Waterseal Design

Hay is for cattle. What is a waterseal container? Aquarium sealer seems to work well on waterseal containers that hold fish.

In general I do my own design work. Then I know why material choices are made.

tnx

English is not my first language so I'm sorry for misspelling. Basically I need to design a container that need to hold the screen in it and I need to make it waterproof so everything in the container won't get wet. The container itself made of ULTEM because of other specification.

Silicone aquarium sealer.

It's not suppose to be permanent seal, I need the option to open and close it. how about O-ring and what do i need to plane for it? (diameter, material ect.). i need it to be in 5 meter depth.

You didn't say non-permanent in the beginning. Are we supposed to read your mind???????????????????????????????????????????????????????????????

I'm not going to do your job for you. Hire a designer.

DO YOUR OWN WORK!

i'm sorry i didnt say that, i shold have say that. i'm not asking you to do my job, i'm asking about the general option of how to water seal 2 surfeces and how to seal container.

If you have nothing to say then don't say it.

Probably can't google a design!

If you have something to say, SIGN it. Hiding behind "guest" shows your colors.

Have you not had your coffee this morning?

There is no rule on CR4 that says "Do your own design work". C'mon, chill. He's asking us... the "experts"... for ideas.

If you can't say something nice...

Experts are use to the idea of being given respect and/or payment for their experience.

Gee... that'd be neat.

A cogent explanation of the problem at hand would go a long way toward getting help. OP gives no details. At that point a zip-lock bag is a fine solution.

If you can't describe the problem, how can you expect an informed solution?

I'll try to make nice.

Cheers.

well... silicone caulking (or aquarium seal... same sort of stuff) is an excellent suggestion, and it doesn't have to be a permanent.

Suppose you have a hinged glass plate... and you want to effect a seal to a flat surface that the plate will land on. Create a heavy bead of silicone on the flat landing surface, and let it cure. Then, take a razor blade, and create a rolling mechanism, and use that to cut the silicone to a uniform height... Now when the glass lands on the silicone, it will have a good interface with the glass.

Alternatively you can purchase some neoprene (closed cell foam) adhesive tape, and apply that to the landing flat.

The choice of gasketing you choose is depending on the quality of seal you need. If this is going underwater, then foam will not stand much pressure, and you need to engineer the seal in a different manner (not flat)

hope this makes sense.

good luck.

Chris.

ps.. you are getting aggravation, as most people around here don't like 'homework' questions.

If anyone can possibly be harmed by your design, then it is highly advisable to hire a professional, or don't tell your insurance company that the system was designed by a non-professional.

Welcome to the world of real world engineering. You've had over a dozen years of schooling now. Every question previously asked of you could be answered directly from a textbook or an analysis of that text. Now you have been given a simple task that does not exist in a text book. A process you should have learned along with your schooling is that you will now have to go through the iterative process of design, test and verify until you find product that meets your criteria. I suggest that you do your testing with something less valuable than your TV screen in the container at first.

We do not know all of your critical criteria for these containers. I suspect that you do not know it either. But you should have faith in your own skills. You will likely not get this done on the first try, few have succeeded on their first engineering attempt. But all of us after stumbling have analyzed the failure carefully to improve the design.

Most of us here get paid for our engineering skills. Those who come here and show some initiative and knowledge of their engineering field find that this community helps each other as a member strays out of their engineering comfort zone. Right now none of us know what your engineering capabilities are. Some individuals here can even become very nasty when a moocher arrives to just take engineering skills from us and not return anything to the community. This is why I hope that you are a recent graduate into the school of hard knocks.

Oh, my field of expertise is not mechanical design. But unless you have a battery driven TV that has a stored video to run you, will need to get power and signals into your box. So other than the door and/or viewing window as possible leaks you will also have these additional connectors. You will also likely need some water tight switches on the outside so that a diver can change some settings on the TV. You may also have to consider the heat dissipation that will happen inside the box.

Welcome to the madhouse.

tnx for the support. i didn't learn that in my study, and i'm still a student. i'm done with the waterproff switches and connectors, and i got battery inside already (it's for a 6'' screen). all i need to know now is the options to seal contact between 2 surfeces (the screen and the top) and how to seal the top and the bottem.

Good answer. Nothing is easy!

