Sealing plays a critical role in protecting electrical connectors from the conditions that threaten long-term performance, but hermetic and environmental sealing are designed for very different applications. Tristan Stubbs, mechanical team leader at Bulgin, explains how engineers can choose the right level of connector protection.
Tristan Stubbs, mechanical team leader at Bulgin
Sealing is one of the most important considerations when specifying electrical connectors for demanding applications, protecting the interface where power or data is transferred and helping to maintain long-term performance. However, a connector in an outdoor installation exposed to rain and dust faces very different risks compared to one used in a vacuum chamber or a pressure-sensitive system.
This is where the choice between hermetic and environmental sealing becomes important. Both approaches protect electrical systems, but they do so in fundamentally different ways. Hermetic sealing provides complete atmospheric isolation, preventing gases or moisture from passing between two environments. Environmental sealing, in contrast, protects against external contaminants such as water, dust and dirt. Choosing between the two depends on understanding the true risk to the application, rather than simply selecting the highest possible level of protection.
Protection starts with the application
The starting point for any connector specification should be the operating environment. In many industrial and outdoor systems, the main threat is ingress of moisture, dust and particulate matter, which could compromise performance or safety. Poorly protected connector interfaces can be subject to corrosion, short circuits or signal degradation over time.
Applications such as transport infrastructure, renewable energy systems, outdoor lighting and industrial equipment therefore require connectors that can maintain reliable performance despite long-term exposure to challenging conditions. In these situations, environmental sealing can prevent contaminants from reaching the electrical contacts, while allowing the connector to remain practical, serviceable and cost effective for industrial use. The level of protection is commonly defined through Ingress Protection, or IP, ratings, giving a recognised framework for matching connector performance to expected exposure.
Other applications, such as vacuum systems, require a more specialised approach. Pressure-sensitive equipment, aerospace assemblies, and certain medical and semiconductor environments may need to maintain a controlled internal atmosphere, preventing even microscopic gas transfer between two spaces. In these cases, hermetic sealing becomes a functional requirement to maintain system performance, as even minimal gas ingress could compromise performance or safety. Using an environmentally sealed connector in these conditions would leave the application under-protected.
Understanding hermetic sealing
Hermetically sealed connectors are engineered to allow electrical power or signals to pass through a boundary without allowing gases or moisture to leak through the connector body.
This is typically achieved using glass-to-metal or ceramic-to-metal bonding techniques, creating a rigid and permanent barrier between insulating materials and metallic components. The result is a gas-tight seal that maintains atmospheric isolation under vacuum or pressurised conditions. This type of construction is used in highly specialised applications where even very small amounts of gas ingress could affect system performance, safety or process stability.
Because these connectors are designed for such demanding conditions, their performance must be verified through appropriate testing. Helium leak testing is commonly used to measure extremely low leak rates and confirm that the connector maintains gas-tight integrity.
Precision to this degree, of course, adds complexity. Hermetically sealed connectors typically require specialist materials, tightly controlled manufacturing processes and higher development costs than environmentally sealed alternatives. This complexity is justified in applications where atmospheric containment is essential. However, for many industrial and outdoor systems, hermetic sealing would add cost and design burden without delivering a practical benefit. Choosing the correct sealing method helps engineers to protect performance but still balancing reliability, affordability and serviceability.
Environmental sealing in real-world conditions
Environmentally sealed connectors are designed for applications where the primary challenge is exposure to liquid and particulate ingress. Rather than creating an airtight barrier, they use engineered housings, elastomeric seals, O-rings and gaskets to block water, dust and dirt from reaching the electrical contacts. These sealing systems are particularly important in connectors used outdoors or in industrial settings, where equipment may be exposed
to rain, washdown, high humidity or airborne particulates. When correctly assembled, the sealing elements create a compression barrier at the connector interface, helping to maintain electrical performance over long periods of use.
Environmental sealing is usually specified through IP ratings. IP66 indicates protection against powerful water jets, IP67 and IP68 relate to immersion under defined conditions, and IP69K indicates protection against high pressure, high temperature washdown.1,3 These ratings allow engineers to select a connector according to the conditions it is expected to face, rather than relying on broad assumptions about what constitutes a ‘harsh’ environment.
Building reliability into connector design
Reliable connector design depends on matching the sealing method to the demands of the application. In many cases, environmental sealing offers the most practical balance of protection, durability and cost. It safeguards electrical contacts from moisture and dust ingress, ensures long-term operation and avoids the additional complexity of hermetic sealing where it is not needed. However, in high-precision pressurised environments, nothing short of hermetic sealing will do. Understanding the difference between hermetic and environmental sealing allows engineers to make more precise specification decisions. Choosing protection that reflects the true operating conditions will ultimately reduce risk, control cost and ensure that each connection performs reliably throughout its intended service life.
Learn more: www.bulgin.com
For more Connectors products/news: Cables & connectors Archives – Design Solutions
