Applying IP ratings to flexible conduit

31-10-2017

Ingress Protection or IP ratings are often misunderstood and applied incorrectly when it comes to flexible conduit. Meirion Buck, Senior Design and Technical Manager for Adaptaflex – a brand of ABB – explains how the ratings work.

Conduit selection is a serious matter, often fire protection is considered the main specification criteria in conduit selection. The fact is, all conduit systems must comply with international conduit standard IEC 61386. Amongst the properties needed for this approval standard is ingress protection or IP ratings against solids and liquids.

However, at the higher end of the IP ratings it is not always so clear cut. ISO 60529 specifies how products should be tested and define the particular test for each rating. The standards also clearly explain the meaning of each individual IP rating.

The variation in the specification can best be understood by comparing the methods of determining the IP ratings to static and dynamic tests. Static tests have the items immersed in a measure of water, whereas dynamic tests subject the item to jets of water.

Testing procedures

Dynamic tests vary quite considerably; an IPX4 rating is equivalent to water from a garden hose at typically 10 litres/min for five minutes through 180º, whereas an IPX6 is closer to a fire hose delivering 100 litres/min for three minutes. 

On a typical Ingress Protection rating, say IP54, the first number stands for the protection again dust and solid objects, while the second number stands for the protection against liquids. In this case IP54 means, 5 - protected against dust - limited ingress no harmful deposit; 4 - protected against splashing water through 180º - no harmful effects.

The tests, up to IPX6, are carried out on a static product where the water is either splashed or sprayed around the product under test. The intensity of the water test ranges from falling drops of water through to a powerful spray jetted on to the product from specified angles. 

The water test conditions are very specific within the EN 60529 standard, defining water flow rates and duration of test. Even the diameter of the water jet hose nozzle is specified along with the distance from the test piece. For IPX6 the flow rate is 100 litres per minute for duration of at least three minutes.

IPX7 and IPX8 use static tests, conducted by immersion in water. IPX7 test is temporary immersion. This is a pre-set depth of one metre and a pre-set time of 30 minutes. During the test there should be no ingress of water to cause harmful effects.

The continuous immersion IPX8 test, is set against a pressure and a time agreed between manufacturer and user. Again, during the agreed period, there should be no ingress of water in quantities sufficient to cause harmful effects. The test has to be more severe than the IPX7 test.

For IPX8 the test states - ‘protected against long periods of immersion under pressure'. Hence the result of the test should be specific and clearly quantified. For example, IPX8 15 bar, illustrating that the product has been tested at a depth of 150 metres of water for a specified time.

The test against IPX8 the pressure rating must be clearly stated to clearly indicate the depth of water at which the test was carried out. This is standard practise on cable data and clearly indicates the operational capability of a product. For example IPX8 15bar 30 minutes.

The German DIN 40050 standard for automotive use, has an IP69k test, which typifies installations on vehicles subjected to pressure jet washes. This involves spraying high pressure water at 60° to 80°C at angles of 0, 30, 60 and 90 degrees at between 10-15 cm distance.

In relation to IP ratings it can be clearly seen that spray tests up to IPX6, are quite different to immersion tests for IPX7 and X8. Indeed, products that have IPX7 or IPX8 may well fail the IPX6 test, as the jet of water can, in some cases, force its way past a gasket or seal that protects well under static loads when the weight of water is helping to compress it even further.

For this reason, Adaptaflex uses dual ratings for ingress protection for its high IP systems. In this way conduit users have all the facts about whether a conduit system is suitable for use in direct jet spray and/or immersion applications. For example, Adaptaflex's liquid tight conduit systems have an IP66, IP67 and an IP68 rating at 10 bar for 30 minutes. This affords both immersion and spray approval, making the product suitable for use in both applications.

Application suitability

Specifiers should always consider the system – not individual parts as the IP rating is always applied to the system. Conduits themselves have no IP rating until a fitting is applied. Remember also that systems should not be mixed. Never use conduits with fittings from different suppliers.

Whatever the application, the product has to be fit-for-purpose and it is a responsibility of the specifier or electrical contractor carrying out the installation to ensure the product meets the requirements. This they can do by checking with the manufacturers that the information being given is correct.

So, the higher the IP number does not necessarily mean the better the performance as clearly defined by the spray and immersion tests. Clear knowledge of IP ratings means you can apply the most economical solution, designed to meet the requirements of the installation and fit-for-purpose.