Rapidair which size?

[Robert Engel]

I looked at the product at local Northern Tool the other day. According to the specs, for my application the 1/2” would be adequate, BUT, the lines look very small to me, and then I found out the ID is actually 3/8 (a little misleading IMO).

I use the usual air tools: orbital sander, die grinder, and paint spraying. I do occasionally use air wrenches.

The compressor is 5HP. The run to the wood shop is app 30’. The furthest run is about 45 that will be mostly an air station for painting.

I’m leaning toward going ahead with the 3/4 kit. My mind is telling me with the distance air flow would be degraded.

Thanks.

[Bill Dufour]

What is it? connector, hose or pump?

[Matt Day]

Bigger the better in this case as long as your “5hp” compressor can keep up. I put it in quotes because my Craftsman shop vac is “5hp but is a BS maximum developed, and some compressors do the same.

[Gilbert Vega]

I would go with a 3/4' system especially if you make a complete loop around your shop.
In my case, I bought the 3/4" system (Rapidair Maxline kit). Seeing that was was going to need additional fittings for my 30' x 32' shop I bought 2 kits on sale at Northern Tools. The costs if the additional fittings was almost the same costs of a 2nd complete kit.

I also changed it the shutoff valve on the tank of my 5hp Quincy and added a 1/2 Flexzilla shortly to the regulator.

[Jim Becker]

I think I'd be more comfortable with the 3/4" kit for a shop setup as it will have improved air flow should you decide to use a more demanding tool at some point. There's no down-side to up-sizing outside of a little more initial cost. RapidAir is a nice setup!

[Jim Becker]

What is it? connector, hose or pump?

It's an easily installed system of bendable metallic air "hose" and connection stations that's easy to deploy.

[John Sincerbeaux]

I went with 3/4” Fastpipe. It’s the rigid pipe. I bought everything A-la-cart directly from Rapidair.
Great air setup for any size shop.

[John K Jordan]

Robert,

5 years ago I installed 1/2" RapidAir in my new shop and I'm happy. I use a variety of air tools, small ROSs, nailers and staplers, an healthy impact wrench on farm and automotive tasks, plasma cutter, air up tractor and trailer tires (some to 90 psi), use small air guns in the shop, and a big air gun outside to clean grass clippings off the big mowers and blow out dusty radiators and screens in the diesel equipment. It always delivers all the air I need. I probably have 150' of RapidAir line on three different lines. (I prefer multiple lines each with a separate cut off valve so I can isolate a line if needed.)

I can't imagine the 1/2" being insufficient for a 45' run to a paint sprayer. One thing you might do to test is get a 50' 1/2" and a 50' 3/8" air hose with the fittings you plan to use and test to see if the 1/2" hose causes a problem with your tasks.

When airing up two completely flat bobcat tires recently I probably had the air going through 175' of line and hose, only 50' of which was 3/8". Who knows, the task might have gone quicker with 3/8" all the way but I only rarely have to get air that far from the compressor. My longest run was 400' of 1/2" like to operate a couple of nail guns when putting up a building.

I also use a small sand blaster. My 1/2" lines might be a bottleneck with a larger sand blaster.

How many people might use the air at the same time could make a big difference. I'm the only one using air and around my shop. More than one person at a time would benefit from larger lines (and a loop configuration).

BTW, I use a 5hp 2-stage compressor with a 60 gal tank. It pumps to 160 but I regulate to 90. I installed a bunch of RapidAir outlets in and outside my shop. I have a couple of 50' reels. All of my quick-connect fittings are 1/4". (I don't know anyone who uses larger air fittings except in a large commercial shop.)

JKJ


I looked at the product at local Northern Tool the other day. According to the specs, for my application the 1/2” would be adequate, BUT, the lines look very small to me, and then I found out the ID is actually 3/8 (a little misleading IMO).

I use the usual air tools: orbital sander, die grinder, and paint spraying. I do occasionally use air wrenches.

The compressor is 5HP. The run to the wood shop is app 30’. The furthest run is about 45 that will be mostly an air station for painting.

