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Commentator

Join Date: Mar 2008
Posts: 78
Good Answers: 2

O Ring Surface Requirements

08/03/2010 1:55 PM

Hi all,

After some expert opinion.

I recently purchased a touted to be top of the line electronic cigarette from http://ggecigs.net/ .. the full ggts-avs

This device has a tank on the top to hold the liquid that is 'smoked' through an small heating element surrounded my a metal wick in the atomiser in the centre. the atomiser is basically a tube with the element in it and a small hole near the bottom and inside the tank.

This goes through the centre of the tank and is sealed top and bottom by clamping nuts holding an O ring.

The top of the tank has a threaded top cap with an O ring just inside the lip.

This tank is sealed to obviously stop the juice draining out when the device is not in use. My belief is that this tank is supposed to also be sealed from the air so only a small amount of the juice is allowed to enter the atomiser when suction is applied to the top of the atomiser by the user sucking on the device. A control ring below the tank can be adjusted to regulate the flow into the atomiser bottom.

The rest of the device consists of an overflow tank below the atomiser and a battery chamber with power switch, pretty simple device.

My issue with this device as purchased is that the top O ring seal surface has a shallow remnant of thread through it where it appears the machining is insufficient to totally remove the thread and provide the correct mating surface.

A picture of this groove is here, the O ring (0.8mm) sits within the top 1.5mm of the tank top.

http://i794.photobucket.com/albums/yy227/stonemull/whirlpool/AVStankthread.jpg

My issue with the manufacturer is that the groove should not be there, his solution is to pack out the inside of the O ring with teflon thread tape, use a larger O ring and apply vaseline to the O ring. Not to fill the groove but 'for the O ring'.

I informed him that the O ring seal surface should not have this visible thread in it. His counter was that is what O rings are for. Estimations on the groove are that it is 0.2mm deep.

Now I can't find any specifications for what an O ring can do in this situation.

Is the act of applying vaseline, thread tape and jamming a larger O ring in acceptable in any way shape or form ?

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Commentator

Join Date: Jan 2010
Posts: 70
Good Answers: 4
#1

Re: O ring surface requirements

08/03/2010 2:34 PM

The O-ring, stoney, is there for the purpose of sealing, preventing the liquid from leaking out, as you have diagnosed yourself. Now if nothing leaks out, the seal is doing it's job and never mind that "groove." Does it leak from anyplace else, like the atomiser? Does the whole gadget work well. If it does, what is the problem... where is the beef? There is an old saying among British Engineers. If it works, don't fiddle with it. It is a very wise saying. And if it does not work, return it for a refund or replacement.

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Commentator

Join Date: Mar 2008
Posts: 78
Good Answers: 2
#4
In reply to #1

Re: O ring surface requirements

08/03/2010 8:47 PM

A simple analogy I can use .. consider a mouses water bottle, the upside down ones with a tube.

You could suck on that tube and will only get a little water, when you stop a little air gets in and you can then get more.

This is how the tank functions .. now drill a small hole in the top of the bottle, all the water will dribble out, if you suck you will get water till you stop sucking.

Does it make a difference if the liquid in the tank is extremely toxic .. I think it does.

This is not raspberry cordial we are talking about.

Due to this air leak, the liquid will drip into the lower collection chamber when upright, it will leak out the top on its side. It can deliver much larger amounts og the liquid than it should.

Does it function correctly .. no, entirely due to the failure of this surface being machined correctly.

Do most users understand how this device functions .. absolutely not. My beef is that the manufacturer knows all these details and yet is selling them in this form uncorrected. Need a correction .. add vaseline and tape.

I am in the process of returning mine for a refund.

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Guru

Join Date: Oct 2008
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#2

Re: O ring surface requirements

08/03/2010 3:38 PM

It sounds like this company has adopted the Bill Gates, "get it half way done and let the fools who buy it fix it for us." business model. Not to imply that you are a fool. I salute your efforts to quit smoking. O-ring failure seems to be a common problem, that they have no intention of fixing.

Quote from the site' "This device is not perfect, please don't expect it to be. It requires a bit of twiddling and may have slight issues for you to overcome. It is for experience users only."

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Commentator

Join Date: Mar 2008
Posts: 78
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#3
In reply to #2

Re: O ring surface requirements

08/03/2010 8:35 PM

Perhaps my annoyance is having some effect, as the site has had a few changes very recently the addition of that quote being one. No mention of fiddling was originally present as it was added maybe 2 days ago along with the removal of a few terms.

Assuming I was to adopt the attitude to fix instead of return, what would be the best method. The tank is too thin to allow clamping in a lathe chuck. The difficulty of performing a suitable repair is part of the annoyance.

I consider the best option filling the lower part of the thread with aluminium solder and scraping back carefully.

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Power-User

Join Date: Apr 2009
Location: NY
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#6
In reply to #3

Re: O ring surface requirements

08/04/2010 6:10 AM

If this device is to help quit smoking(coulnt tell from their website) it would be cheaper to use the patch. I smoked for 29 years and quit on the patch which i only used for two weeks instead of six. If I can do it anybody can. the website for this product is very sketchy and uninformative.

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Commentator

Join Date: Mar 2008
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#7
In reply to #6

Re: O ring surface requirements

08/04/2010 8:24 AM

I used the patch for a few weeks and became hyper sensitive to it.

I have been using these ecigs for around 3 months now and not had any normal smokes at all, not a puff since May 9th.

The vapour used is the same as in fog machines, glycerine basically.

So far all testing have failed to show any negative health aspects to using these, so there is no compelling reason to stop using them.

Its like smoking with most of the danger and cost removed. Due to the savings made by not smoking these devices can sell for a reasonable amount and many of us 'vapers' have quite a collection of various types.

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Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

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#5

Re: O Ring Surface Requirements

08/03/2010 10:53 PM

You're right; O-rings are meant for sealing to properly sized smooth surfaces, not for threads, machining remnants, or other roughness.

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Guru
Engineering Fields - Aerospace Engineering - Member United States - Member - Army Vet in the aviation industry

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#8

Re: O Ring Surface Requirements

08/04/2010 9:12 AM

A specific o-ring requires a specifically sized and shaped groove or recess. This is to ensure that the correct amount of compression is applied to the o-ring on assembly and that it conforms to the groove correctly. The correct amount of compression ensures that the optimum sealing for the design is applied.

Somewhere, at home, I have a set of charts that delineate groove sizes for specific o-ring part numbers. We, in the machine shop I worked in at the time, used these charts for a variety of aerospace applications; face seals, shaft seals, etc. I'll see if I can find them, scan them in and make them available for this thread. The o-ring manufacturer should also be able to provide this info.

Any kind of irregularity in the groove is going to be detrimental to the sealing action that the o-ring is designed to perform. It may not be readily apparent and may not even cause an immediate leak but it does compromise the seal, particularly if the part is regularly disassembled. One small nick in the o-ring can render it useless. Twisting the o-ring on installation can also destroy its sealing action.

Also, depending on the o-ring material, vaseline (petroleum jelly) is a no-no. It can break down the material in short order. A (very) light coating of a silicone based grease is more often used. Anything else can also compromise the sealing action. The o-ring manufacturer should be consulted for proper lubrication.

Thread tape is counter-productive. O-rings are not interference threads. Putting a larger o-ring in than a design calls for will also be detrimental. O-rings are a precision sealing device and should be treated as such, not requiring "fiddling". This application almost sounds like it would be better served if teflon tape was applied to the threads and the o-ring left out all together.

Hooker

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