View Full Version : Air Compressor Use?

Nightmare Grant
06-12-2007, 09:41 PM
I have about 20 animatronics each averaging about 60-70psi. How many air compressors would you use to efficiently power these animatronics? What brand of air compressors do you recommend?

Thanks in advance

06-14-2007, 09:23 PM
Hey, I'll do my best here but I'm afraid that I can't answer your question in a simple way. Again, I'll do my best.

The easy answer to your question is to buy the biggest compressor and tank that you can afford. The hard answer, and the better answer, is more complicated.

The number of props and the pressure that they operate at is not enough information to adequately size a compressor and tank. It really depends on the number of cylinders, their volume, and the frequency of activation for each prop.

You really need to get something that fits your budget, but that pushes the limit. It can never be too big. My guess is that if the props will be triggered fairly often a stand-up style tank like those that you can find in the front of Home Depot would be what you need. 200-250 gallons or so. If they won't be triggered to terribly often, you might get away with a 30-100 gallon tank. Also, keep in mind that there are other factors that can help you here. If the compressor can do more than 100psi (for instance, mine does 125psi) it's a really good deal for you. A 50 gallon tank of 125psi air is equivalent to a 62.5 gallon tank of 100psi air. It's like having a bigger tank and not paying for it. The other thing that most people don't think about is an air accumulator (which is a fdancy name for an extra tank). Often times the problem is not that your compressor is too small, but that you don't have enough storage space and an extra tank can fix that problem.

I realize that this is a lot of talk without too much of an answer, but I warned you of that ahead of time ;)

If you are still perplexed you can message me and I'll see if I can help you more. Good luck.

06-15-2007, 07:21 AM
Remember, it's not the pressure , but rather, the volume the compressor is capable of putting out(CFM's - cubic feet per minute)..the higher the CFM rating, the more volume the compressor can deliver in one duty cycle...air hose diameter, number of runs/splits/bends/length of airlines, etc will clearly affect the volume of air requirements and delivery...adding accumulator tanks will definitely reduce the cylces your compressor will run, and supply "quicker" delivery of air to your props. We've got about 30 props in one haunt, and use an 80 Gallon Craftsman compressor with a 15 gallon reservoir and a 30 gallon reservoir tank...our craftsman supplies air to the reservoirs which power the props. If purchasing one of these "oiless" compressors, and using it without reservoirs, make sure you connect it to a 20 AMP or greater circuit, as the motor will run almost continuously to fill the main tank (not a good idea). Our compressor runs very little to re-fill the main tank with reservoirs in place....if you're running a commercial haunt, you may want to rent a continuous duty industrial compressor..these workhorses run off of diesel, and will deliver large volumes of air without the need of a supply tank...keep in mind, when using one of these compressors, they ARE extremely dangerous, and must be kept outside..very noisy, and require some knowledge of pipe-fitting and hose sizing...sorry to ramble...

06-15-2007, 07:27 AM
A good rule of thumb in sizing a compressor is : take the prop with the largest requirement of pressure (i.e. 75PSI), and approximately double it = 150 PSI...now find a compressor capable of delivering up to 150 PSI...remember to get one with a large CFM output rating too!!!

06-15-2007, 07:54 AM
Anyone have any info on building and/or buying reservoir supply tanks?

Jim Warfield
06-15-2007, 07:56 AM
On the other end of this spectrum , I used a $99.oo dinky compressor, made in Italy with a small pancake tank for quite awhile and it worked just fine.
It could even lift my 205 pounds, quickly, straight up 18 inches for one home-made effect, of course the cylinder was probably 3 inches in diameter so low pressure could be utilyzed.
Most of the time only one air-pressure effect at a time was being used.
I am not disputing the fine advice previously given here, they are right in everything they told you, it's just that sometimes alternate methods can work too.
(Like if all your spending money fits too comfortably in one pocket.)

06-15-2007, 07:59 AM
Doug at Phantasmechanics.com has some documentation on haunting with compressed air...check out his site...www.phantasmechanics.com..

06-15-2007, 08:16 AM
I agree, Jim...it all depends on budget!!

10-30-2007, 02:28 AM
This is from my experience, and I'm sure Craig will back me up on this.

