
| Better electrical insulation |
Increases dielectric strength, supporting higher creepage and clearance distances |
| Improved field reliability | Reduces failure rates, especially where full enclosure sealing is limited |
| Lower maintenance costs |
Decreases the need for servicing or replacement due to corrosion or moisture-related failures |
| Less unplanned downtime | Prevents unexpected failures and emergency service interventions |
Validated conformal coatings for harsh environments
As networks continue to move into harsher, more exposed locations, environmental protection is a requirement. Conformal coatings give you a way to close the gap between how equipment is specified and where it operates. By understanding pollution degrees and limitations of enclosure protection, you can take proactive steps to safeguard critical infrastructure.
Hirschmann, a Belden connected brand, offers conformal coatings as an option for most product families, providing enhanced protection for electronic assemblies exposed to harsh environmental conditions. Part of our complete connection solutions, this added layer of protection helps ensure that links remain reliable from the field device to the control room.
The coating has been extensively tested and complies with DIN EN 60068-2-60 Method 4, which simulates 31 days of exposure to corrosive gases like H₂S, SO₂, NO₂ and Cl₂. During testing, devices remained fully operational and exhibited no corrosion on the PCBs. These results prove the suitability of Belden’s conformal coatings for environments beyond standard Pollution Degree 2 conditions.
Our conformal coating process is UL Recognized (E80315) and conforms to industry standards like IPC-CC-830B for coating performance and IPC-A-610D for application quality.