Compressor - what's the need for larger tanks?

[snowphun]

I'm looking to replace my *noisy*, leaky, old Crafstman 20 gallon oil less compressor. Unlike many people on here I don't think I have a need for a large compressor: it will actuate the locks on my Bend Pak and power an impact gun for occasional auto repair. Neither of these seem like situations where I need a lot of CFM. So the Makita MAC2400 ( http://www.amazon.com/gp/product/B0001Q2VPK/?tag=atomicindus08-20 ) or larger MAC5200 is very appealing to me: quiet, pretty small and 4.2 CFM @ 90 PSI seems pretty solid. Most impact guns are in the 4-5 CFM range, but I'll be using them for a few seconds at a time, not continuosly.

So what is the need for a larger tank? If the Makita can sustain 4.2 CFM (or 6.5 CFM with the MAC5200) and my tools are under that, do I have any need for a large tank? I'm guessing a smaller tank compessor will cylce on more often and longer? Anything else to consider?

Cliff notes: I want a quiet, relatively small, 120v compressor. I can get the Makita for $360 or less.

`

 

[Frank The Plumber]

System buffer.

 

[oldgoat]

With a small tank your compressor will be turning on all the time. With a tank it gives you a reserve. The Makita sounds like a good compressor, but I'd keep the old tank and pipe into it first and then run off the tank. Oil less compressors are always by my experience quite noisy. You might be surprised at how much the impact will use if you are using it much at all.

 

[dirttracker18]

Keep your old Craftsman, dismantle the pump and motor and remove them. Run a line from your new compressor to the craftsman and now you have extra air storage. I still have my old craftsman compressor tank for just such a purpose. I have rarely needed it but if one is painting it could be helpful. I also use it an air tank to take to the races. I left the wheels on it so I can fill it and roll it out to the trailer. If I happen to run out there lots of guys have a compressor at the track and I can just refill it.

 

[LWW]

DirtTracker does what I do. I started with a 110v 30gal Craftsman oilless compressor that was/is noisy as hell. When I upgraded to a 60gal IR 230v oiled compressor I put a T and a valve in the air supply line and plumbed the Craftsman into the main system with the new IR compressor.

Now I use the old Craftsman when I go to the track since it will plug into anyone's 110v service and when I get home I have 90+gal capacity. I also have two 15gal "auxiliary" tanks plumbed in but that's only because I have psychological problems...

If you want quiet, you HAVE to go with an oiled compressor. Even then I would add an intake muffler to quiet it up even more.

In your case, with the old tank I would look for the smallest oiled compressor. That will give you what you're looking for but also give you enough capacity in the event you need more air. The old tank is already paid for so there's no reason to throw it out. If it's in the way, plumb it outside and build a little "shed" over it. It only needs to be connected to the air supply by one end.

Good luck!

 

[donhd04]

ive got a small 30 gal craftsman and it wont' bust any lugnut or even a brake caliper bolt loose. but i can use my dads 60 tractor supply and zip em right off all day long. whats the issue with the smaller tanks?

 

[6530]

ive got a small 30 gal craftsman and it wont' bust any lugnut or even a brake caliper bolt loose. but i can use my dads 60 tractor supply and zip em right off all day long. whats the issue with the smaller tanks?

What size regulator does the Sears compressor have? What size air lines are you using? Either/both of these will have a much more significant impact on the air volume than tank size.

 

[MattT]

So what is the need for a larger tank? If the Makita can sustain 4.2 CFM (or 6.5 CFM with the MAC5200) and my tools are under that, do I have any need for a large tank? I'm guessing a smaller tank compessor will cylce on more often and longer? Anything else to consider?

I've got an IR framing compressor about the same as the Makita. It won't run an impact at full power by itself. Average impact cfm might be around 4cfm but running they use a lot more air so they **** down the little tank and the compressor can't keep up.

What I've done is hook mine up to a scrounged 20 gallon tank and it works well with my impact now. So yes you can get by with the smaller compressor if you hook it up to your old compressors tank.

 

[MattT]

ive got a small 30 gal craftsman and it wont' bust any lugnut or even a brake caliper bolt loose. but i can use my dads 60 tractor supply and zip em right off all day long. whats the issue with the smaller tanks?