Generally it's all good until you start throwing air cannons into the mix. I'm convinced they are one of the greatest gags out there, but they will eat air like you wouldn't believe. We are running somewhere in the neighborhood of 20 of these little gems right now. Even one air cannon with medium use will kill a small compressor.

Choke points are something to watch as well. Most small compressors, by this is mean something under the industrial diesel big boys, will have 1 or maybe 2 1/4" outlets that you will connect to a 3/8" line. This will only feed so many props. Remember the smallest orifice, even if it is way upstream from your prop is dictating how much air you are pushing. If you have six props that are all triggering at the same time and fighting for air from the same small line it doesn't matter how big your compressor is, or how huge your tank may be, they are going to slow down. Most larger tanks have a 2" outlet that is sized down using a bushing. You can pull that busing and split that 2" outlet down to a 8 1/4" lines. before you will start to run into choke problems.

Water in the airline. This is something we have been fighting all season. We are way down south and humidity is a way of life so we have a particular problem with this one. Water in the lines can cause so many problems it is amazing. The symptoms to look for is props acting stranger and stranger as the night goes on. Sometimes they slow down, sometimes they just stop, or parts of them stop. The simplest solution to this, and it is a drill we are going through now, is to add filters to the lines. Home Depot sells relatively inexpensive filters and if you put them everywhere you split down to a 3/8" line you will save yourself hours and hours of hair pulling.

This comes from years of frustration and the joy of working with some very smart people so take it as you will.


Jim Warfield
10-30-2007, 07:28 AM
My air lines are almost all 1/2-inch galvenised pipe. I install a "T" at numerous low spots with a drip-leg (a nipple) with either a screwed on cap or a valve so I can drain any water out as it accumulates in the pipe system.
The filter I used to have never seemed to do anything. It was clear plastic and there was never a drop of water in it.

10-31-2007, 11:12 AM
I have 4 in my place. I can run them all off one since I only use 40 psi and each has their own holding tank. But we split them up on 2 compressors, and we actually burned one compressor up this year.

To my surprise it wasn't my cheap crappy one ... it was the expensive crappy one :p

11-01-2007, 06:20 AM
We run a number of high usage props, so I'll throw my 2c in on this.

When shopping for a compressor, there are a few things to look for. To start, do yourself a favor and don't buy anything from Sears, Walmart, etc. They only sell oil-less, direct drive compressors. They are extremely loud, very inefficient and will die a quick death with anything but extremely light use. They typically use an aluminum pump and both the pump and the motor typically have extremely low duty cycles.

Look for a good name-brand compressor. Ingersoll Rand, Speedaire, Emglo, Kaeser, Quincy and *some* Campbell Hausfeld are all good names to look for. Specifically, you want to look for an all cast iron pump that is oil lubed and belt driven. Look at the motor, you should be looking for a very high, if not 100% duty cycle. Home Depot's "Husky" line isn't horrible. Two stage pumps will generally last longer, provide higher output pressure and higher CFM than a single stage pump. Keep in mind, this applies to reciprocating compressors. Screw compressors are a whole different world.

Flow isn't everything. 300cfm at 20psi isn't going to do you very good, nor is 1000psi at 1cfm.. At an absolute minimum, look for a compressor that is going to give you 125psi. We have two compressors that will give us 19CFM @ 175psi each.

As far as water in the lines, it's mainly caused from condensation. The cheap way to take care of it is to run a pipe zig-zag from the compressor head, outside, have it zigzag down and then back into the tank. Before it goes back into the tank you will want to put a drop in the line to collect the water, with a valve at the bottom of the drop. This will take care of a large portion of the condensation issue.

The correct solution is a refrigerated air dryer. Expensive yes, but they do their job extremely well.

After the air is cooled down, you will more than likely want to run it into a regulator before it fans out so that you can set your "house" pressure. Our compressors run to 175psi and kick on at 150. Our house pressure is set at 150psi.

Our main lines come off of the house regulator and are 1" schedule 80 PVC. Please don't use SCH40 or ABS. Neither of those can cope with the pressure cycling and will explode eventually. It's a very bad thing (TM). Black iron pipe is perfectly acceptable, though expensive and a pita to work with.

