It should be self-evident that enclosures and items designed to be used outside or in harsh environmental conditions, should be designed to prevent water and dust ingress, but how do you know a product or enclosure really meets the ratings asserted by the manufacturer and what do all the IP numbers mean ?
Austest Laboratories is the leader in accredited IP testing with more than 150 products tested each year for various levels of ingress protection, from rain droplets to continuous immersion up to a depth of 6 metres.
It’s surprising how often we’re asked to “test a product to the highest IP rating it can go”. This could be taken as an admission by the importer or manufacturer that the product hasn’t been designed to meet a specific IP rating. We often find that even basic pre-compliance with a water hose or jet hasn’t been performed, prior to submission for formal testing.
The IP code is most often arranged into two characters, the first character being the protection against ingress of solid foreign objects and the second character being the protection against ingress of water with a combination of different first and second characters possible.
Whether you intend your product to be installed in a dry environment or fully exposed to the elements, to fully ensure that the enclosure of your product performs to the IP rating that is required for safe and reliable operation, testing to AS 60529 is a must.
IP First Numeral – Protection from solid objects/dust, IP
|IP1X||Protection against solid objects > 50 mm|
|IP2X||Protection against solid objects > 12 mm|
|IP3X||Protection against solid objects > 2.5 mm|
|IP4X||Protection against solid objects > 1 mm|
|IP5X||Protection against dust (limited ingress allowed, no harmful deposit).|
|IP6X||Fully protected from dust (dust tight).|
IP Second numeral – Protection from moisture/liquids
|IPX1||Protection from vertically dripping water|
|IPX2||Protection from sprays/dripping of water up to 15ofrom vertical.|
|IPX3||Protection from spraying water up to 60o from vertical.|
|IPX4||Protection from spraying water (all directions) – limited ingress OK provided no hazard.|
|IPX5||Protection from low pressure jets of water (all directions) – limited ingress OK provided no hazard.|
|IPX6||Protection against powerful jets of water, limited ingress OK provided no hazard|
|IPX7||Protection from temporary immersion|
|IPX8||Protection from continuous immersion|
Design tips based on our experience with IP testing
- When selecting seals, make sure they are designed to meet the number of times the door, gland or aperture will be opened/closed over the anticipated life of the product.
- An even and adequate compression force is critical for a seal to perform correctly. Careful consideration should be made in to how and where the compression force is applied and the amount of compression on the seal. E.g. adding extra locks to an electrical cabinet door can help distribute the compressive force on the door seal.
- Grooves for seals to seat in (o-ring seats) can provide a method to help ensure the seal is positioned correctly during installation. O-ring seats can also help improved sealing by distributing the compression force and provide increase resistance to differential pressure conditions.
- An o-ring should be compressed up to a maximum of 30% in most applications.
- Hard 90o bends in seals are usually a primary point of failure. Ensure seals are given a fairly wide radius when rounding corners.
- Cable entries, glands or otherwise need to suit the cable shape and size. Often, a Device Under Test (DUT) has more than 1 cable entry point with cables being positioned at angles other than 90 degrees. That creates difficulties at sealing of the entry.
- Small enclosures made from plastics often have the mating interface too weak (flimsy) with the ridge pressing on the seal being thin and sharp but not straight so it misses the seal at some parts along creating gaps in the seam.
- Spot welded sheet metal enclosures need to be silicone if that fits the design aspirations in the context of IP Codes of protection. Silicone is easy to apply.
- Seals around the doors are regularly split. If the flange is not continuous there can be gaps that permit water jets passing to the gap in the seal and entering the enclosure. Therefore, positioning of the seal joints is to be given consideration.
- Door locks are often a point of failure. The outer thread on the lock barrel is not dust and water tight, for example. The locking system should be prototyped and tested in-house until the desired outcome is achieved. Again, application of silicone sealant may save the situation.
- Drain holes should be considered as part of a solution.
- Birthing vents and filter inserts should be designed to prevent water jets overcoming the barrier if directed under particular angles.
- Be careful to ensure the products mounting instructions do not compromise the protection levels of the product by providing poorly designed fixing methods.
For designers of equipment that requires an IP rated enclosure, it may also be surprising to find that there is no database or listing of accredited IP products or results, with product IP ratings largely a self-declaration process. It’s therefore important to ask for evidence of compliance in the form of an accredited test report from an independent lab, if purchasing an enclosure that may be used to house electrical or other components.
Product liability issues will directly impact the manufacturer of the end product, so don’t simply rely on the IP rating labelled on the product or sales brochure, ask for evidence of compliance.
Austest Labs provides comprehensive accredited IP testing in our Sydney and Melbourne labs, Contact us here for a quote.