# Air compressor for pneumatic switches



## Brandon (Jul 6, 2011)

I'll be installing pneumatic switches next summer and will need an air compressor for those. I can't imagine it will take a big compressor and since it's going inside of my train shed, smaller is better. 

Does anyone know what sort of CFM is really needed and if a 1 gallon compressor would be fine or do you need something like 3, 8 or larger gallon compressors?

I also have some chair rail, crown moldings and other small projects to do this fall and winter so I'm just trying to find out if I could potentially get one compressor for both jobs. I won't ever be using spray guns, sanders or other high CFM air tools, basically just a brad nailer or stable gun and other small carpentry like projects, and filling up car tires at times. I'm guessing 1 gallon might not work for these other jobs, and maybe a 3 gallon might be a better for for switches and these projects. I'm not sure if I need to go to the oil type compressors for my needs though, but this is an area where I have no knowledge. I'm not sure if some compressors from HF or depot would be fine either.

Thanks guys,


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## Brandon (Jul 6, 2011)

Digging through online, I see this is amazons top list of compressors: 

http://www.amazon.com/gp/bestsellers/hi/552660/ref=pd_zg_hrsr_hi_1_3_last 

The ones that stand out to an uneducated person on this topic would be: 1 3 4 6 7 12 14 16/20(same parts?) 
If I had to guess, 3, 4, 6 and 20 would probably be the better choices? 
#4, the Campbell Hausfeld seems to be a good price for a 3 gallon 
#6 is suppose to be very quiet and has a quick charge/recharge. 
#20/#16 seem to be a good small size. 
#3 is 6 gallon and has a higher psi but would not fit in my train shed and would require a portable tank which might become a pain for daily train use and depending on how often I'd have to recharge it during a long day of running trains (24 switches that will be part of my automated railroad, and I figure about 4-20 turnout changes per minute at max)


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## toddalin (Jan 4, 2008)

You say you want small.

As an alternative, how about a small compressor to do your turnouts and run an airbrush to do weathering on your equipment, even if it can't do air tools? In that case you would want an oil-less compressor to avoid contamination of the paint.


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## Homo Habilis (Jul 29, 2011)

For what it's worth, I can't recommend the Porter Cable Pancake. I have one and it's very noisy, vibrates like a mutha and is relatively heavy for its capacity. You might consider getting whatever compressor suits your non-railroad needs and use a portable air tank and fill it as necessary. Assuming no air leaks, a tank full should last quite a while unless you're doing a hunk of switching. These tanks are available at HF for a reasonable cost.

p.s. Started answering OP before I saw your second message. You may consider running an air line/hose from where the compressor normally sits, i.e. garage, workshop, and connect it only when operating the layout. As for issues with oil-less/oiled and painting they sell both oil and air traps to address whichever issue.


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## JackM (Jul 29, 2008)

For the 21 pneumatic track switches in my rail yard, I use one of those "pancake" oil-less compressors from HF. They're usually $59 but frequently on sale for just $39. It's noisy as heck but not a problem because it sits in my basement. I use an old X10 system to turn it on or off from my garage. The 1/8" tubing is small enough to poke thru the basement window screen without letting in any uninvited critters. I can close the window when needed and the hose doesn't seem to mind. I only use my air brush in the "off" season; the pancake is loud, but doesn't run so frequently it drives me nuts (it's a short drive anyway). 

Take a look at the tools you have now, or might buy in the future. They should list the requirements as to CFM, etc. Then check out the specs on the compressors. After that, the larger the tank, the less often you'll hear the pump start up again. My most frequent use of air tools is swapping tires on my cars. That uses peak pressure from my compressor, and there's no bigger pain than having to wait, crouched on the concrete floor with gun in hand, for another pressure build up. For any "serious" use you should probably figure on at least $120 (at HF). 

JackM


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## Gary Armitstead (Jan 2, 2008)

Brandon,

I had an old Craftsman compressor 2HP with a 20 gal. tank for about 30 years. Worked fine for air for my Allen ten-wheeler 1.5" live steamer and the pneumatic nail guns and other tools I used to do wood working in my home. Needed the CFM to run that locomotive. It finally quit a few years ago.

I needed a new compressor for my air tools and I decided on #18 on your list...........the Makita 5200 Big Bore. It only has a 5.2 gal. tank, but this compressor recovers very quickly. Much faster than the old Craftsman. It's a bit pricey, but worth the money. Two outlets is nice for multiple tools. I use all Senco products tools.