"Accumulator" or "ballast" tanks can help quite a bit. Not only do they increase your overall capacity, but they can also act as "catch bins" for condensation. I place ballast tanks throughout the entire haunt, typically trying to get it as close to a dense area of props as possible. Our haunt air system consists of one 80gallon compressor, 1 60 gallon compressor, both at 175psi. Throughout the haunt we have one 60 gallon and one 80 gallon "main" ballast tanks and a half dozen or so smaller 11 gallon tanks. The smaller 11 gallon tanks are the ones that we T-off from and connect the props to.

Past that, each prop has their own regulator (or 2) and almost all of them at this point have filters and dryer bowls on them. What you'll notice is that the props at furthest away from the compressors will almost never have water issues, it's usually the props closest to the compressor.

As far as the regulator/filter units not working, I can say that they help us out greatly. I'll drain probably a cup of water out of a few of the props that are pretty close to the compressor.


11-01-2007, 07:39 AM
Our main lines come off of the house regulator and are 1" schedule 80 PVC. Please don't use SCH40 or ABS. Neither of those can cope with the pressure cycling and will explode eventually. It's a very bad thing (TM). Black iron pipe is perfectly acceptable, though expensive and a pita to work with.


Just a warning to anyone using anything other than metal pipes to run a main air system, There isn't one pvc pipe manufacturer that dosent say "do not use pvc for compressed air" because no matter what, it will eventually fatigue and explode. At my day job the main air system was all 2" schedule 80, and I almost died when a 2" elbow exploded and large chunks of schrapnel embedded them selves in the plywood wall next to my head. Galvanized and black pipe are really the best and safest ways to go if you have a permanent air system.

Nothing against you Brandon_K, just wanted to let you and everyone else know.

11-01-2007, 10:00 AM
Home Depot's "Husky" line isn't horrible. Two stage pumps will generally last longer, provide higher output pressure and higher CFM than a single stage pump. HTH

Our crappy Craftsman Pro Oilless compressor gave up the ghost mid season this year and I replaced it with an 80 gallon Husky Dual Stage from Home Depot. Seemed like the most bang for the buck and it has performed well. I have one 50 gallon reserve tank in the system, but it is all connected with 1/4" hose....the off season project is to replace the system with 1" black pipe...I am so tempted to use shedule 80 pvc, but I just don't trust it. Especially in an unheated warehouse that has large temperature variations, etc.

11-01-2007, 05:50 PM
We have a 2" mainline with two larger wheel hubs breaking down into multiple 1" lines, the 1" lines then generally get broken down into 3 3/8" lines minus a few exceptions. The wheel hubs have drains on them which after a couple of days give you a nice shower when you drain them. The 3/8" Husky water filters we got from Home Depot tend to fill up multiple times per night and need to be drained.

The size of our compressor and the general humidity of being in New Orleans are both factors leading a a major water battle with our air system. I am sure we are near the extreme in regards to this. If you have a large reservoir tank near, or attached to your compressor that will significantly help with your water problem. Most of it will settle to the bottom of the tank and can be drained accordingly. Our volume is in our lines and air cannons volume tanks, plus our compressor is putting out 380 CFM so who needs a reservoir. We have a number of dips in our system, but late in the night not even those are stopping water from wreaking havoc on our valves. In line water filters are the only thing we have found that can begin to manage our problem. An air dryer would work nicely, but really, who has the money for one of those beasts.


11-04-2007, 11:54 AM
Just a warning to anyone using anything other than metal pipes to run a main air system,

PVC and Compressed air is a long, no win debate. Strong opinions on both sides.

We have to do runs of 200 feet to 1400 feet from our compressors. So we don't have unsightly pipes running everywhere, and are easy to change things around, we use Semi-Truck air-brake line.

These lines are designed for compressed air, are flexable and standard quick-release fittings can be attached to the line.

11-05-2007, 05:44 AM
PVC and Compressed air is a long, no win debate. Strong opinions on both sides.

We have to do runs of 200 feet to 1400 feet from our compressors. So we don't have unsightly pipes running everywhere, and are easy to change things around, we use Semi-Truck air-brake line.

These lines are designed for compressed air, are flexable and standard quick-release fittings can be attached to the line.

Air line is perfectly fit for use as an air system. That's how mine are always ran, especially since we are a temporary attraction. I was just cautioning against PVC pipe. I have also ran air systems out of 3/8" polyurethane and polyethelyne tubing, both of which are also rated for pressure.

