Breather Valves & Flame Arrestors

Well (really basically), a breather valve is a special gland which allows an enclosure to, well, breathe and equalize the pressure inside the enclosure with air outside the enclosure. Has a filter that does this. Good for stopping moisture forming and gas buildup inside an enclosure.

And similarly, a flame arrester prevents the flames from an explosion inside an enclosure from reaching the outside of the enclosure (well really it just allows the flames to cool to a safe level that won't cause any gas outside the enclosure to go bang.

There are other types and uses but these are your two basic types for electrical enclosures and hazardous area enclosures in this part of the world, and as you have given very little info i'm guessing these are the types you are talking about. If not then I cannot help you.

Try doing a search on the web.

Breather valve - think pressure equalization - it avoids delta press with regards external pressure to avoid explosive combinations

Flame arrestor - think can inside a can. Two controlled aras, where combustion within one will smother the other

Got it? Good

Breather valves can be used to prevent build-up of pressure or to allow vapour separated from liquid to escape. In petrol pumps the air separator allows gas to vent but prevents liquid petrol leaking. The vented gas, (flammable) then passes through a copper-mesh gauze filter which will prevent any flame getting back down the pipe. This is the principle of the miner's Davy lamp - the metal gauze cools the flame on one side of the gauze and prevents it crossing to the other side but allows vapour to pass through. (the Davy lamp flame changes colour in presence of flammable gas!!).

Electrical terminal boxes used in flammable atmospheres do not have seals around the lid so that pressure doesn't build up inside but the metal faces are close enough together to snuff out any flame and stop it escaping.

Some of the above seem to be more geared toward electrical, so I will throw in my two cents on Chemical.

Chemical engineers often use "breather" valves, or we like to call them "blanketing valves". These have a inert gas fed to them to keep air out of a storage tank. There is a HUGE amount of information on these valves and the flame arrestors that we use to keep a flashback from going inside a tank on this web site:

http://www.protectoseal.com

Also, they have sizing software - which I think you were looking for.

Hope that helps.

Stephan

What you're calling a breather valve is probably what is commonly referred to as a Pressure/vacuum safety valve. Allows vapor to vent out on filling a tank to avoid pressurization and air to breath in on emptying to avoid tank collapse from internal vacuum. Sometimes introducing air is a bad thing so you substitute inert gas - If you do you should have a back up (redundant). The most common type of flame arrestor is indeed a heat sink.

Most of these devices are constructed of aluminum so excercise caution when cleaning with sodium hydroxide.

Check this site - they manufacture tank breather/flame traps

http://www.tenob.co.nz/breather.htm

This South African engineering company also manufactures Breather Valves or Pressure Release Valves: http://www.breather-valves.com

need to calculate the breath in and breath out capacity of Automatic breather valve dia 6" installed on HSD tank ? thanks and best regards JH