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## Brandon (Jul 6, 2011)

A line from the garage would require going up through the attic and about 120' of hose. It's do-able, but might be tough. Running the layout will be 95% of the use for the compressor, 4% filling car tires here and there, and 1% using for some chair rail and crown moulding. The brad nailer & stapler I found requires .9cfm and looking up 16 gauge 2" brad nailers they need about 2cfm. I won't be doing sanding, impact wrenches, or even a nail gun (I'll hire a framer to frame my basement when it's time...). I might do air brushing one day though. 

Apparently those amazon top selling numbers/items move around a bit, or at least the #2 vanished (maybe sold out?) 

Here are the items I'm wondering about, from my first pick to last pick 

http://www.amazon.com/BOSTITCH-CAP1...379623472&sr=1-3&keywords=oil+less+compressor 

http://www.amazon.com/Senco-PC1010-1-Horsepower-1-Gallon-Compressor/dp/B0000AQK78/ref=zg_bs_552660_6 

http://www.amazon.com/Senco-PC0968-...379623472&sr=1-8&keywords=oil+less+compressor 

http://www.amazon.com/PORTER-CABLE-...-Compressor/dp/B00519EUCE/ref=zg_bs_552660_23 

http://www.amazon.com/Campbell-Haus...n-Compressor/dp/B002O15NRS/ref=zg_bs_552660_5 

http://www.amazon.com/PORTER-CABLE-...or-Accessory/dp/B000N5UHK0/ref=zg_bs_552660_2 


The ones I was considering were: (and they have 9-256 reviews of 4 star+) 



Anyone know how much air a pneumatic switch from SVRR or E Z Air use per point change?


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## Cmorais (Mar 11, 2013)

Hi Brandon. 

I use Sunset Valley pneumatic switch actuators on my layout, on the main station areas. 

The air source I use to operate them is a couple of 2 liter polycarbonate soda bottles. I fill them to 4 bar (about 60 psi) in the morning using a simple foot pump (about 30 seconds to fill each bottle) and have air up to the evening. I have 8 pneumatic actuators in the main station area. The four actuators on the second station are in a separate system fed by the second bottle (I think a one liter bottle would do for this yard).

The bottles are connected to the piping by means of steel needles, of the type used to fill soccer balls, which pierce the bottles' caps. The caps plastic is quite soft and adjusts very well to the needle, preventing leaks. I usually drill a small 1 mm hole bafore pushing the needle in. If I leave the bottles charged to 4 bar in the evening I typically find the pressure well over 3 bar in the morning.

The water rocket guys charge the bottles at up to 10 bar and say that rupture pressure is about 12 bar, so you would be quite safe using 4 bars. At this pressure the bottles gets very hard and I've never dared to go higher, but it is not really needed. I have never hard a burst bottle.

Try it... it's free and silent...

José Morais
Headmaster of the CFLF


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## placitassteam (Jan 2, 2008)

I can run all day on a 2 gallon tank from Harbor Freight and hardly drop the pressure. I fill it from my big noisy compressor. I don't do a lot of switching. It takes very little air to move the points. Most of the air is used to fill the line as the air is bled off each time the points are released. Therefore a lot of the air usage depends on the length of the air lines.


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## Tenwheeler (Mar 5, 2010)

Brandon, 

I do have 2 of the Porter Cable 6 gal. pancake compressors which work just great. Yes, they are a little noisy if you are standing next to them. One of the compresssors sits near my modeling bench which is used to operate the pin nailer. The second compressor is in the wood shop and provides plenty of volume/pressure to operate the brad and crown nailer. Next spring, I also will be installing some of the Sunset Valley pneumatic switches on the layout and plan to build an enclosure for the compressor. 

Word of advise: no matter which type/size compressor you purchase, BE SURE TO READ THE BREAK IN INSTRUCTIONS. Not following the instructions will ruin the compressor.


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## SRW (Jan 13, 2010)

Just glancing at this thread but you may want to message Doc Watson on the pneumatic switch issue. His switches and air lines have been down for years and work flawlessly when I visit. He uses a small compressed tank to run them that he carries from his shop out to the layout. Jus' sayin' 

For carpentry work I have a Porter Cable pancake compressor that will fire all of my nail guns from framing nailers down to stapler guns. I haven't tried to use it for painting. I have thought of using it to charge a tank with a moisture condenser for painting to avoid pulsing but haven't done that yet.

