Large Scale Central

Basic Air Tools for G Scale Railroad Projects

I cannot strongly enough advise AGAINST using PVC as an air line. Air under compression is much more dangerous than water under pressure. Please don’t do it.

I agree with Bob and McMaster-Carr states in their catalog to never use PVC pipe for compressed air or gas as well.

Harbor Freight sells the 50 foot rubber air line (hose). That’s what I used. Its designed for that job, and with the air fittings, you can hook 2 together for more length. But the further you go, the more resistance you may have, reducing the available CFMs.

I’m with Bob and Gary, don’t do it! Suggested reading -

http://www.hoseandfittingsetc.com/our-blog/bid/94802/what-type-of-pipe-should-i-use-for-my-air-compressor

http://forum.woodenboat.com/showthread.php?104099-CVPC-or-PVC-Air-line

It will probably work until it doesn’t. Just hope no one is around when it fails!!! (http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-surprised.gif)

I agree with the previous comments above…don’t use PVC for your air line system. For the amount of savings in cost for a small “garage” type shop, it is just not worth it to jeopardize the safety of those who will be in your shop. You won’t be using that much air line in your shop to make a big difference.

I echo the comments to not use PVC for air lines. All air compressors (that you can afford) will provide some form of PULSED air compression. This pulsing is what will weaken and eventually cause a crack and ultimately a break. Even in a water line where there might be an air pocket causing water hammer, the same result can be had.

Depending on depth of pockets, I offer two alternatives. First, use 1/4" galvanized steel pipe and fittings available at any local home improvement center. If you are good at measuring, they can cut and thread your lengths for you for a small fee per cut. A little teflon thread tape and a pipe wrench, some strap hangers and an air chuck and you are in business.

The second system, although I am not familiar with the product name, is a aluminum piping system with press in fittings similar to pneumatic push fittings used in automotive/truck applications. I have no idea of the cost for this system, but would anticipate it to be higher than the galvanized pipe.

Although using a flexible air line is an inexpensive option, the possibility of a cut or an abrasion causing a rupture would cause me to shy away from that course of action.

FWIW

Bob C.

If you cannot use galvanized piping the next best thing would be to use copper pipe with sweated fittings. It is used in the Health Care industry all the time. I have built many hospitals over my career and have had many air lines and oxygen lines installed using copper. BUT do not use PVC.

David Fielding said:

I see a Harbor Freight 3 gallon 1/3 HP compressor for $40 and a variety of nail/staple/pin guns. I see 16, 18, 20 gauge nailers/staplers and 23 gauge pin nailers.

Are the above tools a bad choice? I’m not looking to spend a lot on high end tools I will use infrequently. I’m also looking for information on the set of gauges and type of tools (nailer, stapler, pin) I should consider acquiring.

Thanks in advance.

Trying to say on topic since it upsets some if we do not stay on topic

this post has been edited by:ROOSTER

reason for edit:post count

For those considering PVC you may want to look at something like Rapidair’s MaxLine Semi Flexible Tubing system; it’s even available at Amazon and Home Depot and not too spendy. I have a friend that just told me he had seen one in an acquaintance’s garage and is thinking about it for himself.

" Rooster " said:

David Fielding said:

I see a Harbor Freight 3 gallon 1/3 HP compressor for $40 and a variety of nail/staple/pin guns. I see 16, 18, 20 gauge nailers/staplers and 23 gauge pin nailers.

Are the above tools a bad choice? I’m not looking to spend a lot on high end tools I will use infrequently. I’m also looking for information on the set of gauges and type of tools (nailer, stapler, pin) I should consider acquiring.

Thanks in advance.

Trying to say on topic since it upsets some if we do not stay on topic

And to that I’ll point out that the higher the number the smaller the diameter of the fastener. Also the nails have a head to them and the 23 gauge pin is simply a piece of wire without a head. The pin nailer is great for holding things together until the glue dries or a mechanical fastener (screw, nut/bolt) is set in place, but you can pull your work apart if only pinned as there is nothing to resist it.(http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-cool.gif)

this post has been edited by:ROOSTER

reason for edit:post count

David yes and no. If you cross pin, it holds pretty well.