What size regulator does the Sears compressor have? What size air lines are you using? Either/both of these will have a much more significant impact on the air volume than tank size.

Yeah with a 30 gallon tank your problem is plumbing unless your pressure switch is cutting off too low.

 

[wrnch]

Can one of you guys, that have converted your old compressor into an extended tank, post some photos of your setup? Sounds interesting.

 

[LWW]

ive got a small 30 gal craftsman and it wont' bust any lugnut or even a brake caliper bolt loose. but i can use my dads 60 tractor supply and zip em right off all day long. whats the issue with the smaller tanks?

Sounds like your line pressure regulator is turned or stuck in the "low pressure" setting if it's the same 30gal Craftsman I have or you're running very restrictive 1/4" line or connectors. That will reduce the amount of air your tool has to work with and will limit it's capabilities. 3/8" hose and fittings will make a HUGE difference and will make a small setup work like a big setup until your tank gets low and the little compressor has to kick-in and try to catch-up.

Mine is the old model with the "claimed" 6hp oil-less compressor. After they were sued Craftsman had to "re-badge" them to the current REAL running 1.6hp. Even so, it still runs my Craftsman impact well enough to pull off a wheel at a time with little effort. Before I added my 60gal IR compressor the Craftsman worked fine with the extra tanks I have for capacity.

 

[Joe69]

Can one of you guys, that have converted your old compressor into an extended tank, post some photos of your setup? Sounds interesting.

I plumbed a 25 gallon tank onto my 8 gallon Emglo. It will now run a 3/4 impact, where it wouldn't before. Here's a pic. It's not a very good one, but it's the only one I have right now. I ran the discharge line from the compressor tank to the red 25 gal tank. You can see the line coming out of the blue tank, just behing the fire extinguisher, and going to the top of the red tank. You'd be amazed at how dry the air is after going thru 3 separate tanks. The first tank catches most of the moisture, and the 2nd catches basically everything that's left.

Joe

 

[snowphun]

What I've done is hook mine up to a scrounged 20 gallon tank and it works well with my impact now. So yes you can get by with the smaller compressor if you hook it up to your old compressors tank.

This is a tempting idea, I could put a valve on the old tank and only use it when necessary.

 

[snowphun]

For guys that put their compressor outside or away from the garage, how do you turn it on remotely? I have power outside my house and could easily run air lines but I don't want to have to go back and forth from the garage to power it on/off, and I don't want to leave it on all the time.

 

[LWW]

For guys that put their compressor outside or away from the garage, how do you turn it on remotely? I have power outside my house and could easily run air lines but I don't want to have to go back and forth from the garage to power it on/off, and I don't want to leave it on all the time.

Either install a 20/30amp switch and run a new "switched" circuit out to your compressor or simply put a switch on your existing circuit inside the garage. It really depends on where your circuit runs and where your breaker panel is located.

Mine is on a dedicated circuit so I just leave it on all the time. If I don't want it to run, I turn off the main air line valve and if there's no leaks the compressor won't run. I have an automatic water drain valve on my tank that is activated every time the compressor starts or stops so I don't have to worry about condensation buildup in my tank. For $15 from HarborFreight it's worth every penny:

http://www.harborfreight.com/automatic-compressor-drain-kit-46960.html

I have one on my main 60gal IR and one on my "auxiliary" 30gal Craftsman. between that and the inline water separator, it stays pretty dry in my system.

 

[snowphun]

Either install a 20/30amp switch and run a new "switched" circuit out to your compressor or simply put a switch on your existing circuit inside the garage. It really depends on where your circuit runs and where your breaker panel is located.

Mine is on a dedicated circuit so I just leave it on all the time. If I don't want it to run, I turn off the main air line valve and if there's no leaks the compressor won't run.

A dedicated circuit isn't really an option, though I will be putting on one that does little else. This may be more of a PITA than dealing with the noise of the unit being in the garage.