Scott


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## Greg Elmassian (Jan 3, 2008)

I have 27 pneumatic switches. I have 3 accumulators near each of the 3 groups of solenoids that control the switches. The accumulators are fed from the 1/8" line so I can keep the feed line small, but get full 40 psi. 

I'd thing a 1 gallon compressor would be fine for my layout. 

See my web site: http://elmassian.com/trains/track-aamp-switches/air-operated-switches 

Greg


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## docwatsonva (Jan 2, 2008)

Brandon,

Just to confirm and re-iterate what's been said above I have been using air pistons to contol my switches for at least 15 years. Many of the pistons I use now are that old. I've had minimum failures over that period of time.

I use a Craftsman 2 Hp, 6 gal. compressor for all my hobby and home needs. I use it for air brushing, filling my tank for the switches and brad nailing. It's obviously not big enough for air tools but I don't use them anyway.












To run my air switches all day I use a small 5 gal. protable tank with an additional valve set at 40 lbs. That's all you need to throw your switches.











One other thing I've done with the air pistons is to power my sidings using a small micro switch at the opposite end of the throw. Here's a photo of my setup. These switches are pretty weather proof. Some I've had out years round for over 5 years.










The micro switch is shown on the right.

Doc


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## Greg Elmassian (Jan 3, 2008)

I have a large compressor, way overkill, but I have run my layout several days from a 5 gallon unit filled to 125 psi to start, and I run a 40 psi output likewise. 

Greg


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## Brandon (Jul 6, 2011)

But it sounds like no one knows how many cubic feet or .0000? gallons of air a point takes to switch? If I knew that, I could determine how big of a tank I'd need for a day of running with lots of switching.


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## Brandon (Jul 6, 2011)

For others, who might be interested... It appears a cylinder I could find specs on (clippard for example) has a bore of .15625 and a stroke of .25" I'm going to side on over estimating and going with a 1/4" .25 bore and .6" (this throw was mentioned on a thread here) stroke which gives us a cubic inch volume of .029437 cubic inches. 

A gallon has 231 cubic inches. I have a feeling I'm missing something but this could mean with 1 gallon you could get 7847 switches if you have no loss. 

I have no idea how having a tank at 100psi with a valve reducing it to 35psi affects the number of throws or anything else or if 7847 is not valid due to various other factors. 

If you figure 8 hours of running trains and 12 point changes per minute, that's 5760 changes and I believe the cylinder only loses air for a full back and forth movement, so really you can figure 7847*2 point changes on a 1 gallon tank. One question I have is how much of a tank you can use up before psi drops from 100 to the minimum 35 used for switching. 

Now Greg or someone else jump in and poke holes and correct my inaccuracies.


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## toddalin (Jan 4, 2008)

Lots of flaws in your methodology. 

Ignoring regulators for a moment, how many PSI do the cylinders need to operate properly and how many PSI can they continuously tolerate?

From college chemistry: PV=NRT

Where:

P = Pressure
V = Volume of air tank
N = Mole number of molecules
R = Ideal gas constant
T = temperature

Ambient pressure = 14.7 PSI

Assume V, R, and T are all constant then the pressure is a direct function of the number of molecules (in moles)

If we assume that the air "tank" is "empty," it is not really empty and already has 1 "volume" of air in it, or it would be under vacuum. So if we add another "volume" of air to the tank the pressure doubles and is now 14.7 PSI above the ambient. If the pneumatic cylinders could operate down to 0 PSI, you would have 1 tank "volume" to operate from.

If we pump the tank up to 29.4 PSI it would have 4 volumes in it and you would have 3 volumes that you could draw from before the pressue went down to 0 PSI.

BTW, the measure is 268.8 cu in per gallon for dry volume (rather than 231 cu in per gallon for wet volume).


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## Brandon (Jul 6, 2011)

Cylinders need 35psi to function. I also found another clippard cylinder that was referenced on this site for switches and it actually was a .375" bore and .5" stroke making it have a volume of .055 cubic feet. I started to look up an air constant and other parameters of pv=nrt and decided that since I worked until 8pm tonight, my brain has had enough...


