Scene Shop Air Compressors?

[gafftaper]

Hey, I'm trying to pick out the air compressor for my shop and I don't know much about them. I've got my little Porter Cable pancake at home which is great for occasional use, but I don't know anything about industrial quality compressors. I know I want an electric and upright but that's about it. So can you help me out:

How large of a tank should I get?

What horsepower?

Which brands do you recommend?

Brands to avoid?

Any other features I should go for or avoid?

What's in your shop?

Thanks!

[Footer]

Really it will be limited by what kinda tools you will be running and how many will be running at the same time. Also, will you be running hard airlines in your shop or do you want something that you can actually move around if need be? If you get a smaller tank, obviously it will cycle more. I would also get something that has at least a 120-150 psi rating and a good attached regulator. If your just running staplers your air use will be pretty smaller, if your running impact wrenches all the time, go a bit bigger. I think we have around a 30 gallon in the shop with a 2hp motor, i know its a craftsman. We run 2-3 things off it at once, usually in pretty constant use. It cycles about every 15 min or so. However it is small enough that we can drag it around anywhere (also nice since our scene shop isnt a permanent shop).

[Van]

If I had my Druthers, I'd have a much larger compressor than I do. I've got a 2.5 HP 25gal "portable" Sears compressor. It's a heavy duty home compressor. It gets the job done but, I can't paint < cup gun> and run nailers very well at the same it.
Porter cable, Campbell Hausefeild < sp?> either is a good choice. I'd like to have an upright 200 gal 3 - 5 HP also seriously look into plumbing your shop with 3/4" gas pipe, and having regulator stations spread around.
A shop I worked at had this setup where they had taken little peices of ply and mounted a regulator and dryer on them. they had the shop plumbed and the pipes came down to disconnects all over the place. Each regulator setup had a short tail to plug it into the disconnects. The Whole system was charged at the compressors full pressure, 180 psi I think, then you could regulate at the area you were working.

[gafftaper]

I'm fairly handy with a pipe... no jokes please... is plumbing the shop something I can safely do myself or does that require special stuff due to the pressure?

[gafftaper]

As far as the questions about use. I don't imagine that there will be many times that more than one person is using a pneumatic tool at the same time. At the same time I want something that can handle an impact wrench and a sprayer which I can't do on my small home one for more than 30 seconds at a time. So I probably want something in the 30+ Gallon with 2+ HP.

If I get a portable I can just roll it out into the theater if I need it instead of trying to run lines all over. On the other hand if I have the shop plumbed and a line that ran over near the roll up door into the theater, it would be easy enough to just run a line into the theater. I guess that means the question of wheels or not depends on if I install a plumbed system or not.

Van do you have any problems with the Craftsman other than it's a little under powered for your needs?

[Charc]

Originally Posted by gafftaper

I'm fairly handy with a pipe... no jokes please... is plumbing the shop something I can safely do myself or does that require special stuff due to the pressure?

Gaff, as you know, I don't know anything, but I'd think given the amount of pressure, it's worth it to have someone install it. It'll (theoretically) be a good durable quality install, perhaps with some sort of warranty or guarantee, and, god forbid, something were to go wrong with it, and someone were injured or killed, you wouldn't be liable. (Can never be too careful in today's age of lawsuits.)

[jwl868]

For compressed air piping systems, use steel pipe. Small diameter (less than 2.5 inches) uses threaded joints. Larger diameter pipe is welded, but I doubt your system is that big.

DO NOT USE PVC FOR COMPRESSED AIR.

If you want to use a polymer product for the piping, use ABS. Many of the major PVC producers make ABS and market it for compressed air systems.

Make sure the valves are rated for the high pressure.

If you are really comfortable working with threaded steel pipe, you could probably do it yourself, but I don't know if such a system falls under the Plumbing Codes. Plus, the pipe support will require some thought and work.

DO NOT USE PVC FOR COMPRESSED AIR.


Joe

[jwl868]

The more I think about it, because yours is an educational installation (rather than your own personal system or even your own personal place of business), you will be better off having a professional (probably a small mechanical contractor) do the design and installation. While there is the potential liability issue, I would think more about the future: future users, expansion, maintenance, etc. There may be administrative issues – institutional requirements for bidding, capital improvements, budgets, etc. - that may affect limit you doing the actual work.

But there is a large labor cost to this. The materials are relatively inexpensive, but the labor will be significant.

Per your original post:
For an off-the-shelf compressor, manufacturers size the tank (aka receiver) based on the compressor output and the motor (such that the motor won’t start – stop – restart in too short of a period of time). There is also the underlying assumption that the total air demand of the purchaser is less than or equal to the compressor output. For a small application, with only one or two tools operating at one time, the tank sizing is not that rigorous. The tool operates at a constant pressure, assuming that there is a dedicated regulator near the tool inlet. The pressure in the receiver operates over a narrow range; a pressure switch activates (and deactivates) the compressor. The compressor output (in cfm) should be greater than or equal to the usage rate required by the tool. Though you could operate a tool with a higher demand than the compressor output for a short period of time until the receiver pressure gets too low (but that may affect tool performance).

Note that motor horsepower is incidental to the compressor selection. The compressor selection is based on the demand of the tool(s) and the pressure required by the tools (plus additional pressure for the pressure switch controls). The compressor’s pressure output and flow rate (plus efficiency of the compressor) will then determine the motor horsepower.

With more than one tool being used, there is a trade-off between compressor size and receiver size (though I suspect that this becomes less important with smaller compressors and small users simply because the equipment options are limited). Technically (for a large shop), one would go through the exercise of estimating the demand of each tool (looking in the owner’s manual) and the time and frequency of operation of each tool, and what tools are operating at the same time. A large compressor with an output equal to the demand of all of the tools at once with a nominally sized receiver (that is, large enough to minimize motor starts) is one choice. An alternative would be a smaller compressor to match the most frequently used tools, but with a larger receiver sized to accumulate and discharge enough air for other tools used for short periods.

But such an analysis for a small system will be overkill. Most likely the two or three tools that would be used at one time will equal the output of one of the smaller off-the-shelf compressors that include a minimally sized receiver that “matches” the compressor and motor. (Future demand and/or wish-list demand also needs to be considered in the compressor sizing.)

[After I drafted this I realized I was reiterating a lot of what Footer and Van said…]

Joe

[Van]

The Other thing to add is this, If purchasing your compressor from Home Depot, or Sears, BE SURE TO CHECK THE WARRANTY.
I bought a pancake compressor from Home Depot a year and a half ago. Lifetime Warranty, it said. On Everything. Well guess what. When I took it to Portland compressor, the authorized repair facility, 6 months after I bought it, they told me the warranty would not apply as I was a commercial consumer and that parts and labor warranties only applied to home/ individual consumers. How's that for a kettle of fish?.

Oh and plumb it yourself it's relatively simple to do, all the parts are off the self. There are a ton of DIY books availible, and some even reccomend using PVC, I wouldn't in a facility where it's likely to get smashed by anything, and steel pipe is simple to work with.

And remember to drain your tank, at least once a week, Specially here where it rains all the time. You'd be amazed at the amount of water that builds up in your tank very quickly.

[jwl868]

Originally Posted by Van

and some even reccomend using PVC

But don't use it. If you must use plastic, use the ABS (acrylonitrile-butadiene-styrene). See, for example, Chemtrol's literature:

http://www.nibco.com/cms.do?id=2&pId=1

Joe