 

[snowphun]

So if I step up my size a bit, I think a 30 gallon twin cylinder unit that runs on 120v would work. Anyone have experience with the Lowes Kobalt 30-Gallon Cast Iron Oil Lubricated Air Compressor ( http://www.lowes.com/pd_221495-1498..._4294795218_4294937087_?Ns=p_product_price|1# ) or the Home Depot Husky 2.0 Running HP 30 Gallon Vertical Compressor ( http://www.homedepot.com/webapp/wcs...talogId=10053&productId=100063473&R=100063473 ). I like the specs on the HD unit and it is cheaper. If I occasionally need more air I can always rig up another tank.

 

[donhd04]

Sounds like your line pressure regulator is turned or stuck in the "low pressure" setting if it's the same 30gal Craftsman I have or you're running very restrictive 1/4" line or connectors. That will reduce the amount of air your tool has to work with and will limit it's capabilities. 3/8" hose and fittings will make a HUGE difference and will make a small setup work like a big setup until your tank gets low and the little compressor has to kick-in and try to catch-up.

Mine is the old model with the "claimed" 6hp oil-less compressor. After they were sued Craftsman had to "re-badge" them to the current REAL running 1.6hp. Even so, it still runs my Craftsman impact well enough to pull off a wheel at a time with little effort. Before I added my 60gal IR compressor the Craftsman worked fine with the extra tanks I have for capacity.

Ive got 3/8 line but it still doesn't do the trick. I also have the 1.6 hp model and have the pressure turned up as far as it will go. any suggestions?

 

[donhd04]

Ive got 3/8 line but it still doesn't do the trick. I also have the 1.6 hp model and have the pressure turned up as far as it will go. any suggestions?

anyone have an answer for this?

 

[MattT]

Ive got 3/8 line but it still doesn't do the trick. I also have the 1.6 hp model and have the pressure turned up as far as it will go. any suggestions?

Try replacing the regulator with a quality, correctly sized, unit first. If that doesn't get it you'll have to keep removing fittings and couplings until you find the restriction.

 

[donhd04]

Try replacing the regulator with a quality, correctly sized, unit first. If that doesn't get it you'll have to keep removing fittings and couplings until you find the restriction.

i'll try taking it apart tonite.

thanks

 

[snorky18]

To the OP, the tank is of secondary importance, your compressor pump itself is most important component.

Think of a big air compressor tank as being similar to having a car with a really big gas tank for long road trips. It’s that much less often you have to stop and fill up, but ultimately if you’re not putting enough gas in the tank to sustain how much you are using, you will run out of gas. Same with air.

 

[SteveU]

Another thing that comes to mind is in case of a power outage you can still use a lot of air if you have a 80 gal tank where if you have a small tank, not so much

 

[reinhardt]

dumb question steve.... why do u need compressed air when the power is out? pneumatic lights? (couldn't help myself)

ben

 

[Indy78]

So if I step up my size a bit, I think a 30 gallon twin cylinder unit that runs on 120v would work. Anyone have experience with the Lowes Kobalt 30-Gallon Cast Iron Oil Lubricated Air Compressor ( http://www.lowes.com/pd_221495-1498..._4294795218_4294937087_?Ns=p_product_price|1# ) or the Home Depot Husky 2.0 Running HP 30 Gallon Vertical Compressor ( http://www.homedepot.com/webapp/wcs...talogId=10053&productId=100063473&R=100063473 ). I like the specs on the HD unit and it is cheaper. If I occasionally need more air I can always rig up another tank.

For a little more you can get a Husky 60 gallon 10.2 scfm at 90psi from homedepot for $438. But it is a 240v.

 

[milner351]

I'm on the opposite end - I have a IR 7.5HP 80 gal that I hooked an additional 60 gal tank to for added capacity - using a sand blasting cabinet takes a lot of air!

I ran a hydraulic hose of the same diameter as the IR tank outlet, off an iron T to the 60 gal tank - the hose isolates the vibration and allows some flex between tanks.

The separate tank will help - and the idea to make it an easily mobile air tank is a great one!