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## SRW (Jan 13, 2010)

Hmmm, how many switches are you considering installing on your layout? 30? 40? Switching them all every few minutes or so? Did I miss that somewhere in the thread. Seems like one person says they can run their switches all day long with a 2 gal. charged tank. Another guy is using 2 liter soda bottles, Doc has about a dozen switches he runs all day long with air to spare from a 5 gallon tank. Greg runs over 2 dozen switches for days with a charged tank. I'm just guessing here but thinking getting anybody's inexpensive little, noisy-ass, pancake compressor, [my porter cable makes me jump out of my socks every time it kicks on if I'm standing near it. My solution was to buy a longer air hose and put the s.o.b. as far away from me as possible. On the up side I scored a great package deal on it a few Christmas's ago from lowe's that had compressor and their very nice brad nailer and stapler for a stupid low price. Works great.], to charge a five gallon tank with regulator it should probably run your switches and I'm guessing a moisture trap in line from the charged tank could be handy someday to run an airbrush. Jus' sayin'

S


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## Greg Elmassian (Jan 3, 2008)

run the air through a dryer/water trap before you get to the switch actuators, you don't want water sitting in the lines. 

yeah, get a 5 gallon tank, charge to 125 psi, will last a long time. 

I have a big compressor, and it's over 100 feet away, so I have local accumulators, shown on my site, the link I provided on the 23rd. 

Greg


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## SRW (Jan 13, 2010)

Posted By Greg Elmassian on 27 Sep 2013 07:36 PM 
run the air through a dryer/water trap before you get to the switch actuators, you don't want water sitting in the lines. 

yeah, get a 5 gallon tank, charge to 125 psi, will last a long time. 

Greg 




There! problem solved. Install 'dem switches and air lines, go to harbor freight and buy youse a 5 gal can that can be charged to 100+ psi, a regulator you can set to 40 psi and moisture trap. Run down to the Shell station on the corner and fill that sucker with their tire pump hose up to the max rating and go home and enjoy you some fine model train switching action. You guys kind of lost me with all that PV=NRT and talking about Moles of air molecules.


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## Greg Elmassian (Jan 3, 2008)

You can get a little 125 psi 12v tire pump to inflate it in the garage every so often, then carry the tank back out to the railroad. 

Greg


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## Greg Elmassian (Jan 3, 2008)

You can get a little 125 psi 12v tire pump to inflate it in the garage every so often, then carry the tank back out to the railroad. 

Greg


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## SRW (Jan 13, 2010)

We've been having a little fun Brandon but I guess what everyone is saying here is that pneumatic switches work reliably and with considerably less engineering than launching the Space Shuttle in to orbit so you probably don't need to overthink this part of your garden layout. I hope you feel confident enough to install these switches in to your layout plans as I have personally seen them work VERY WELL, as have other folks who have commented on this forum, for many, many, years. I personally had more fear of their long term reliability than the initial design but after observing friend's layouts with their airlines buried for many years have seen that they are a very dependable way to operate your switches.


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## Brandon (Jul 6, 2011)

I've decided to go with the Makita MAC700 Big Bore 2.0 HP Air Compressor, 3.4 cfm at 90 psi, 3.8 cfm at 40psi. $200, so more than I wanted to spend for such little use but it's an oil compressor. 

Been looking at oil/water filters. Seems they're all pretty cheap, $5-$15 so I've gone with the TEKTON 4755 Oil/Water Separator, $9 and has 4 star with 120 reviews so it can't be too bad. 

I'm stuck though on picking a regulator. Seems like 34psi is ideal for switches but I've yet to find a regulator that is sold that someone isn't complaining about it being inaccurate. Any recommendations?


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## Brandon (Jul 6, 2011)

Oh, I should note that the items above are in my cart, haven't checked out in case I get pointed in a better direction. The pressure regulator would also be for use on a 5 gallon tank.


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## docwatsonva (Jan 2, 2008)

Brandon,

The pressure regulator I use (shown attached to my air tank in an earlier post) is a cheap one from Harbor Freight. It has worked just fine for over 10 years. The pneumatic switches are very forgiving and don't require an "exact" pressure to operate. I run mine at about 40lbs. (+ or -).

Another thing, I've never used an inline moisture filter either. On a warm day I can sometimes even see a little moisture in the air lines if I look closely. Some pistons have been in use for 15 years.

Don't over analyze. Just do it. You'll be happy with the results.

Doc


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## Totalwrecker (Feb 26, 2009)

Get a 2 stage regulator, one that shows tank pressure and line pressure, that will tell you when to recharge. 
As Doc said, ths part can be cheaper, it's not a precision application. 

Let me be the second to say... Just do it. 

John


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