# How many auxillary air tanks?



## joker

I have a DeWalt 4.5 Gallon 200 psi air compressor (5.2 cfm @ 90 PSI)

I currently have 4 pneumatic props and the 4.5 gallons of air isn't enough to run them without having to cycle.

What I'd like to do is put some air storage tanks in line (harbor freight has some 11 gallon tanks for $39) between the compressor and the props to avoid the cycle times and hopefully extend the life of my compressor.

Would putting four or five 11 gallon tanks in line be just as hard on the compressor as having it cycle each time the props are fired?

Should my compressor handle that much storage?


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## DarkShadows

wow, your going to burn up the compressor if you add that many. It's going to be on for so long just to fill up those 60 gallons of air at once. I have a 17 gallon compressor with one 8 gallon reserve.. Im running about 9 pneumatic props and it only cycles about once a half hour. IMO, Upgrade to a bigger compressor or I'd just run one 11 gallon reserve. Set your timers so there not going off every 15 seconds and you'll be fine.


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## DieTodtenReitenSchnell

Joker,
There are several things to consider. First, in your thinking about your compressor, there is a difference between volume and pressure. The biggest reason to have a tank is to provide "close" air to your affect. Tanks used in this manner are called "Accumulators" btw. If you have an effect that uses a lot of air all at once, then having a small line to somewhere far away causes the line to "starve" for want of air. Having an accumulator nearby the effect means that you can deplete the tank before worrying about the line starving. The thing with that is, you really need an effect that pulls down a lot of air at once. If you're blasting people with air with the 99 cent venturi nozzles you can also get at Harbor Freight Tools (blue ones), then you could dump a lot of air, certainly, and an accumulator close by is great for that. But a pneumatic cylinder is only going to move air for the length of the cylinder, which isn't much air, and running a line to it in this case, even multiple, is no big deal.

So back to your compressor. If you have a 1000 gallon tank, your compressor would run and run and run to fill it up. If you used 1000 gallons an hour, your accumulator would be depleted before your compressor would need to run again (in theory). But it ran from the beginning for a long time to fill it up. So whether you fill it up to start with or fill it up on-the-fly doesn't matter in terms of volume and the life of your compressor. Trying to not have your compressor run very often is a different story. Here, the accumlator would eliminate the need for the compressor to run, and actually, you could unplug the compressor until the 1000 gallons is depleted (if you had one). However, again, when it does run, it will run to fill the tank instead of filling the effect. So mostly all your doing is changing the time at which the compressor runs. This is IMHO and I am not positive that every combination would yield that result, but I think so.

Generally I use accumulators as a distribution section. So if I have a cemetery with lots of pneumatics, I put one accumulator tank (I actually have the HFT ones too) where that "group" of effects are, and maybe if I have another "group" far away, I put a different tank there. But mostly this is to avoid running lots of single lines all over the place. I don't say this is the only way to do it, it's just my way for simplicity.

Hope that helps...years later...


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## joker

DarkShadows said:


> wow, your going to burn up the compressor if you add that many...


That's why I'm asking. Wasn't sure if it was better to run the compressor for 2 minutes at a time every 15 minutes or run it for longer periods of time with a longer duration between cycles.



DieTodtenReitenSchnell said:


