Protection by Design: are IP ratings everything?

As of late, I’ve been having a lot of conversations with people around the concept of protection in harsh or outdoor environments (maybe it’s the time of year!). There appears to be one consistency with many of these conversations and that is a discussion around IP ratings. If you are involved in deploying systems or equipment in an outdoor or harsh environment, then I recommend you continue reading on. I hope that through this article I can impart some useful information that will help you ensure that you are maximising the protection of that all-important, expensive equipment that is often responsible for controlling or communicating with critical infrastructure. After all, nobody wants an equipment failure deep in a tunnel or a communications failure for transport infrastructure deep in the countryside due to water or dust!

The questions I want to address in this short article are:

1. What are IP ratings?
2. Are IP ratings everything when protecting equipment?

Let’s begin – what are IP ratings?

Anyone who has dealt with enclosures will likely be aware of what IP stands for and what IP ratings mean. Just for clarity, IP stands for Ingress Protection. The Ingress Protection is specific to two mediums – Solids and Water. In my experience however, I find fewer people are aware of how the ratings are defined and what they are based on. After IP you will typically find two numbers or an “X”. The first number relates to a Solid object with “X” and “0” being no protection and 6 being Maximum Protection or “dust tight”. Similarly, “X” or “0” equates to no protection from water and “9[K]” refers to the highest level of tested protection. I have put a brief definition of each rating for reference below.

First thing to note here is an IP rating can only apply following a certified testing process. And there are elements within the process that are determined by the manufacturer carrying out the test. Furthermore, the reason I wish to share these loose definitions is so I can show you just how specific they can be. If we take rating 6 from the water ingress protection, the actual test involves the following criteria:

“The test duration will last 1 minute per square meter for at least 3 minutes. The water will be projected at 100 litres per minute at a pressure of 100 kPa at distance of 3 meters.”

Now, what I would like you to note here is that these tests are very specific, following specific criteria for a specific desired outcome – an acceptable level of ingress in relation to the tested rating. The above is as technical as I’m going to get but I promise there is a point to highlighting it and that’s addressed under my next question!

So, are IP ratings everything when protecting equipment?

Truthfully, the answer is no. Do they play an important part? Yes, but, there is more to be considered. Whilst I often hear that IP66 is required as the enclosure will be placed in an outdoor or harsh environment this often isn’t necessary and actually, IP55 would typically be perfectly suitable. If we go back to the test criteria, how often have you seen rain being projected at 100L/minute defined as a powerful jet of water – in all directions. Rain will always fall down and with wind, you would likely see it at an angle – maybe even close to 90 Degrees if you’re like me and are based in Scotland…Equally unless you’re in a desert or similar environment where there could be masses of loose fine particles, you’re unlikely to see any harm from solid ingress.

Now, is I previously mentioned, IP ratings are classified under controlled and specific conditions. As we all know, outdoor and harsh environments are not controlled in a lab under specific conditions. The water will likely not be PH neutral or chemicals could even be present if the enclosure is needing washed down. The temperatures will fluctuate and again, if you’re in Scotland like me, freezing temperatures would not be unheard of!

What does this mean then in terms of ingress protection? There’s a fundamental design element for your typical floor standing enclosure (control panel, IT rack etc) that you would typically use indoors – the seals on the back of doors and vertical panelling are exposed and water is not designed to run-off them. Therefore, if, subject to the above-mentioned water conditions, over time the seals could degrade or crack. For example:

• The water’s Ph is significantly away from neutral or there are chemicals present, this could break down the seal’s structure over time and void your IP
• If stagnant water freezes on the seal, it could crack it.
• If there is an insufficient lip at the door contact point, when you need to open the door, any stagnant water could drip into the enclosure.

So I suppose the logical next question is how do you get around this and thankfully it’s relatively straight forward:

• Ensure at minimum, that a rain canopy, preferably with an overhang on all edges is used to minimise water sitting on top of the seals
• If necessary, pick enclosures with a chamfered lip along all edges to allow water to run off
• Where chemicals are present, choose an enclosure with a silicone based replaceable seal
• If necessary, apply a sloped roof
• If IP rated fan/filter units and outlet filters are used, ensure you have a hose proof hood which covers, at minimum, the full area of the fan

The other side of this is solid ingress. It is often the case that outdoor/harsh environment enclosures will have to consider solar gain and dust and dirt blowing around in the wind. Now to many this can be problematic where heat is a consideration. Whilst yes you can add fans to help with air circulation, please remember that even though they could be IP54 or IP55 for example, they will still suck in the dirt from the external environment and filters could clog up very quickly and could lead to a damaged fan over time. So where possible I would recommend an outdoor cooling unit as this will separate the external environment from the internal environment. Therefore, by design, ensuring contaminants don’t harm your internal components.

Another concept would be to use a double skinned enclosure where either:

• The air pocket travels up to a vented rain canopy where the vents point to the ground on the overhang or;
• The outer skin itself is vented.

This way, you can create a natural chimney ventilation effect where any potential ingress (or condensation) would be caught between the inner and outer wall and therefore not affect your equipment inside.

Although brief and not overly detailed, I hope this captures the concept that whilst IP ratings are important, the physical design of the enclosure plays a big role when placed in an outdoor or harsh environment. Once again, if at least one person takes something away from this and changes their approach to assessing outdoor or harsh environment enclosures, I will be pleased. If you have any questions, please feel free to drop me a comment or a message.

Thanks for reading!

Like what you read? This article was published by Yannick Longbottom. Click here to check out his LinkedIn page and read more Rittal articles!