Identifying the Correct Electrical Enclosure Gasketing
First, let’s identify if or why you need to use electrical enclosure gasketing. The function of a gasket is to not only protect electronic components contained in electrical housings from outside elements such as weather, but also to prevent electrical hazards from escaping the unit. The proper gasket will provide a tight seal in both indoor and outdoor enclosure applications, with the ability to withstand the life of the product.
Poor seals and low-quality gaskets can cause damage and serious safety issues. An inefficient design can allow gases and liquids to leak into your devices, it can cause system failures that require time-consuming repairs or even fires that put your facility and employees at risk.
Ensuring proper performance for your enclosure gasketing
Before you make material selections and/or installation options, it’s important to understand your specific application requirements. Most applications need to comply with various ratings such as NEMA, UL and IP or military standards.
Ask the following questions:
- Temperature – what temperature range will be required?
- Location – will the application be indoor or outdoor?
- Flame resistance – will the material require a certain flame rating?
- Outgassing – will material outgassing harm the internal components?
- Gap spacing – what is the area needed to be filled by the gasket?
- Gasket function – what protection will the gasket need to provide? (air, liquid, vibration, EMI shielding)
Additional engineering design considerations:
- Protect the gasket – a flange on the door that protects the gasket from a direct pressure blast will diffuse the force and greatly improve the chances of passing a wash down test
- Door latching – helps provide a proper means of compressing the gasket
- Material selection – ensure the appropriate gasket material is used for your environmental requirements
- Gasket rebound – rebound or resistance to taking a compression set can be critical, especially on door gaskets that are being unseated regularly
- Functional life – longevity of the gasket will depend on how the material is used: exposure to UV, ozone, temperature, chemicals, and mechanical wear
- Venting – pooled water can get sucked into an enclosure during a rain shower from the vacuum affect from cool rain on a hot box
Material selection for your enclosure gaskets
There are a variety of materials to choose from when it comes to providing the perfect seal on an enclosure. Look for an option that is both cost-effective and delivers optimum performance.
Common materials used:
- closed cell sponge rubber (neoprene, PVC)
- cellular urethane
- polyethylene
- silicone
Which application process should you utilize?
There are three common types of gaskets:
- Foam-in-place – they require a special liquid polyurethane spray to be applied to the edges of the mating, that once dried and hardened can provide a good deal. A downside to this option is that it can easily be damaged and can be a costly application process
- Strips – these are typically used as a temporary solution until a better gasket option can be found. It often leaves gaps and leaks.
- Custom water jet cut – they can be cut from a variety of materials to the precise size and thickness you need
NEMA / UL 50 Enclosure Gaskets
Technically there aren’t any NEMA gaskets since the enclosure is evaluated as a whole, but there are gaskets and gasket materials that will help an enclosure pass a specified test.
NEMA / UL 50 Type | Description | Common Material Types |
Type 1 | Basic, indoor enclosures, protects from dust and falling dirt | Open cell or closed cell foams, closed cell sponges |
Type 2 | Indoor enclosure, protects against dust and falling dirt as well as dripping / light splashing of water | Fine pitched open cell (microsellular) foams or closed cell foams, closed cell sponges |
Type 3 | Indoor / outdoor enclosure, protects against windblown dust and falling dirt. Also protects against water (rain, sleet, snow and effects of ice formation) | Closed cell foams or closed cell sponges |
Type 4 | Indoor / outdoor enclosure, protects against windblown dust and falling dirt. Also protects against water (rain, sleet, snow, splashing water and hose directed water and effects of ice formation) | Closed cell foams or closed cell sponges |
Type 5 | Indoor / outdoor enclosure, protects against falling dirt, settling airborne dust, lint, fibers and flying debris. Also protects against water (rain, sleet, snow, splashing water and hose directed water and effects of ice formation) | Closed cell foams or closed cell sponges |
Type 6 | Indoor / outdoor enclosure, protects against falling dirt. Also protects against water (hose directed water and the entry of water during prolonged submersion at a limited depth and effects of ice formation) | Closed cell foams, closed cell sponges, low and mid durometer solid elastomers |
Type 12 | Indoor enclosure (w/o knockouts, 12K w/ knockouts), protects against falling dirt, settling airborne dust, lint, fibers and flyings. Also protects against water (dripping and light splashing) | Fine pitched open cell (microcelluar) foams or closed cell foams, closed cell sponges |
Type 13 | Indoor enclosure, protects against falling dirt, settling airborne dust, lint, fibers and flying debris. Also protects against water (dripping and light splashing). Some protection against spraying / splashing / seepage of oil and coolants | Chemical compatible closed cell sponge |
IP Enclosure Gaskets
The intentions of the IP code are similar to NEMA and UL. The first digit (IP 6X) refers to solid particle. The second digit (IP X1) refers to water. For example, IP%$ refers to an electronic enclosure capable of sealing out dust, water and protect against vertically dripping water.
IP Spec | 1st Digit | 2nd Digit | Common Material Types |
IP53 | 5 Protect from dust and water, some dust ingress allowed but not to interfere with function | 3 Protect from spraying water (angle up to 60 from vertical) | Closed cell foams, closed cell sponges, microcellular foams |
IP63 | 6 Completely protected from dust and water ingress | 3 Protect from spraying water (angle up to 60 from vertical) | Closed cell foams, closed cell sponges, microcellular foams |
IP64 | 6 Completely protected from dust and water ingress | 4 Protect from splashing water (from any direction) | Closed cell foams, closed cell sponges, solid rubber |
IP65 | 6 Completely protected from dust and water ingress | 5 Protect from pressure jets of water (from any direction) | Closed cell foams, closed cell sponges, solid rubber |
IP66 | 6 Completely protected from dust and water ingress | 6 Protect from strong pressure jets of water (from any direction) | Closed cell foams, closed cell sponges, solid rubber |
IP67 | 6 Completely protected from dust and water ingress | 7 Protect while temporarily submerged (up to 1 meter) | Solid rubber |
EMI Enclosure Gaskets
Commercial applications, not held to military specifications, typically yse nicel graphite filled silicone. The Nickel particles are mixed into silicone polymers and cured into conductive rubber sheets or rolls. Larger EMI gaskets can be made with strips or interlocking strips to maximize the yield.
For gaskets required to meet MIL-DTL-83528, the polymer and conductive fill are defined by specification types:
- Type A – silver coated copper + silicone (65 durometer)
- Type B – silver coated aluminum + silicone (65 durometer)
- Type C – silver coated copper + flurosilicone (75 durometer)
- Type D – silver coated aluminum + fluorosilicone (70 durometer)
- Type M – silver coated glass + silicone (65 duromater)
Keep your electronics interference-free
At A&J we use a .140 diameter tubular gasket (210-1130) that is added to the extrusion grooves and consists of a silicone inner core that is plated with silver / aluminum for the seams between the frame members that are joined together.
Our enclosures are attenuated to 60 DB from 150 Hz to 1 million Hz and 40 DB from 1-2 million Hz in accordance with MIL-STD-461G for EMI/RFI shielding. Our team of professionals can help you determine the type of shielding your rack or enclosure needs and install it quickly and efficiently. Contact us today!
