It sounds like you are operating the valve outside of it's performance parameters.  Some valves cannot operate with bi-directional flow for example. Is this perhaps part of the problem?

Hi,

Get hold of a copy of BS-4518,METRIC DIMENSIONS OF TOROIDAL SEALING RINGS,'O'RINGS & THEIR HOUSINGS.

Your problem will be solved.

Cheers!

                                            

To Atad:
Yes, it's possible that I use this valve outside it's default parameters regarding speed of gas flowing through it. Regarding direction of flow, there should not be the problem IMHO. Even if flow is too fast I have to do something to make those valves work. So It would be best if I have some guidelines for designing those types of valves.

To Cranekiran:
all hapy that I will solve my problem I made google search with caption that You typed.
Only link that I get is: http://www.dstan.mod.uk/data/66/014/00000400.pdf  ;(about 80 kb), but look's that this is not what You refering to. Is that book, standard or something else ? That caption to me thoes not ring any bells. PS: I'm located in Europe.

BS 4518 is the British Standard for Metric O-Rings.  You could also look at BS 1806 which is the Britsh Standard for imperial O-Rings or ISO 3601 which is the draft standard for Fluid Power System O-rings.

One other thing that may help you.  Take a look at www.icrank.com.  It has an O-Ring design program that you might find useful.

Hi,

I don't think you can find BS-4518 in any search engine.

it is a standard (BS is for british standard)for 'O'rings which has to be bought from the concerned institution.

Still for your help,Refer this sites:-

http://mdmetric.com/or/gb01.htm

&
http://www.azom.com/details.asp?ArticleID=504

The above info. is just to guide you what the standard refers to,But as I mentioned you will have to buy it to understand it for your purpose.

Bye!

Thank You all for reply's.
Great links, I have found a lot of info on various things .. great, great stuff ..

Calculations for O rings is not realy what I searching for. I would like to see some cross section's of various 5/3 valves, and specialy 5/3 valve with O rings.

Sorry if I'm bugging You, but I'm relativly new in this area, because those valves that I have are just one small part of bigger device. Best regards to all ..

Hi,

Can you send some picture to this thread if it is possible?
I can basically think these are the reasons now:-

1)First is the 'O'ring design.

2)What is the rated pressure of your valve?

3)Some petroleum jelly & lubricants actually affect the physical properties of 'O'rings.I hope you are not dosing the inside of your valve with too much lubricants.

Also,you can disassemble the valves & check for dimensions(qualified vs rejected).

Finally,you have not told us what kind of valve is in question.

Cheers!

I think that is not possible to upload files here, so I created FTP account, and picture can be found here: http://snapyy2002.freewebsitehosting.com/Valve%20ilustrated.jpg

1) I know that O ring design is not best solution, but I have to maintinance those old valves .. If I colud make some not to complicated modification, that would be ok ..

2) Working pressure is around 8 bar, but it can be up to 15 bar

3) O ring's and lubricants are from silicone. I think there is not too much.

4) I have disassembled valves, but I have not original dimensions. Manufacturer is unknown, and that is why I would like to se how to define those dimensions. With standard calculations for selecting O rings (from www.efunda etc.) I have same problem.

I think that problem is that air on starting to open valve, flow too fast and suck out O ring like illustrated in picture.


Any ideas ?

Well!

Your thread is really a challenge to me.There are some suggestions:-

1)Why don't you increase the groove depth & width to fit in a larger dia. of 'o'ring?

2)Can you regulate the flow of air before it enters your valve?

3)Can you fit in a spacer ring to press your 'o'ring in position?

4)Can you fit in multiple 'o'rings after machining multiple grooves?

I can only think of the above only,Also,I was not able to see the picture you provided due to some web-problem.

In any case I would request other members to provide some answers too.

Bye!

Thank You for the tips ..

1) We have tried to increase groove depth, and it looks that this helps a little. Groove width is not possible to change.

2) There is no any regulation of flow. Gas is geting out od cilinder at 8 to 15 bar without any resistance (that is condition)

3) Yes, spacer ring is possible, but what we have made is new elements with adjusted groove widths, so the O ring is axial compressed for 0.3 mm (O ring diameter is 2.5 mm)

4) I don't understend what do You exactly mean with this ? How do I put them together ? One next to the other in axial direction ? There is no room for that.

It would be best if I can post picture somewhere, because I think that would be best explanation of problem. I'm not realy working in this area (valves), so it's a little dificult to describe problem. Is it possible to send picture to You over e-mail? If so, You can contact me on snapyy2002@yahoo.com

Best regards

O.K,

Mine is :-

sankey_sank@yahoo.com

Also,Are there any experts in this thread in this type of valve?

Bye!

The problem you're talking about is called extrusion.  Designs in O-ring handbooks are not made to handle this use of an O-ring.  My company makes this type of valve and I can't get into the details of how we handle this situation without violating proprietary technology.  What I will say is to try putting a lip on your groove to make the O-ring captive.