The Stovebolt Site Forums The Shop Area The Tool Chest Exterior Black pipe air Lines

I am thinking about running some black pipe from mid garage where compressor is located to the front of the garage about 30' on the outside of the garage. What pros/cons do you experts have?? I have the black pipe and most of the fittings. I live in Upstate NY where temperatures swing 100 degrees between seasons. Your ideas and thoughts??? Thanks prior
Dan

http://www.tptools.com/tech-metal-piping.dlp (a good general-purpose air delivery system)

Maybe someone will comment on black pipe rusting outside a building?

Galvanized pipe/fittings might be more appropriate (but galvanizing material might slough-off inside the pipe)?

Given your temperature swings and the possibility of moisture in the lines, I would be more inclined to run it inside, use a tee to run it through the wall and a drip leg beneath to keep any moisture collected on the inside..

Not a pro... but I'd run it with a drip leg with a ball valve to allow quick/easy purges.

I'm sure there is a code to follow... but I figure if they allow natural gas lines (yeah, low pressure but they go BOOM) outside a house then an air line should also be ok.

That TP article was interesting.. they really like the 'up and over' type legs. Theory being that a rapid change in direction will force the air to condense and fall out of suspension (that's also how a drip leg is supposed to work).

It takes quite a bit of velocity for that to happen... not sure how effective it is in a low CFM shop environment. Also that means more joints to leak and vertical runs that will stand off from the wall (or a header that must be hung away from the wall).

I really haven't dealt with any moisture issues in my simple setup (1 in black pipe header with T's and vertical up nipples). Maybe what I have is enough.

I interpret the up "up and over" take-off pipe to simply allow water to stay in the pipe and eventually flow downwards to the drains and never move towards a take-off.

I think that the "Theory being that a rapid change in direction will force the air to condense and fall out of suspension." is not the reason.

If it's not where it can be easily damaged from impact I would use PVC. Otherwise I would use galvanized iron, not black.

PVC is not rated for compressed gas, and sends flying shards when it fails. Not a good choice, and why OSHA finds it illegal in commercial settings.


http://www.garagejournal.com/forum/showthread.php?t=141899




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Thanks all! Thanks Tim for the TP tools website.... and you live in Upstate NY and realize the temperature ranges. I would prefer to run inside but there are way to many obstacles. The new lines won't be hard line into compressor. I'll use a rubber line from compressor to exterior black pipe about 10'. There won't be a lot of usage you know tires, impacts, ratchets and driveway repairs. I'll taper the run and use a a lower ball valve to drain. Other thoughts??? Thanks all
Dan

Dan,

I have had that design of air-plumbing in my unheated garage for about 10 years. In November, before the deep-freeze sets in, I drain all drops in the piping and I drain the compressor.

It gets humid here in the summer, but it is relatively dry air from Nov to April.

The only thing I failed to put in my air-plumbing is the pressure release valve in the vertical line near the compressor.

By the way, I used a high-pressure-rated flexible metal line/hose (200psi rated - for water heater) between the compressor and the black-pipe.

PVC breaks, black pipe as well as galvanized pipe rusts from the inside. Our shop is piped with 1" rigid copper with compression fittings. I run everything through a 50 CFM refrigerated air dryer. I use 1" hydraulic hoses for the dryer. I had a pretty neat installation until the dryer I had for about 20 years quit. I bought a different brand that had the outlets placed differently.

https://plus.google.com/10819770718...7945047986&oid=108197707187186692269

This piping is in an unheated shed and we do get temperatures in the teens, single digits and occasionally down to 0°. We need air, and can't afford freeze ups.

I've gone away from any type of rigid pipe and have started using DOT air brake lines. They operate in a 150 psi blow off system with a 130 psi working pressure. And bounce down the road the whole time. Actually, 120 psi working, 130 psi for wedge brakes. And the lines turn corners much better than rigid stuff.

When we did our plumbing, 1" Synflex was special order and much more expensive than rigid copper. And 50 CFM requires 1" And Synflex isn't forever either. That is why I buy it by the roll for replacement on our trucks. It is especially vulnerable around bends. However, If I just used only one or so air tool at a time, I would consider this 1/2" hose.
http://www.ryderfleetproducts.com/tectran-1928-05/airbrake-tubing-1-2-red-per-ft-ttm-p-ttm-192805

75¢ a foot is about as good a price as I have found.

Why don't you paint the black iron? The portion of my black iron propane line that is outside rusted in less than a year. It's now painted with some leftover POR-15.

I've used galvanized for air lines in the last 4 places I lived. Removed and re-used most of it each time I moved. Still looked OK on the inside after the last move. Cheaper to buy 21 ft lengths at a plumbing supply.

Many of the chemical plants I've been in use galvanized for instrument air lines and never have problems with flaking.

A rapid change in direction is how most water separators work.

Water does not know it should 'stay in' a horizontal run... water is carried by the air wherever it takes it.

I have 3/4" black pipe in my shop at the farm. Just installed 3/4" pipe in the shop at the house. The cost versus alternatives just worked for me. First setup in the farm shop was PVC. Had a PVC fitting detonate one day. like a shotgun going off. Immediately replaced with pipe. Drip legs at every outlet, drain regularly. Ran my CNC plasma cutter in high Central Texas heat and humidity. dumped a lot of water, but pipe is fine and never had any issues with excessive water. Painting, drain everything, purge water separators, add a good water filter at the outlet your air will come from, and a disposable filter at the gun. knock on wood, no water issues, but I don't paint everyday for a living.

My fear with some of the specialty air supply companies and lines, finding fitting for expansion, changes, or repairs may be tough if the company goes out of business. Its why I now have a mostly defunct CNC plasma table. Availability of repair parts is now an important part of my consideration when buying stuff. Stuff will break, gotta get parts.

True about water separators, but they can't get the water vapor out of the air. The water vapor does travel with the air, but a separator only takes out the part that's condensing or on the verge of condensing when it hits the surface of the separator. If you were to run compressed air line from an indoor heated space to outside (colder), the water vapor would condense out of the air in the outside run and collect on the inside surface of the pipe. And once it's liquid water, gravity takes over and it runs to low spots, whether in the bottom of a horizontal run or down into drip legs. Like someone else already said, separators need relatively high velocity (rapid change in direction to use your words) to work well and a typical air system velocity is low.

What I would do on a run outside and back in is to pitch the pipe down in the direction that the air is traveling and put a drip leg with drain valve with a good size rise in the main just after it gets back inside. That way any condensed water vapor would run to the low spot and be drainable.

I used a vertical 24" section of 6" Schedule 40 black pipe with caps welded onto both ends as a water trap, welded bungs into the top of the pipe for inlets and outlets, and a bung for a ball valve in the bottom cap for drainage. At the end of the workday, just open the ball valve and drain the condensation. Place the water trap as far away from the compressor as is practical to allow the air to cool down and condense the moisture. Tilt the pipe from the compressor to the water trap downhill slightly.
Jerry