> Joker,
> There are several things to consider. First, in your thinking about your compressor, there is a difference between volume and pressure. The biggest reason to have a tank is to provide "close" air to your affect. Tanks used in this manner are called "Accumulators" btw. If you have an effect that uses a lot of air all at once, then having a small line to somewhere far away causes the line to "starve" for want of air. Having an accumulator nearby the effect means that you can deplete the tank before worrying about the line starving. The thing with that is, you really need an effect that pulls down a lot of air at once. If you're blasting people with air with the 99 cent venturi nozzles you can also get at Harbor Freight Tools (blue ones), then you could dump a lot of air, certainly, and an accumulator close by is great for that. But a pneumatic cylinder is only going to move air for the length of the cylinder, which isn't much air, and running a line to it in this case, even multiple, is no big deal.
> 
> So back to your compressor. If you have a 1000 gallon tank, your compressor would run and run and run to fill it up. If you used 1000 gallons an hour, your accumulator would be depleted before your compressor would need to run again (in theory). But it ran from the beginning for a long time to fill it up. So whether you fill it up to start with or fill it up on-the-fly doesn't matter in terms of volume and the life of your compressor. Trying to not have your compressor run very often is a different story. Here, the accumlator would eliminate the need for the compressor to run, and actually, you could unplug the compressor until the 1000 gallons is depleted (if you had one). However, again, when it does run, it will run to fill the tank instead of filling the effect. So mostly all your doing is changing the time at which the compressor runs. This is IMHO and I am not positive that every combination would yield that result, but I think so.
> 
> Generally I use accumulators as a distribution section. So if I have a cemetery with lots of pneumatics, I put one accumulator tank (I actually have the HFT ones too) where that "group" of effects are, and maybe if I have another "group" far away, I put a different tank there. But mostly this is to avoid running lots of single lines all over the place. I don't say this is the only way to do it, it's just my way for simplicity.
> 
> Hope that helps...years later...


I really only have one prop that is an air hog, but I am considering adding a ankle tickler prop that will also require quite a bit of air.

Most of my props need volume and not pressure so that's the reason I was looking to add the accumulators. I'm just trying to determine the abilities/cost to make an educated decision about my needs.

Originally I was looking to add an additional 30 gal compressor, but thought if I add a couple or several accumulators thinking I might be able to save a little money and still meet my current and short term future needs.


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## joker

Is this a realistic scenario for a inexpensive compressor and two accumulators?

I'd think that the MIB, jumping Can and Air cannon would require quite a bit of air.









NOTE: I personally would want pressure gauges and pop-off valves on my accumulators.


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## HalloweenRick

I think the setup pictured is fine. I have a 13 gal storage tank that runs my one air prop ( a simple pop-up.) and a 2 gallon air compressor that runs my pneumatic lifter prop. My display is in the front yard, and my air compressor is in the back yard. It cycles approx 5 times on Halloween night, but being in the backyard with my music going no one, not even neighbors has noticed its running. If you get into a situation where you have 10-12 air props, then yeah get a bigger compressor. But you've got at least 25 gallons of air pictured there, and even if it cycled twice that night, can you just run more air hose and move the compressor farther away?


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## DarkLore

For anyone looking for simplified and helpful information on pneumatic air solutions...there's a game section at the bottom of the forum to play while you wait.

jus teasing.


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## joker

HalloweenRick said:


> I think the setup pictured is fine. I have a 13 gal storage tank that runs my one air prop ( a simple pop-up.) and a 2 gallon air compressor that runs my pneumatic lifter prop. My display is in the front yard, and my air compressor is in the back yard. It cycles approx 5 times on Halloween night, but being in the backyard with my music going no one, not even neighbors has noticed its running. If you get into a situation where you have 10-12 air props, then yeah get a bigger compressor. But you've got at least 25 gallons of air pictured there, and even if it cycled twice that night, can you just run more air hose and move the compressor farther away?


How many times a night would you say that your props are activated?


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## joker

DarkLore said:


> For anyone looking for simplified and helpful information on pneumatic air solutions...there's a game section at the bottom of the forum to play while you wait.
> 
> jus teasing.


LOL


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## The Creepster

Ack... just invest in a good air compressor 30 gallons and then you don't have to play the...do I have enough air stored to run my props or is my motor going to burn out halfway through the night....game. I use a 30 gallon compressor and run 2 air cannons, and 7-8 cylinders, which is 4-5 props, with a average of 3-4 activations per minuet. My compressor cycles twice in a 4-5 hour period. Something to think about, plus down the road if you plan on adding more pneumatics then you don't have to start all over again with the unknown


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## joker

The Creepster said:


> Ack... just invest in a good air compressor 30 gallons and then you don't have to play the...do I have enough air stored to run my props or is my motor going to burn out halfway through the night....game. I use a 30 gallon compressor and run 2 air cannons, and 7-8 cylinders, which is 4-5 props, with a average of 3-4 activations per minuet. My compressor cycles twice in a 4-5 hour period. Something to think about, plus down the road if you plan on adding more pneumatics then you don't have to start all over again with the unknown


That was actually my first thought. I was looking to place an order for some prop controllers and ran across some accumulators and that got me to thinking about the contractor grade compressor I bought designed to run 2 nail guns all day long. Just trying to spend my money wisely.


