IP Rated Membrane Vents to keep electronics safe

[robjmcnulty]

Hi,

I am looking for a membrane to go accross a vent in a totem that is housing electrical equipment. This vent needs to be IP rated to about IP67. I found Gore Membrane vents but these are not made in the UK and will take 12 weeks to get here if not in stock. So is there any other type I can use that will keep my electrics safe?
Thanks for your time.

Rob

 

[DesignerGuy16]

I haven't seen any but the Gore yet personally. Not saying there isn't anyone out there, but Gore is probably the biggest and best right now.

I'd work with them to try and figure out how much you need so they can be properly stocked, and you can stay stocked.

James Spisich
Design Engineer, CSWP

 

[robjmcnulty]

Well I think this will just be a one off I dont mind ordering more than I need as we do maintance on them. But they said I might have 2 wait for 12 weeks if there out of stock. Thanks for your reply by the way. I there anything other than the membrane you think I can put over the vent?

Rob

 

[drawoh]

robjmcnulty,

Vent?

IP67?

IP67 is protection from temporary immersion. Is there really a membrane that works at this?

JHG

 

[IRstuff]

Gore's products are based on their patented Goretex material, which is ostensibly resistant to liquid intrusion, but will "breathe."

http://www.freepatentsonline.com/re...=all&stemming=on&sort=relevance&search=Search

You might try searching for "porous PTFE membrane ip67"

http://machinedesign.com/article/porous-ptfe-0308

http://www.dewalindustries.com/porus_film.htm

TTFN

FAQ731-376

 

[robjmcnulty]

I ahve just talked to gore and they tell me that the application of using the membranes might be wrong for my totem. They say that it works using presure and that a sudden rise in pressure will not work as there will be no air flow. Does anyone have any other ideas in which I could use?

Thanks

Rob

 

[DesignerGuy16]

The gore vents should work fine with no direct airflow. The air will naturally escape or suck in depending on temperature and pressure differentials.

The whole point of that style of vent is to equalize pressure so all undue stress is removed from your positive seals. It does not instantly change the pressure from a spike to equal, but it's quick enough allow your main seals to work.

James Spisich
Design Engineer, CSWP

 

[robjmcnulty]

I need air flow to reduce the heat inside the totem as if there isn't there is a threat to the touch screens mounted in it over heating. Thanks for the reply.

Rob

 

[drawoh]

robjmcnulty,

You can have airflow, or you can meet IP67.

How about circulating airflow contained entirely inside your enclosure? No membranes. Reliable seals.

JHG

 

[robjmcnulty]

Yeah air flow contained inside the structure is a good idea. How would you apply this with a reliable seal?

 

[drawoh]

Yeah air flow contained inside the structure is a good idea. How would you apply this with a reliable seal?

A heck of a lot more easily than applying a reliable seal with air flowing in and out of the structure.

JHG

 

[DesignerGuy16]

I'll reiterate that the Gore "vents" are not made for direct airflow. They're made to allow enclosures to equalize pressure between internal and external sources.

That pressure equalization takes stress off of the seals so they can work properly.

You can use these in conjunction with an internal air-flow to distribute internal heat across your entire enclosure instead of being localized somewhere.

James Spisich
Design Engineer, CSWP

 

[drawoh]

Jspisich,

Are you moving the enclosure between ground level and some high elevation like 10,000 or 20,000 feet?

I have designed enclosures, sealed, with breather desiccators to equalize pressure. I was controlling dust, and EMI. An enclosure that is both submersible, and set up to equalize pressure inside and outside, sounds like a serious challenge.

If this were my problem, I would work out just how submersible your enclosure has to be. My reference here describes IP67 as "temporary immersion". Perhaps your customer will agree that some parts of your housing will never be immersed. This gives you a place to install a breather desiccator.

My next approach would be to analyze a sealed bellows. This might not turn out to be a bulky, amateurish kludge!

Failing all that, you are designing a pressure vessel.

JHG

 

[DesignerGuy16]

I work in industrial food equipment, where ambient room temperatures can go from 35 deg F with 0-100% humidity to 120 deg F with 100% humidity in a matter of minutes when machines are washed down.

It's quite a unique and challenging environment. Trying to protect against the elements, and extremely acidic and caustic cleaning agents (1.0ph low to 15ph or so high end).

Which by the way, those Gore vents are oleophobic and excellent chemically. The only issue I have with them, is chlorine cleaners react with the acrylic adhesive such that it loses its stickyness until the chlorine flashes off, then it will stick again. So I'd have to use an o-ring backer to compress an adhesive vent to my enclosure so it can't move.

James Spisich
Design Engineer, CSWP