 

[Greatbear]

Another benefit to having a large tank is you lessen "short cycling" of the pump. The pump stays off longer as the reserve is used, then runs longer to replenish. Constantly short-cycling a compressor tends to wear on the switchgear and motor starting devices, and allows moisture to accumulate in the heads and cylinders of the pump, causing rust. When the pump runs longer, more heat is built up and helps drive moisture from the pump.

 

[nissan_crawler]

Honestly, it all depends on the compressor setup.

A larger tank will get you longer before the pump kicks in. However, if you're continuously using air, as soon as the pump kicks in for the first time, tank size just became mostly irrelevant (unless you're running an insanely high cfm pump that can fill the tank in no time).

If your needs are in short bursts, a bigger tank/smaller pump will get you by. If you have more continuous needs, you better get a good pump.

I have a space limitation, so I have a 30 gallon compressor (that I need to finish building one of these days), with an 18 cfm pump and 5 (true) hp motor. Small tank, big pump/motor to keep up.

Now, you have the short cycling issue (constant starting and stopping) to deal with, when you have a setup like that. To combat that, I'm running a dual setup with a pressure switch, and head unloaders. For simple things like filling tires, it will run off the pressure switch. For long use items, open a valve, and it runs off the head unloaders, which are set 10 p.s.i. under the pressure switch. The head unloaders let the pump and motor run continuously without building pressure. This keeps them cool, and eliminates the large power draw at startup.

Next, you have less tank surface area, so it's going to be hotter, and it's going to retain more moisture. So, I have a cooler made from baseboard heat tubing, and a water tower to dry the area before it hits the tank.

There are many ways to skin a cat, some just cost more than others.

 

[Charles (in GA)]

ive got a small 30 gal craftsman and it wont' bust any lugnut or even a brake caliper bolt loose. but i can use my dads 60 tractor supply and zip em right off all day long. whats the issue with the smaller tanks?

Way too many variables here. A 30 gal compressor should work fine if you are getting the pressure and FLOW to the end of the hose. Are you using the exact same impact wrench? different one?

I used a 12 gal/1 hp 1970's Craftsman for years with no problems at all (still have the compressor).

Charles

 

[Charles (in GA)]

dumb question steve.... why do u need compressed air when the power is out? pneumatic lights? (couldn't help myself)

ben

Flat tire?

 

[RBailey]

dumb question steve.... why do u need compressed air when the power is out? pneumatic lights? (couldn't help myself)

ben

Maybe

http://www.wolf-safety.co.uk/airlamps/airturbo/


But they are very air hungry and scream like a b1tch when you used them.
Wet / damp air also plays havoc with them.

We use them when working in the tanks on the oil / chemical tankers.

Cheers,
Richard B.

 

[snowphun]

For a little more you can get a Husky 60 gallon 10.2 scfm at 90psi from homedepot for $438. But it is a 240v.

Yeah, those 60 gallon units certainly seem like a better deal, but they are enormous and super heavy. Even the 30 gallon unit is big and I'd much prefer to put it somewhere besides my garage. I could build a shelter in my backyard for it (I already have power out there) but I have no easy way of switching it on/off and I'm not going to use it enough where I will want to leave it on all the time. I've gotten by well for years with my 20 gallon Craftsman, it's just noisy as can be and a bit tired.

 

[Greatbear]

My 80gal Dayton compressor has a continuous-run unloader setup that I use when doing lots of media blasting. I've been considering a new compressor lately (it's 22 years old) but finding one equipped with an unloader is tough. Then again, the old beast is still chugging along like the day I bought it, so there is no hurry.

 

[southpier]

are you only using the air for running tools? if you ever need to blow out water lines, you'll need some volume, too. just high pressure (without backup volume) can blow a "hole" through water and consequently not evacuate the line.

 

[trbomax]

dumb question steve.... why do u need compressed air when the power is out? pneumatic lights? (couldn't help myself)

ben

air starter on the genset

 

[SteveU]

dumb question steve.... why do u need compressed air when the power is out? pneumatic lights? (couldn't help myself)

ben

Flat tire, or blowing out the carburetor for the generator since it hasn't been run in a few years come to mind. I prefer not to run out of anything & dislike having to wait for the compressor to pump up so I leave it on all the time so it is ready to go at a moments notice.