EPDM leaking water

[rc0213]

We have a product that attaches to a truck and is exposed to the weather. We use a EPDM gasket to make it weatherproof. But, somehow, it is still accumulating water. I thought EPDM was waterproof. Am I not correct? If so, what are we doing wrong? Or, is there a better gasket material to use in such application? Does anyone have any suggestions of what is going on, or suggest a different gasket material?

 

[btrueblood]

EPDM will seal out liquid(*) water, if the contact surfaces are smooth and clean, and you give the gasket consistent compression under all conditions. EP will hold up better to weathering and UV than almost any other elastomer. Try putting a little silicone grease on the seal prior to making up the joint.

(*) all elastomers are permeable to water vapor to some degree.

 

[EdStainless]

If this housing is exposed it is possible that just the heating and cooling each day is enough to draw in a little humid air and then condense the vapor.
If you can check the conductivity of the water it will tell you a lot. If the water is salty then you have a real leak, if the water if very clean then it may just be condensation.

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P.E. Metallurgy, Plymouth Tube

 

[rc0213]

btrueblood, that is a good point, and I will make sure we have put some silicon grease on the seal.

EdStainless, the housing goes to an LED light assembly. So, you are correct in that the day and night creates condensation. But, I thought the LEDs would dissipate what condensation accumulates. There might be enough heat from the LEDs that it creates condensation with the right weather condition. What do you think? Maybe it is not the EPDM issue, but that the LED heats high enough in a cold enough weather to create it's own condensation issue in the housing. We did not very good details of how the housing is collecting water, but there is a thought of using a different material right now.

 

[EdStainless]

LEDs generate very little heat, probably not enough to drive off collected condensation.
So the unit either needs to breath freely, or it needs to be perfectly sealed.
Both of these have serious issues.
You need to allow a little breathing, and design a way to handle collected moisture.

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P.E. Metallurgy, Plymouth Tube

 

[MintJulep]

There is a lot more to gasket design than just material.

With the limited information provided so far all anyone can to is guess.

Can you post a picture? The site here just added a neat new feature making it really easy. Us the "Upload Image" button in the toolbar about the reply box.

 

[rc0213]

Thanks, all, for other considerations,

I will keep all those factors in mind, thanks.

MintJulep,

Attached is a back print of the part. I hope it is enough information to clarify any questions. It is a gasket between an LED Light Housing and the vehicle.

RC