solderic.com Hermetic relays provide airtight sealing that prevents moisture, dust, and contaminants from entering, ensuring superior reliability in harsh environments compared to sealed relays, which use less stringent methods to block external elements. Explore the detailed differences to understand which relay type best suits Your application needs.
Comparison Table
| Feature | Hermetic Relay | Sealed Relay |
|---|---|---|
| Enclosure Type | Hermetically sealed, airtight metal or glass enclosure | Sealed plastic or metal enclosure with an external gasket |
| Atmosphere | Filled with inert gas or vacuum for protection | Contains ambient air but protected from dust and moisture |
| Environmental Protection | Excellent protection against moisture, contaminants, and corrosion | Good protection, limited against extreme environments |
| Reliability | High reliability in harsh conditions | Moderate reliability, less suitable for extreme conditions |
| Application | Used in aerospace, military, medical devices, and harsh industrial environments | Used in general electronics, consumer devices, and industrial control |
| Lifespan | Long lifespan due to controlled internal environment | Shorter lifespan compared to hermetic relay under harsh conditions |
| Cost | Higher cost due to complex sealing process | Lower cost, simpler sealing methods |
| Size | Tends to be more compact for given power rating | Can be larger due to sealing design |
Introduction to Hermetic and Sealed Relays
Hermetic relays provide airtight and moisture-resistant sealing, ensuring long-term reliability in harsh environments such as aerospace and medical devices. Sealed relays, while protected against dust and splashes, typically use plastic or epoxy enclosures that offer less robust environmental shielding compared to hermetic versions. Choosing the right relay depends on Your application's exposure to extreme conditions and the requirement for longevity and stability in electrical switching.
Construction and Design Differences
Hermetic relays feature a fully sealed metal or ceramic enclosure designed to prevent moisture, dust, and gases from entering, ensuring high reliability in harsh environments. Sealed relays use plastic or epoxy coatings to protect the internal components but are less impervious to contamination compared to hermetic designs. The hermetic construction typically involves glass-to-metal or ceramic-to-metal seals, providing superior airtightness and long-term stability under extreme conditions.
Operational Principles
Hermetic relays operate by encapsulating the internal components in a vacuum or inert gas-filled enclosure to prevent contamination and ensure reliability, while sealed relays use a sealed casing to protect the contacts from moisture and dust without necessarily providing a vacuum environment. The operational principle of a hermetic relay relies on maintaining a controlled atmosphere for enhanced durability and stability in harsh conditions, whereas sealed relays depend on physical barriers to shield sensitive parts from external elements. You can choose hermetic relays for applications requiring high precision and longevity, while sealed relays suit environments needing moderate protection against contaminants.
Environmental Resistance and Protection
Hermetic relays offer superior environmental resistance due to their airtight, welded metal enclosures that prevent moisture, dust, and contaminants from entering, making them ideal for harsh and extreme conditions. In contrast, sealed relays use resilient plastic or epoxy seals that provide good protection against typical environmental factors but may degrade over time under severe exposure. Your choice depends on the required level of protection, with hermetic relays excelling in long-term reliability in corrosive or high-humidity environments.
Application Areas: Where Each Relay Excels
Hermetic relays excel in aerospace, medical, and military applications requiring airtight sealing to protect sensitive electronics from moisture, dust, and corrosive gases, ensuring long-term reliability in extreme environments. Sealed relays are ideal for industrial automation, HVAC systems, and automotive applications where protection against dirt, oil, and minor moisture is necessary, but extreme airtight conditions are not critical. The choice depends on environmental exposure and reliability demands, with hermetic relays suited for harsh, contamination-sensitive settings and sealed relays for general-purpose rugged use.
Reliability and Lifespan Comparison
Hermetic relays offer superior reliability and extended lifespan due to their airtight, corrosion-resistant metal or ceramic enclosures that protect internal components from environmental contaminants. Sealed relays, while also designed to prevent dust and moisture ingress, typically use plastic envelopes that may degrade faster under harsh conditions, potentially reducing their operational lifespan. Choosing a hermetic relay for your application ensures enhanced durability and consistent performance in demanding environments.
Performance Under Extreme Conditions
Hermetic relays offer superior performance under extreme conditions due to their airtight metal or ceramic enclosures, which protect internal components from moisture, dust, and corrosive gases, ensuring reliability in harsh environments. Sealed relays also provide protection by encapsulating internal parts, but typically in plastic or resin, which may degrade under high temperatures or aggressive chemicals. Your choice between the two should consider the operating environment's temperature range, humidity, and exposure to contaminants for optimal long-term performance.
Cost Analysis: Hermetic vs Sealed Relays
Hermetic relays generally incur higher manufacturing and maintenance costs due to their airtight, metal-ceramic construction ensuring superior environmental protection and reliability in extreme conditions. In contrast, sealed relays offer a more cost-effective solution with plastic or epoxy encapsulation, suitable for less demanding environments, reducing initial expenditure and replacement frequency. Evaluating total cost of ownership favors hermetic relays in mission-critical applications requiring longevity, whereas sealed relays optimize budget constraints for standard electronic use cases.
Maintenance and Serviceability
Hermetic relays offer superior maintenance and serviceability due to their airtight, corrosion-resistant enclosure that prevents contamination and extends operational life, reducing the frequency of servicing. Sealed relays, while protected from dust and moisture, may still require more frequent inspections and replacements as their seals can degrade over time, compromising reliability. The robust design of hermetic relays is especially advantageous in harsh environments where maintenance access is limited or costly.
Choosing the Right Relay for Your Needs
Hermetic relays offer superior protection against environmental factors like moisture and dust, making them ideal for applications requiring high reliability and long-term durability. Sealed relays provide adequate protection for general purposes but may not withstand extreme conditions as effectively. To choose the right relay for your needs, consider the operating environment, required lifespan, and sensitivity to contaminants.
Hermetic relay vs sealed relay Infographic