Basically this will involve some kind of gasket (an O-ring can be considered as one type) and flanges, with fasteners spaced closely enough to minimize flexure of the enclosure. A NEMA-6P or IP68 enclusure with a clear polycarbonate cover might be available as a factory item.

You seem to spoil the fish by letting these watch TV. You can also fish with a regular lamp, though you will go straight to hell for hell. What about a cheap ZIP Lock bag? You will hear the sound better there. Used to take my camera in one under water.

5 m depth is roughly 0.5 bar or 7,25 psi.

Calculate your surfaces and you will find how strong everything is supposed to be. Show us what you already have in mind and we will pick it up from there,

NOT the solution what you specifically asked for.
You could however use a clear vacuum pack bag.... simply place the tv inside and remove the air.

Sounds like a "rock clip" special effect - paint the screen chroma key [blue or green - not red as it spills or dies underwater] and tell them to super the screen image in post.

Aside from that; I hope this is an ELV LCD not a CRO you are thinking you will get water (and pressure) proof.

I thank you all for your advices. The solution I came with so far is this, I make in the top part a frame and I push the screen on it with a rubber between them. This is how it's look like in general: what do i need to think of if i'm going with this solution? The contact between the top and the bottom parts is still a problem. O-ring maybe?

5 meters of water column would exert 0.5 kg/sq-cm. So please be careful that this pressure do not deform the screen (in case of LCE) or cause an electrocution (in case of LED, very high voltage involves at the back of tube)...

As best as I can remember it, this is how that old system worked (section view)... the only other thing was using silicone in the rivet holes before riveting. (and saliva afterwards to smooth it out.) the backing of the lower section was fiberglassed in to form the back sheet. (lowest) The Tedlar and Teflon sheets wer attached using 3M double sided tapes. (and then we used a a large oven to tighten the sheets up and a heat gun remove wrinkles. The Tedlar is very tough.. almost bullet proof. I'm not sure about the sheet metal.. might have been 14 ga.

If you found a 3M tape that sticks to a sheet of teflon, that would end a lot of grief for a lot of people. In my experience, I haven't found any adhesive that would adhere to teflon. The "ok, so now how do we attach the teflon" conversation is one I've had several times over the years.

LOCTITE 770™

Hm... well that question was sort of rhetorical, actually. I'm pretty darn sure there is no adhesive that is able to secure PTFE. No bond stronger than you could break with a single finger, in any case.

Ho hum

^{_{<note to self; do not try to broaden Out of the Box's Experience>}}

LOL ... i wasn't dissin' your input... its just that I've had extensive experience with PTFE, especially in regard to adhesives for it. I worked an entire project around that particular issue. And yes, I have tried that LOCTITE. It's been suggested before. It might be the best thing to use of anything available, but no... it really doesnt work as far as holding up to any shearing forces worth mentioning.

It might hold a hood ornament on top of a teflon car driving down the road... but if a bird hits it... it's gone.

Too long in the box, I guess? I had to re-lathe the inner part of a shaft that had been glued wrongly. A 20 mm finger breaking piece. Applied properly?

I haven't used it in a shafting application. I was referring to two flat surfaces. I could see that it would likely fare better if you were using it on a shaft in a hole.

The teflon sheet I'm referring to was like saran wrap.. very light, heat shrinkable, and excellent thermal characteristics, as well as UV resistant (same for the Tedlar) It was perfectly transparent, so not like teflon tape. (white)

this design created a captive airgap that insulated, and also helped prevent condensation issues.

but I don't know the product for the tape or the teflon.

but 3M has an applications department that lives to help customers with their applied problems. (I worked for 3M tape and scotchbrite a few years later)

Chris

I'm fairly sure this is the teflon product. it was definitely DuPont, as was the Tedlar.

