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2010-06-30

What do you mean by Weatherproof?

Weather protection

What exactly do you mean by weatherproof?  Before specifying outdoor protection make sure that you define exactly what you require states Ian Gibson, technical director for Flexicon and chairman of both the IEC(worldwide) and CENELEC (European) committees that prepare conduit standards.

Search the internet and you will see terms such as suitable for outdoor use or weatherproof.  Be very careful, you need to substantiate such terms.  As a UK based manufacturer we certainly understand the vagaries of the weather! 

Bear in mind however, that we live in a temperate climate and conditions will vary greatly in different areas of the world.  If you are involved in international projects then the term weatherproof could be very different. 

 

Take flexible conduit as an example.  It protects power and data cables.  If you use it outdoors, then you must fully understand the local climate that you are specifying it for.  Manufacturers should have a wide range to choose from, Flexicon, for instance, has 45 different ranges with hundreds of variants.

So what needs to be considered for ‘weatherproof’?  Quite rightly most of us would refer to IP ratings, but this is not the only factor that needs considering.  You should also think about resistance to UV degradation, corrosion and its performance at different temperatures.

IP ratings

Starting with IP ratings, the first number refers to protection against solid objects or dust ingress and the second to protection against water ingress.

Table 1

It should be a given that dust should not enter the conduit system in harmful quantities.  Referring to table 1, the conduit should have a minimum IP5X rating and preferably be IP6X.

Water ingress could include rain, spray and possibly even shallow immersion.  It could also cover capillary action and suction induced by the rise and fall of temperatures, although conduit systems are normally vented to atmosphere at one end, which allows the air inside to expand and contract.

IP tests to IEC EN 60529 indicate a system’s performance, but they are very short tests on samples that have been assembled under ideal conditions. 

Referring to table 1, the duration of these tests are:

IPX4 – five minutes light spray

IPX5 – three minutes medium spray

IPX6 – three minutes high-pressure jet

IPX7 – 30 minutes immersed in 1 metre of water

IPX8 – at a pressure and time stated by the manufacturer (not often stated).

 

You need to be careful when referring to an IP rating for moisture ingress.  You should take a ‘belt and braces’ approach to prevent water ingress over a long period of time.

 

If you don’t know the orientation of the fittings, then you should specify IPX6 or IPX7.  If you are assembling the fittings on the underside of an enclosure then IPX5 or IPX6 may be suitable.

 

Resistance to Ultraviolet

Ultraviolet radiation from the sun will also affect the performance of plastic materials by breaking down the long polymer chains.  The result will be lower impact strength, less flexibility and lower fatigue life.  The amount of UV radiation will depend on location, climate and altitude.

At Flexicon, we would always recommend a black product to resist UV as the carbon black inside the material protects the polymer chains. 

Check what the manufacturer means by “UV resistant”.  At Flexicon we have generally added a certain amount of carbon black to ensure UV resistance for anywhere in the world. 

If you are in any doubt then ask for test reports showing a product’s UV resistance.

Manufacturers can make other colours UV resistant by adding a chemical UV resistant additive, but this is more expensive than adding carbon black.

Corrosion

If you are using metal conduit and/or fittings then corrosion could be an issue.

We would not recommend using galvanised steel outdoors, because it will rust.  Coated steel conduits are suitable as long as its IP rating is sufficient to prevent water getting into the conduit. 

Nickel-plated brass fittings will discolour through oxidisation over time and much more quickly in coastal areas.   If you need to use steel in marine environments then Grade 316 stainless is suitable.

Temperature

Finally consider the affects of temperature.  Generally the maximum temperature reached due to the weather is not an issue.  You should check the minimum temperature that the conduit may need to operate in however, to prevent damage by impact or bending during installation and use.

When you specify conduit you should always consider the potential hazards to which it might be exposed.

Similar to most reputable conduit manufacturers we have certain products that are suitable for outdoor use.  Take our LTP range, when it is used with stainless steel fittings, it has an IP rating of up to 69k and can be used for temperatures from -20oC to 105 oC. The LTPHC range extends this temperature range to between -45 oC to 135oC.

 

While the LTP range is one of the best weatherproof solutions available, there are other products that may be suitable depending on local conditions.

In conclusion it is unlikely that any organisation will introduce a standard for the term “weatherproof”, so you need to make your own informed decision and ask the right questions.  If in doubt then seek the advice of a reputable manufacturer.

For further information please contact: Flexicon Ltd, Roman Way, Coleshill, Birmingham, B46 1HG. Telephone 01675 466900.  Fax 01675 466901. Email sales@flexicon.uk.com.  Web:  www.flexicon.uk.com.

 


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