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Scene Shop Air Compressors?

Discussion in 'Scenery, Props, and Rigging' started by gafftaper, Jul 22, 2007.

  1. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    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!
     
  2. Footer

    Footer Senior Team Senior Team Premium Member

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    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).
     
  3. Van

    Van CBMod CB Mods Premium Member

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    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.
     
  4. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    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?
     
  5. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    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?
     
  6. Charc

    Charc Well-Known Member

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    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.)
     
  7. jwl868

    jwl868 Active Member

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    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
     
  8. jwl868

    jwl868 Active Member

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    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
     
  9. Van

    Van CBMod CB Mods Premium Member

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    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.
     
  10. jwl868

    jwl868 Active Member

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    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
     
  11. Footer

    Footer Senior Team Senior Team Premium Member

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    I have plumbed with both PVC and Steel, the PVC is obviously faster but does not hold up as well. I have not done it with ABS, though if I ever do it again, thats what I will prob go with. Odds are if you are hooking up a portable compressor you will not be running more then 2 or 3 drops, something you can easily do by yourself. If your going to run 20 drops with hose coilers and all that stuff, a contractor would be the way to go. You can do this, easily.
     
  12. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    I found a website that has complete kits for doing your own plumbing. You supply the black pipe to run between stations and it has everything else... including a moisture removal system. Looks like I can do the whole thing for about $300.

    On the other hand I'm considering how much I'm going to be using it and thinking about going portable instead and not worrying about the plumbing work. This guy from Porter Cable looks pretty sweet. Price on line is currently $378 which seems like a good deal for what you get. Buy 50 feet of hose, roll it where I want and forget plumbing.
     
  13. Van

    Van CBMod CB Mods Premium Member

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    one thing to keep in mind it the supply rate, listed as SCFM < sustained cubic feet per minute> The rating that you need is determined by the tools you'll be operating. Nailers, staplers, very little scfm needed just pressure. Cup guns, socket drivers, sanders, grinders and cutting tools can suck up a lot of air causing the compressor to have to run a lot.
    "Ok" , you say, I'm not paying the electrical bill. The other thing to consider is, for example, the unit you linked to has a decibel rating of 84 DBs. Imagine that thing running for 45 minutes straight, while you're trying to fill out a cut list, your pulling from an 1/8 scale elevation. :mrgreen:

    'Course maybe you're lucky and can mount it in another room. Oops I forgot, that's a portable, it's going to be right next to you. Oh, well it is as long as you've got plenty of 10/3 extension cord, or electrical drops every few feet. I've founf that having a pancake to cart around, take out on set, etc. is extremely useful, but a big strong, quiet < realatively speaking> central compressor is essential.

    Oh did I mention, Drain your tank ! Exploding compressor resivoirs are nasty things.
     
  14. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    Yeah it's 5.1 SCFM at 90 psi... which is plenty for all the wood working tools but a little under powered for most sprayers and impact wrenches.

    On the other hand the 175 psi is cool, it cuts in when you drop below 145, so it should be able to maintain a much higher pressure than the typical 150 psi 25 gallon models.

    I store my little pancake compressor with the relief valve open. Hows that for drain all the time?

    As for the noise... hey we'll all have our hearing protection on anyway because I've got to have pretty strict safety rules so what's an extra 82 db? Plus small theater, small college... I imagine most of the time I'll be the one running the tools or closely looking over the shoulder of the kid I'm training.
     
  15. ship

    ship Senior Team Emeritus Premium Member

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    Yep amongst issues, Van I vote for. Work next to the hoist department where as opposed to my various grinders they have air die grinders and use them with great effort for long periods...

    Constant noise or how one does stuff battles asside, it’s tank size, compressor size and type, tube size and line volume available. This much all info for starts in the Backstage Handbook.

    Volume of hose if a long run and high pressure in rapid or rapid in large volume use is just as much a hose issue as volume issue.

    Tank/storage and compressor is on thing, tubing to use area and hose to tool another after this. Not as much noise but use of tool or given that pancake tank, when does it blow it’s top by way of overheating? Used to have one pancake tank that did blow it’s top every 15 minutes. This as opposed to my current system with added in-line storage tank that don’t. This given hoses properly sized and all around what’s needed. Design of the system, more involved than the home owner can do. Hire someone that has studied the concepts.

    Noise... locate the compessor off stage.
     
  16. jwl868

    jwl868 Active Member

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    Just an aside, SCFM stands for "standard cubic feet per minute". For compressed air, the standard conditions are 14.7 psia (pounds per square inch absolute), 68 degrees F, and 36% relative humidity.

    Joe
     
  17. Van

    Van CBMod CB Mods Premium Member

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    Yeah what Jwl said.


    Really I thought it was sustained, as in sustained delivery. Oh well, Live and Learn. I'm big enough to admit when I'm not quite right.



    < notice I didn't say wrong . I'm a TD I can't be wrong. :twisted:>
     
  18. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    Hmm... there is such a price difference between a large portable like I listed above and 60 gal 5HP with a plumbed system. It's really hard to justify that much cash so you don't have to worry as much about hearing protection and don't have to coil as much hose. Yeah there will come a time I would like a tool that requires a higher SCFM... but it's the other 99% of the time where I'm just using one stapler that it makes it really hard to justify spending that much.

    I'm all for spending the money on the better product so you don't regret it later. However, it's one thing to say I'm buying a Delta Table saw instead of a Craftsman because it's more durable and another to upgrade to a product who's capabilities you won't need most of the time.
     
  19. Van

    Van CBMod CB Mods Premium Member

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    I think that's probably the right way to go. I've mostly been playing Devils advocate. You can skimp < a bit> on the compressor, as your department grows, you can always upgrade. A Uni Saw is truly the best way to go, however. A Cheap whimpy tables saw will bog you down in your production capabilities faster than anything. Adding a Beismeyer < sp> fence is also well worth the price. Are you going to be making cabinets ? No, but a good fence and table saw will allow you to reduce the necessity of constantly re-adjusting / trueing the fence. A very wide table and cut-off table will also re-duce the incidents of injury do to improper tools use. My table saw has a 5 foot wide table on it, the cut off table is 5' wide by 9' long, slicing up whole sheets of 3/4 ply can be a one man job < rip, or crosscut> .
     
  20. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    Totally agree on the table saw. I haven't put the whole package together yet for pricing but a Beismeyer fence, a wide extension off to the right, and a good runoff table are at the top of my list. I've also got my eye on this cool little craftsman product. $170... looks like a great way to make ripping 3/4 easy.
     

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