Waterproof Enclosure Design

hi Marky!

There are many polymer systems, which would fit your PROBLEM-NEED. However, I may add that mere selection of so-called water resistant Polymer/ Plastic/ Elastomer would not solve your problem as many other parameters are involved in actual application level. Answering correctly your problem would need correct engineering, and this would need that your EXACT specifications, including contour data and your present construction methods ... I feel if you could enlighten these through either FULL and clear explanation or through detailed presentation/ drawings, that would facilitate analysis and redesign. If you feel it is worth, you may contact me..

That post before mine looks like he's looking for business. We use Polypropylene for our hydraulic tanks and it works, ok, so-so.. but we are changing to liquid nylon 6, that's much better, and hard enough to crush an o-ring.

You didn't say how much heat that light puts out, anything over 180F is going to be a problem. Be sure you ask your supplier for the temp. rating.

Hello Labyguy, While I appreciate your concern for commercializing discussion matter under subterfuge, please do take note that all persons may not be of that category. Please also try to study the details of my personal profile, and I hope you will further appreciate that these technical interactions are not needed for my personal business. The different data requested are needed for definite and detailed study from a DESIGN angle, and yourself being a manufacturer or supplier of such product systems, would also be well aware of these!

I still continue to hold my original request unchanged, which if the questioner is interested, may decide to respond or not

With best wishes..

Labyguy, thank you for your reply. Do you have any permeability figures for 'Liquid Nylon 6' as I cant find any data on the web.

I do have detailed drawings but am loathe to send them to anyone that I dont know. Please do not be offended.

The design at present has 10 bolts clamping the flange of the PP back box between a pressed Stainless Steel ring and the Machined casting that is the front Bezel. The O ring is clamped between the PP and the front Bezel.

As the light source is LED, the power input is relatively low. 180F is not a problem.

Can anyone suggest an Elastomer for the O ring material with a low coefficient of permeability please?

Hi Marky, may I suggest that you visit this site: www.solvayadvancedpolymers.com you will get all technical and other data on some of the best polymer materials you are looking for, including elastomers

place a small schrader valve and cap on it. Pump it up to 5 psi and close the cap tight, place it underwater and see if it bubbles. 5 psi is enough for 10 feet underwater. Positive internal pressure will block leaks. The scrader valve will add 25 cents to the cost and give you the ability to test each item for pressure proofness.

If you need higher pressure, make sure the design will tolerate this extra pressure.

Be careful here. I think a schrader valve can also act as a check valve if the outside pressure is greater than the inside pressure it will simply open...not water tight any more. I only know this from experience...many times I have filled tires with only an air gun as I could not find my air chuck.

Rubber other option Rubber there are a number of different ratings for rubber O rings dependant on heat and they come in all sizes and various forulas that are reistant to chemicals as well. Just go along to your nearest pump company and they should be able to give you al the advice you need. Also the cable use should also be rubber. Siemens make very good flexible cables that are designed for permanent immersion Hydrofirm and Oxoflex Plus. Or just Google O rings

Hello Marky,

There is a unique product that may serve as a back-up for combating ANY moisture getting inside your light, once you have selected the best o-ring seal, etc. Moisture Absorbing Compound is a soft gel like substance that comes in a 10oz caulking tube. The unique thing is that it is hydrophilic and BONDS to water very quickly creating an even greater "seal" as contact with more water occurs. The product is currently used inside electrical enclosures and conduit leading to them to keep moisture out. It does not melt or freeze and stays in solid form once bonding to water has occurred. If a bead was used on the inside of your seal prior to assembly it would be an excellent secondary measure.

Hi Marky,

What about epoxy? It's very strong and seems that it would have very low H2O permeability. Maybe something to look into.

Mike

Thank you everyone for your replies. I have been doing further research.

Aurizon - your idea about fitting Schraeder valves and pressurising the units. I was caught out using a similar idea to pressure lamps for leak testing. The gasket arrangement behaved differently when pressurised rather than a force the other way which water at depth presented to the lamp.

I am intersted in the moisture absorbing compound. Do you have a name for it please?

<Does anyone have any advice on materials / processes that I could use to stop these light fittings filling up with water please?>

Encapsulation inside a translucent solid?

there is a need to cap and seal a shrader valve used this way, and that will stop in/out water flows.

Another thing, you can also fill the insides with a clear fluid that does not misce with water and is a nonconductor. The use of solid state LED lights in such a fluid will prevent any collapse under pressure and the fluid will dissipate heat as well.