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## The Creepster

joker said:


> That was actually my first thought. I was looking to place an order for some prop controllers and ran across some accumulators and that got me to thinking about the contractor grade compressor I bought designed to run 2 nail guns all day long. Just trying to spend my money wisely.


I hear you....but by the time you get done buying all these accumulator tanks, and hardware to rig it all up, theres half the cost of a compressor....you know your going to down the road end up running more pneumatics. Always get more then you need when buying tools or equipment... in the long run more cost effective.


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## scream1973

Check the duty cycle on your compressor as well .

The duty cycle is how much time the compressor can safely run within a given period of time, expressed as a ratio. For example, a common duty cycle for compressors is 50/50, meaning that the compressor motor can run about half the time it is supplying air to your tools... 50 minutes on and 50 minutes off. During the "on" time, the motor is pressurizing the tank. During the "off" time, your tools are running on the air stored under pressure in the tank. If your tools are draining the pressure off too fast, the compressor engine must run at more than a 50/50 rate which can lead to overheating and significantly shorten compressor life.

I am betting since its a contractor grade it might have at least a 75% duty cycle possibly even up to 100%


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## scream1973

Looking at your actual compressor it appears to be an oil free model so according to dewalt http://support.dewalt.com/cgi-bin/d...p_faqid=4306&p_created=1202307486&p_topview=1 they recommend a 50-75% duty cycle to avoid shortening the life on the unit.. If it was oiled.. then its 100% duty cycle


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## joker

So basically during an hour of use it could run for 30 minutes of that time and be fine?

Lets say it takes 2 minutes to completely fill and cycles every 4 minutes that would give a run time of 2 minutes, off 2 minutes and then cycle again. Is that within a scenario for a 50% duty cycle?

If I run 3 accumulators and it takes 20 minutes to fill, but only cycles once an hour would the 20 minute running time be too much for compressor?

I'm going to go ahead and buy a 2nd compressor anyway as its a good idea to have a back up so if one fails I'm not completely done for the night.

I'm just trying to figure out if someone wanted to build x number of pneumatic props how they determine which compressor to buy and how many accumulators can they run without risking damage to a compressor.


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## scream1973

Yes that would be a 50% duty cycle.
I think if it ran for 20 minutes out of an hour it would be perfectly fine without any issues. I know my compressor is rated for 75% duty cycle and i have had it running for around 45 mins out of an hour without any issues all day long.


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## tobmaster

I also would be concerned with the pressure you stated. Typically reserve tanks have a blow-off valve that will vent at around 125-130psi. You stated your DeWalt will build 200psi. GREAT for that portable roofing nailer (regulated of course) but just make sure you keep your output pressure down or you'll be running just to overcome the blow-off valves.
I started with a porter-cable pancake compressor and two props...moved to a 30-gallon Coleman Black Max and three 5-gallon reserve tanks...and maybe 10 props....Now I am up to a 70-gallon 220vac compressor coupled to hard-pipe leading out two directions of my house into 50-gallons of reserve tanks out in the yard. Sure there are now 25-props some of which are air-hogs (electric chair, spitters, zombie dudes...), and sure the system runs almost non-stop on Fri/Sat nights in October and all day Halloween....

This season at least two more pneumatic props are on the drawing board. I may couple the old 30-gallon machine to a bypass valve and use it for the smaller part of the yard when in high demand to reduce the overall load. Haven't decided exact plan yet.

So...what is my point??? Well, get the biggest, most efficient compressor you can afford up front so you dont buy three of them like me!!!

Oh, and don't stick your head through your 4-bar mechanics...I'm just sayin'


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