Boo Crew Production
11-05-2007, 06:07 AM
I agree with all the great advise above. Another thing that would be very helpful for you is that each one of your props have a reserve tank that has enough capacity to activate your prop twice with a one way valve. With this sett-up you can go with a smaller/cheaper compressor. If you have it in the budget the largest CFM compressor you can get would be great.

The manufacturer I get my prop supply's from also has reserve tanks that resemble cylinders and can be customized to meet your needs.

11-05-2007, 07:36 AM
Harbor freight has these refrigerator dryers for not a lot of money. I have always been tempted to try one out. They go on sale for about $100 off the current price a couple of times a year.



11-05-2007, 03:23 PM

I agree that there isn't any PVC manufactures that I'm aware of that recommend PVC for air use, however I would like to share my thoughts on a few things.

What really does PVC in is "shock". IE, going from 0 to 150psi rapidly. We use 1" SCH80 which is rated at 630psi working pressure. Between our two compressors we have 140 gallons of 175psi air if both are at max. Even if I open both valves at the same, by the time the air goes through the regulator and filters, it still takes a good solid few minutes for the rest of the house air system to "catch up" and equalize. And even then, if both compressors are at max, by the time everything equalizes, the entire system drops to ~50psi due to all of the ballast tanks and air lines. What I'm getting at is, it's close to impossible to "shock" our system, we just don't have the volume at the compressors to do it.

Brett, how long have you been running that Husky? As I said, they aren't bad compressors at all. I have the 30 gallon vertical at home and it's not bad. It runs extremely quiet, has a decent max pressure, runs cool, etc. The only bad thing is that it pulls every bit of 15 amps on 120v, so I can't have anything else on that circuit. For those that go shopping for a Husky, beware, I noticed the other day that they brought in a few of the direct drive oil-less models.

geckofx, 380CFM? I'll assume that it's also pushing upwards of 120+psi? I'm curious, diesel or 3phase? That's a bunch of air!!!

11-05-2007, 07:19 PM
It's a diesel trailer unit that we rent for the month of October. We aim to have the system equalize around 120psi so we are give or take 10 psi or so at any given time. We have some serious high volume draws. We have a 2 section moving floor that can drop an 80 gallon reserve tank from 120 to 60 psi in about 5 seconds, that is with 2 1" incoming airlines. It takes about just as long to refill and triggers every 10seconds or so. We also have 20+ air cannons ranging from 1/2" to 1" valves. They are all regulated to about 80psi or so, well most of them at least, our water cannons run at whatever the current house pressure is. Toss the 20+ props we have, with about a 10second delay between triggers, the occasional air leak, and a busted prop or air cannon venting air and there you have it. We tend to run very hard for an hour to an hour and a half at a time then the system gets to rest. We go through so much volume in that short period of time with everything going off at the same time that simple adding volume tanks wouldn't begin to make up for the usage we have. I'm telling you props are one thing, but once you start adding the really air hungry applications like air cannons and moving floors you enter a whole new dimension of silliness.

The only warning with an air dryer is make damn certain it can handle the capacity you are going to throw at it. If you have an 80CFM compressor running at 120psi, you will need an air dryer that can handle the same or more.

PVC is meant to handle high pressure applications the problems most people run into is what they are using to seal and bond the connections. They have PVC cements and sealants out there that are specially meant for high pressure applications. Talk to a plumber.


11-06-2007, 07:04 AM
100%.....Freddie, could you imagine asking Injun Mike "hey Mike, can you run PVC throughout the whole house so we can pump air through it?"....I can hear him laugh now!! He nearly had a heart attack when asked to install a sprinkler system...

And yes, the air cannons we built definitely added some awesome startle effects, but you're right, they're resource hogs for sure...."More air, anyone?" I'm glad we had that larger CFM compressor...we wouldn't have made it with the other one....

Jim Warfield
11-06-2007, 07:30 AM
There are various grades of pvc pipe, you will recognise the kind meant for high pressure because it will have a rating number printed on it and the side wall is thicker. The average pvc pipe used for most household water systems may not contain 120 pounds of air pressure indefinately, and yes, the better stronger pvc does cost more money.
I use 1/2 inch galvenised steel pipe. Beware the cheaper 1/2 inch galvenised made overseas, some of it is thin-wall and the threads don't hold a seal no matter what you do.