Water Tight, Air Permeable Venting Option

On the deck of a boat this is known as a "Dorade Box" - it lets in the breeze and keeps out the seas. Google away, there are plans, or plenty of ready - mades to buy. What is a NEMA4X ?

Re: NEMA 4X, try http://www.trackballs.com/NEMA.doc

What is it you are really trying to do here?? Cause Lapinbleu(990)'s quote is very applicable here: "A problem, properly stated, is a problem on its way to being solved". 30 in3 of air in 10 seconds isn't a great deal. With a few years at sea, a dorade vent does work, but I think we're talking some lind of electrical service situation?! Let us know.

NEMA 4X is normally related to installations within hazardous area. Free ventilation through the box would not normally be allowed. Standard installation is by use of pressurized instrument air with flow regulator and a calculated small hole so as to allow air to exit. This will not allow other air or water into the enclosure since we would have a higher pressure within the enclosure.

What about placement? Place any type of exended vet in the bottom using a "Drip Loop Theory." Sorry about th anonymous statis my company has changed IP addresses and I haven't figured out how to log in again.

Either "Raco", or I believe its "Hubbell" makes a vent that looks like a 3/4" pipe terminal adapter with an insect guard screen in it. It mounts in the bottom of the enclosure and is listed as "raintight." It mounts in a 3/4" KO (Knock out) if one is provided. Or you can drill your own hole. Your local electrical Distributor should be able to provide you with one.

The 4X NEMA rating adds "corrosion resistance" to the normal, NEMA 4, outside electrical enclosure, which provides protection from rain, dust, etc. I have had experience with corrosive fumes from hot ferric chloride virtually rusting anything ferrous and otherwise corroding other metals in a circuit board etching room. Unfortuantely, the guts contained in a NEMA 4X usually aren't immune to such corrosive fumes, so using any kind of opening in such an environment won't provide the level of protection needed. The only simple solution is to install properly sealed air ducts to the enclosure made of a material that is not affected by the corrosive atmosphere, in which case, a continuous flow of air can be had.

If the air is from a piped in air source, Unless you are using very dry instrument air, you will at least need a desiccant can. Also, if the piped in air is "shop" air, you will need an oil trap. These items will require periodic maintenance.

Hi,

I have a similar requirement. I am not sure about the flow rate, but have a look at the "Breather Vent", listed under "Accessories" on Stahlin's web site (www.stahlin.com). It claims to allow air flow while maintaining enclosure integrity. I am also considering adding 2 thermostat controlled fans (1 in and 1 out) from DDB Unlimited (www.ddbunlimited.com) but am concerned about protecting the inlet and outlet vents sufficiently well enough to keep rain out. Have you found any other solutions?

Regards,

AP