IP ratings are often misunderstood because of the perception that, if the IP rating number is higher, it must offer better protection than a lower numbered rating.
However, at the higher end of the IP ratings this is incorrect. IP rating standards, such as IEC EN 60529 and DIN 40050 specify 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 specification can best be understood by comparing the methods of determining IP ratings in static and dynamic tests. For static tests items are immersed in a measure of water, whereas dynamic tests subject items to jets of water. 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.
In relation to IP ratings it can be 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 where 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, the Adaptaflex Liquid Tight equivalent conduit system has an IP66 rating, IP67 and an IP68 rating at 15 bar for 30 minutes (an equivalent depth of 150 metres). This affords both immersion and spray approval, making the product suitable for use in both applications.
The long term use of approved and specified flexible conduit systems is important to maintain system integrity of any installation and a strong understanding of IP ratings is central to the correct conduit specification.
There are installations where a flexible conduit system is used to carry cabling beneath water, even flowing rivers. Bearing in mind that over a short period of time that conduit will become buried in the silt on the river bed it is particularly important that the specification 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.