As for the 3M tape... I don't know.. would have to talk to the specialists. this is in the ballpark. I remember it being 'pressure sensitive' and being 1" wide, as it fit on the 1" aluminum frame. the teflon was able to be peeled off... so it wasn't a great bond.. but it stuck well enough to be heat shrunk... and the we had the mechanical compression from the strip that was pop riveted that would help keep it all in in place. With the Tedlar, that couldn't be removed from the 3M tape after bonding and heating. We had a special roller for applying pressure that used something like a pair of skateboard wheels, with just under an inch between them (adjustable) and then it would really stick the tedlar down... (and teflon enough)

anywho... that is all I remember.

what if i take you disign and change it abit. will it solve the problem with the screw? this solution can help me with the top/bottom connection

Avisar, you may want to chamfer that bottom corner of the more densely hatched object in your drawing. What you have there is a square shaped gland to hold your o-ring. You'll do better with something with at least one of the walls being sloped. I would diminish the gap above your o-ring, and then chamfer the bottom corner so that the o-ring can compress and deform somewhat and be partially pushed into the acute angle formed by the chamfer.

how much do i need to chamfer? if i'm taling about 2mm thread dim. O-ring

At this point, I'll just suggest doing some basic research on "O-Ring Gland Design"

Learn the theory and the compression ratio's and the logic behind choosing the proper o-ring cross section and even the proper o-ring material and durometer. Basically, you want the o-ring to take on a slightly triangular shape, as it is compressed into the gland. Much more to it, than anyone could tell you here.

This will be information that you are likely to use again in the future.

Good luck.

About the O-ring research you're right and I'm on it, the problem I have with it is the way to use a O-ring, I know the way I did it is not the only way but I can't fine a place that I can look for it that how I discovered this forum. for anyone how read this after and want to find "O-Ring Gland Design" information visit here tnx btw , how do i skip line in here? it's irritating me that i'm writing all in the same line

The PARKER O-RING Catalog is an excellent resource for learning about o-ring usage and gland design. Some of it you can find on their website, but I recommend also asking them to send you the hard copy. It's a great reference. It will become your o-ring bible (or o-ring koran, perhaps in some cases)

Parker O-Ring Handbook

tnx for the handbook. i'll get into it right away. but what about the design so far? and yes, this is a millitry use.

In that case, I wouldn't be thinking of using a circular thing to seal a big square hole, in mass produced moulded plastic, especially if the sealing face is not in 'line of draw'.

Or at least you should be thinking o-ring 'gasket' design - not 'piston' or 'rod' seal.

what problem with the screw? you mean the one mentioned by 34point5?.

not really a problem, and as I said, my solution is oriented towards high water pressure situations.. aka complete immersion.

The type of seal you are showing is not typically done as it can shear material off the o-ring, and/or be difficult to assemble. (especially without that chamfer) and there is no allowance for o-ring compression... so no I would not suggest that.

Please give more background about what you are trying to accomplish, and what the environment is. Is this a one time application, or are you designing a product for production?

Chris

This is a product and hopefully for mass production. The product is a 9" reinforce glass LCD screen with buttons to control it, the screen is part of the sealing. It's suppose to hold in depth of 5m (1.5 atm if I'm not mistaking) The screen and the electronics need to be in a box that made of two parts – top and bottom. There is 4 places that need to be sealed, this what I have so far. seal for buttons to control the screen (fig.1), cap that screw in (fig.2)(there is screwing in both sides, i put only in one side), around the screen (replay #14) and the top and the bottom contact(repaly#28). the sealing is not permanent (need to open and close the box every now and then). Right now I have problem with the screen seal and the cap seal (I don't think it will hold) so I need other ideas or information. The box made of plastic (ULTEM).

you said 'waterseal'... so does that mean that it must go completely immersed.. underwater... or just the occasional raindrop??? this makes a huge difference in the design. Is this a military application?

Chris

It sounds like he wants it immersed 5 meters under water.

I see that now.. thanks.

I regularly deal with water pumps that are assembled similar th this design. The two differences are 1) There is very little air gap between the two parts in the area above the O ring, and 2)The area for the O ring to reside in is a triangle. Leave the bottom of the existing O ring groove, but run the chamfer at a 45 degree so it intersects the upper part at another 45 degree angle.

If I could draw like Chris, I would have a much shorter post. Good luck.

Use a tubular design and thread the shafting so the top and bottom sections are contiguous (for strength) slip the monitor in and lock it into place with a clamp, backing or brace.

Use O rings on the threaded shaft and add silicon lubricant to maintain rings and improve seal!

That should give you at least 1 Atmosphere capability (14.7 psi or 33 ft)

Cheers

i thank you all for all your help and patience!!!