What I mean is if you drive 2 pins in, both at an angle, and at opposing angles (one to the right the other to the left), then the pins can hold well without glue. Or, while the glue sets.

David Maynard said:

David yes and no. If you cross pin, it holds pretty well.

What I mean is if you drive 2 pins in, both at an angle, and at opposing angles (one to the right the other to the left), then the pins can hold well without glue. Or, while the glue sets.

And the p*ssing wars just don’t stop. If I drive 4 I don’t need any glue (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-cool.gif)

Oh, ah. (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-surprised.gif)Well. I tend to cross nail everything I build. It just makes it much more secure. Of course I am also the idiot that puts some wood glue on the nails before I drive them in, to help lubricate the nail, and to help secure it once its been driven home.

I wasn’t trying to get into any kind of contest or war. I have better things to do with my time. Next on my list is sorting my socks, and then I was going to round up the dust bunnies and arrange them by size.

If using copper pipe, check the rating as Lowes and depot have the lower rating pipes, supply houses have a higher rated copper pipes and obviously cost more. Same for the elbows and tees.

Echoing Dan’s comment above, use Copper rated ‘K’ for air service. This is the heaviest wall thickness, and also therefore the most expensive. It is also them best suited to air line service. Also use a high silver bearing solder for the joints. This type of solder will most likely be found at either a welding supply or your local AC supply house. It will also require a higher heat to melt/wick the solder into the joint. Standard 60/40 plumbing solder is not a strong and will not stand up well. Again, the service is a pulsing pressure when the compressor is running.

Thanks for the warning on PVC. Never even considered it wouldn’t work. I have seen it done but that doesn’t mean it was right. suggestion noted and I will switch to a more appropriate materiel. I am not at all opposed to galvanized. I have access to all the tools at work to cut and thread it to whatever length.

Good call. thanks all.

Echoing what David M said, HF air hose might be a lot cheaper than copper. For example, $50 for a “premium” 1/2" 100’ coil. Copper, at 1/2" nom, 10x 10’ long would be at least twice that (in type “L”).

I don’t know though what the codes might say about “permanently” installing hose for this sort of service.

Lowes sells a garage air kit for around $50. I’m considering it myself.

As a Mechanical Contractor that installs compressor driven air distribution systems in commercial light industrial operations for air tools, pneumatic valves, and similar ilk with typical operating pressures of 150 psi, I’ve been using copper tubing for 35 years at the least.

Type L copper is generally specified for these applications, working pressure for ‘L’ ¾” hard drawn copper tube is 1000 psi (type L plumbing copper pipe), standard copper fittings soldered with 95/5 solder have a working pressure rating of 625 psi @ 150*F. Quality copper fittings are in the 700psi range.

While PVC works and many use it for compressed air it’s definitely is not a good idea… OSHA specifically calls out PVC because of its shortcomings, i.e., with age and heat exposure it becomes brittle, oils and some solvents break it down and UV rays adversely affect it too.

Galvanized pipe systems are all too common but have their shortcomings with regard to plating coming off contaminating the air supply and the rougher finish afforded same.

Black pipe typical of gas piping is often used in favor of galvanized pipe for air supply systems, even with the consideration for rust developing.

Typical compressed air is realized as a heated moisture laden vapor, as the moisture laden vapor travels it cools, condensate derived from the vapor cooling within the distribution system needs to be drained off. A proper air distribution system is designed with a consideration for the condensate to travel in its liquid form to a drain device at the end of the line. All air supply drops or taps should be pulled vertically off a horizontal supply pipe installed with grade or fall; sloping to the end of the supply line if possible.

Michael

Cliff Jennings said:

Echoing what David M said, HF air hose might be a lot cheaper than copper. For example, $50 for a “premium” 1/2" 100’ coil. Copper, at 1/2" nom, 10x 10’ long would be at least twice that (in type “L”).

I don’t know though what the codes might say about “permanently” installing hose for this sort of service.

Cliff, I don’t worry about codes, because my installs aren’t permanent. In a home shop setting, I am not sure codes would apply unless the install is suggested to be permanent. My hose through the attic system only lasted about 10 years or so. My new work area has extension cords running under the floor. The floor, the walls, the power, all of it is of a temporary nature. If/when it comes time to sell the house, all of that will be removed before the first appraisal.