I’m leaning toward going ahead with the 3/4 kit. My mind is telling me with the distance air flow would be degraded.

Thanks.

[Bill Dufour]

Note that hose, pipe and water tubing are all sized by nominal internal diameter. But air conditioning tubing is sized by it's external diameter. Some tubing including PEX is sized by external diameter. I have no idea how your maker measures it. Probably by outer diameter since that is a bigger number.

[William A Johnston]

I have the 1/2" Rapid Air run throughout my shop with multiple drops and have not had any issues with it. Although I don't have a major pieces of equipment that require a lot of volume of air such as a wide belt sander. I mainly use it for Brad nailers, airing up tires and a blow gun.

If I had to do it all over again I'd opt for the 3/4" lines just for the additional volume so if I ever did get any equipment it would not be an issue.

Like Jim said oversizing will not hurt anything.

Bill

[Robert Engel]

John what I’m doing is very similar to you. Very useful info thanks for taking the time to respond. I have a small farm and do the occasional odd job with air wrenches, etc.

The difference is about $90. I will save the money for more outlets, more piping and a new water separator and go with the 1/2”.

[John K Jordan]

... I will save the money for more outlets, more piping and a new water separator and go with the 1/2”.

Depending on what you do, you might also consider a desiccant dryer after the water separator. I added this one: https://www.amazon.com/gp/product/B002PR8ZXK
It was cheaper six years ago but what wasn't. It uses desiccant cartridges which are expensive so I bought loose indicator desiccant and take the old cartridge apart and reload it, drying the wet decissant in a toaster oven

The dry air is helpful for air tools but really needed for the plasma cutter.

I put the air compressor in a sound-insulated closet with the cyclone and did all the valving and such on the other side of the wall in the main shop. That way I can get to the disconnect, pressure gauge, valves, and regulator and such without going in the closet. The three valves on the right go to three different lines in the shop. I figured if I ever have a problem with one I can isolate it and still use the others. The only picture I have is kind of an oblique shot since the plumbing is in a narrow walkway.

415422

BTW, the pipe should be pliable. I bought two kits and some extra components. The hose in one of the kits was stiffer and I had trouble making a good seal on the connectors. I contacted RapidAir and they sent me a new 100' length of pipe which was much better. You probably won't have that problem but just in case...

JKJ

[Mike Cutler]

Robert

I think you'll be just fine. None of your runs are very long.
A 5HP air compressor is a good sized compressor in a home shop, but in reality is still a very small compressor. A.0625" orifice opening is enough to overcome your compressor. You should be fine with a .375" cross section of hose. If you use the loop concept you'll minimize any pressure drops.
That Rapid Air system looks pretty nice.I've checked it out a few times, but just never pulled the trigger

[Darcy Warner]

I have 3" main air line in mine.
200 gallon tank, 15hp and about 500 feet of main line gives me a ton of air.

[Alex Zeller]

I ran PEX throughout my shop (It's rated for over 200psi and 250psi burst). I had lots of 1/2" stuff left over from my heating system. The only place I noticed a problem is with my airgun. For that I have a air fitting next to the compressor above the sediment trap on the 1" line coming down. What you need to remember is that the air fitting that will go on your tool most likely will have a smaller inner diameter that 3/8". I specifically found some Milton connectors that were larger than normal. I also bought a 1/2" ID air hose. It's noticeably bigger than the normal 1/2" air line (which is 3/8" ID) that is used almost everywhere. So you really have to ask yourself this. Is 3/4" pipe really going to make any difference when my air fittings are 1/4" id and the rubber hose I'll be using is 3/8" id?

BTW painting with an air gun uses almost no air what so ever. Look at the tip of the gun. See how small that hole is where the air comes out? Must paint guns sold today are HVLP (high volume, low pressure). Save your money and get a really good air drier. Or if you are handy you can make something that will boost the standard driers. For example cooling the air down after it leaves the compressor by filling up a garbage can with a 25' of hose in it before the dryer will make a difference. The one I have uses what can be best described as an AC unit (uses Freon to cool the compressed air).

