What exactly should one expect from an IP56 rated enclosure - Page 1
Forum section: electronics / projects

author: DTJ
author_rank: Super Contributor
timestamp: December 20, 2024, 02:53:56 am
content: I've got some IP56 rated plastic enclosures installed in a protected area - inside a pipe fitted with a metal cap.This is installed out in the weather (Australia) so temperature could be -5°C up to 60°C with rain and high humidity at times.The enclosure is completely shielded from the elements - direct rain or sunlight cannot hit the enclosure.We are seeing some moisture ingress.IP56 says its completely protected against water ingress with jets of water from any angle. It does however state that limited dust ingress may occur.Does this mean some water ingress should be expected as well?

author: wilfred
author_rank: Super Contributor
timestamp: December 20, 2024, 03:25:03 am
content: The water is coming from humidity and the temperature changes drawing in and expelling air from the enclosure as the enclosure contracts and expands. If water is not directly contacting the enclosure it has to be in the air.Maybe try something in the enclosure to absorb the moisture.Do you have cables entering the enclosure? Cable glands might be another point of entry.

author: Gyro
author_rank: Super Contributor
timestamp: December 20, 2024, 10:50:56 am
content: Water vapor ingress via the interior of cables is a classic issue with temperature cycled sealed enclosures. It is sometimes better to manage the pressure variation directly (eg, a tiny breather hole at the lowest point of the enclosure (obviously I don't know the exact usage situation).

author: DTJ
author_rank: Super Contributor
timestamp: December 20, 2024, 01:29:49 pm
content: Quote from: wilfred on December 20, 2024, 03:25:03 amWe are working through the connectors and ensuring they are all sealed. We figured its 'pumping' its way in with temp cycling.

author: DTJ
author_rank: Super Contributor
timestamp: December 20, 2024, 01:31:13 pm
content: Quote from: Gyro on December 20, 2024, 10:50:56 amYeah we're looking at a goretex vent to manage the pressure changes. A vent should keep the dP to zero or close enough. Thanks.

author: Siwastaja
author_rank: Super Contributor
timestamp: December 20, 2024, 01:41:32 pm
content: Also if the device is low-power, you can't avoid hitting condensing conditions. Like, you know how sometimes every surface in the nature, grass, car windows etc. frosts, and you don't even need 100% RH for that, humid air (even say just 80% RH) getting in contact with a surface which is cold from stored thermal energy is enough.So you may need to put a heater in it; not a problem if it's mains powered. Probably just 1W or thereabouts is sufficient: something that heats up the entire air within the enclosure by about 5-6 degC.Another option is completely sealed, but that means significant pressure differences will be generated. It's not very easy to do; a breathable design is way easier but downside is it breaths humid air in, and you need to heat a tiny bit so that you never hit the dew point.

author: peter-h
author_rank: Super Contributor
timestamp: December 20, 2024, 03:05:59 pm
content: 100% watertight is IP68.Then, as stated above, you need to deal with the connectors. Gases and liquids will travel along cables, for amazing distances. I've seen heating oil travel some 50m, and slightly uphill via capillary action, via a multicore cableSo even with the right connectors, both ends of the cable need to be either sealed, or both assured to be dry.You will get liquid water (100% RH) anytime the temperature meets the dew point (that is where clouds form in the sky, in simple terms).I tend to chuck a big bag of silica gel into the enclosure and that should absorb water for a year or more if it is sealed well.IP68 boxes are not dirt cheap, because they need to be rigid to ensure there is even pressure on the o-ring seal.Done this many times