[Darcy Warner]

Dryer is just a dehumidifier.

[Rick Alexander]

I have a 24 x 32 shop with a 1/2 inch line going 3/4 around the shop (front door is a 18 foot door so didn't need it there). Like others have mentioned - 1/2 inch seems completely sufficient. More fittings available at my local store for that size plus cheaper overall. Great product - no leaks after 3 years use - great investment.

[Jim Andrew]

I installed rapid air 1/2" a few years ago, bought 2 sets, and it is fine for my shop. My air hose is 3/8", so why would I need a large line? And I have a single cylinder air compressor. It is even big enough to run my tire machine.

[Ole Anderson]

For running normal air tools up to a 1" rattle gun, 1/2" will be fine unless you have crazy long runs of pipe. The only thing I can think of that might need more air is a big sandblaster, but then your compressor will be the limiting factor. I just installed the 60 gallon Kobalt 3.7 hp compressor in my basement shop which cycles 135-175 psi. I come off the compressor with a 1/2" filter/regulator set at 120 psi so my system always sees 120 psi at the beginning of the run. After that I split to two runs of 3/8" rubber hose. Old school, but it works fine for me. I have a second regulator in the garage less than 10 feet away prior to my 3/8" hose reel that I typically keep at 100 psi.

[John K Jordan]

My air hose is 3/8", so why would I need a large line?

It wouldn't apply in your case but might help some people - a larger line acts like a reservoir to give a bit more volume. When constructing farm buildings far from power I put a portable pancake compressor near the power and ran 100s of feet of air line. We could operate several air guns a little longer before the compressor kicked in. Of course, it took a like longer to pump back up to pressure then. And since the volume of air has inertia, an application with a high demand can pull air from a larger line quickly with less pressure drop.

I've read of some industrial installations where air was being used at several stations at once. The design used a larger diameter pipe connected in a ring configuration, a big loop. This way no user was at the end of the line and "Because air is supplied to any piece of equipment from two directions the velocity is halved and the pressure drop reduced." (From https://www.cedengineering.com/userfiles/Compressors%20and%20Compressed%20Air%20Systems.pdf , pg 54-55) And from the CEATI Compressed Air Handbook: "A single loop of pipe can reduce pressure differential by 75% compared to a single pipe of similar size. Multiple loops can further enhance the flow of air."

No need for this in my little shop!

JKJ

[Mike Cutler]

I installed rapid air 1/2" a few years ago, bought 2 sets, and it is fine for my shop. My air hose is 3/8", so why would I need a large line? And I have a single cylinder air compressor. It is even big enough to run my tire machine.

Jim

Air friction losses and differential pressure drop across the actual hose itself.
If you were to put a gauge at both ends of an air hose, you would see that they both have the same pressure indicated. At the moment the trigger is depressed on an air tool, the pressure closest to the tool will drop, and so will the pressure at the other end of the hose. It's almost an absolute guarantee that the pressure gauge closest to the tool will have a lower indicated pressure than the gauge at the other end. This is the representation of the inability for a smaller diameter hose, to pass enough air volume to maintain pressure.
In real life, most people would never notice this drop. If you're running impact drivers that require high breakaway torques, you will. John has a farm,and I am fairly certain that if he's doing his own maintenance on tractors, back hoes, and front loaders, the breakaway torques he will need just to remove a wheel will exceed a 1000ft/lbs.
Whenever I hear someone say that they need a 175psi air compressor, to run a 120psi air tool because "it works better". I am just about certain that there is a small diameter air hose, on a reel, somewhere in the equation.
Most people will never see the need for a larger diameter hose. 1/2" airlines , a 3/8" hose, with 1/4" air fitting will do most everything a person would want.

[Bill Dufour]

Your 1/2 pex is really 3/8 pipe size.

[Jeff Monson]

1\2" rapid air is what I have in my home shop, never had an issue. I dont like working with 3/4" as we have that at work. Much more durable than the 1/2" but for home use I'd just go with that. just my .02