I was moving my air compressor the other day and had to disconnect the air hoses. When I plugged one of the hoses back in, no matter what I did, I couldn’t make an airtight connection. I figured the coupler had gone bad, so I turned off the compressor and decided I’d pick up a new coupler the next day.
I’ve had problems before, with buying quick connect air fittings. Once, I purchased a male plug that I thought looked identical to every other plug I had in my garage — I even compared it to one I had brought with me to the store — but after I bought it home and tried to plug it into the coupler on my compressor, it just wouldn’t lock in place. Yet it worked just fine in another coupler I had. I just attributed it to differences in manufacturers and moved on.
To make things easy, this time I bought a “universal” coupler and figured it should work. I got home, replaced the coupling, and had no problem inserting the plug. Still, I was bothered by my lack of knowledge about plugs and couplers, so I started researching the topic, starting at Stuart’s post about compressed air nuisances, and quickly got lost down a rabbit hole. I figured if I was confused, I couldn’t be the only person — I’d write a post that would hopefully straighten it out.
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What I found is that there is a lot of misinformation about what types are equivalent. I browsed several forums and found people contradicting what manufacturers were saying, and so I decided I’d only use data from the manufacturers of these fittings, rather than trusting what any individual claimed.
Most couplers look the same on the outside, so let’s look at plugs first.
Plugs
First off, there are different basic flow sizes, such as 1/4″, 3/8″ and 1/2″. This doesn’t refer to the size of fitting on the end of the plug, but rather the volume of air the plug can handle. For our purposes, we are going to concentrate on the 1/4″ basic flow size fittings, as this is the size that you are going to run into for most home and light commercial use.
Chances are you are going to run into either industrial or automotive type plugs in the 1/4″ basic flow size. They are the ones you are going to find at the big box stores, like Home Depot and Lowes. You might also run into ARO plugs in the 1/4″ basic flow size. There are different industrial, automotive, and ARO plugs for larger basic flow types like G-style for the industrial, but we won’t go into that here.
There are two other type of plugs in the 1/4″ basic flow size you might run in to: V-style (high flow) and Lincoln*. I did not find these styles at any of the big box stores, but Northern Tool carries V-style and Menards carries Lincoln style.
*From here on out, everything everything should be assumed to be 1/4″ basic flow size and each style will be called by its most commonly used name in bold.
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Thank you to Greg for his insights and help in clarifying this part!
Above is an industrial style plug. They can be called by a few different names. For instance, this can be also be called a Milton plug, but more correctly it is Milton M-style. It is also known as type D or I/M style.
To make it even more confusing, Milton has a D-style plug, but that isn’t necessarily compatible with this style.
Above is an automotive style plug: Also know as a Truflate, Type T, or C-style.
The V-style plug is a high flow style plug, it is similar to an industrial type plug, but it has a larger opening to accommodate higher airflow as you can see above. The photos here show a Milton V-style, but other companies also make high flow plugs.
Then there is the ARO plug, above, which can also be called A-style or type B.
Finally there is the Lincoln style shown above.
Couplers
Each of the different plugs has a matching coupler. If you have that specific coupler, chances are it will only accept a plug with the same style. Although I found some industrial only style couplers will accept V-style plugs, I wouldn’t count on it.
The problem is most of the couplers look the same on the outside, so they are harder to identify than plugs. There is an somewhat accepted way of identifying them via counting the number of thin and thick “stripes” on the body of the coupler, but it’s pretty useless because not everybody adheres to it.
Also unless you have two couplers from a single manufacturer, one company’s thick stripe can look like another companies thin stripe. Plus you have to remember which marking are which style and the plugs don’t have matching markings.
Then there are universal couplers. Some claim they only work with industrial and automotive style plugs, but others claim they work with industrial, automotive, and ARO type plugs.
There is also the Milton V-style coupler. It is designed to be the high flow mate to the Hi-Flow plug. Milton says that they are also designed to accept A, T, and M style plugs (if you are paying attention that’s ARO, automotive, and industrial plugs).
I found that another company’s high flow coupler would also accept automotive and industrial plugs, but that was in store and not under pressure. I don’t want to make a claim if I can’t find documentation.
I’ve also read that some universal couplers are not as reliable as single-style couplers – that they are more prone to leakage especially if there’s sideways pressure applied to the plug.
Another feature of couplers is that they can be either manual or automatic. You can tell the difference by looking at the photo above, the automatic coupler has the sleeve pulled back when there is no plug inserted.
With a manual coupler, you have to pull back the sleeve to insert the plug and make the connection, but with an automatic coupler you just have to push the plug into the coupler and it will automatically make the connection. With both types you still need to pull back the sleeve to release the plug.
As far as I can tell, only universal and V-style couplers are available in automatic styles.
Color-Coded Connections
Several manufactures have recognized how confusing the many different types of plugs and couplers can be and have adopted a color-coded system.
Milton has the ColorFit system. Here’s the chart:
- Industrial (M-style) is red
- ARO (A-style) is green
- Automotive (T-style) is blue
- V-style is purple
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Legacy has their ColorConnex system.
- Industrial (Type D) is red
- Automotive (Type C) is blue
- ARO (Type B) is green
One advantage Legacy states for using their color coded system is that you can quickly distinguish your oil-less lines from your oiled lines. Say you are using an paint sprayer – you don’t want a hose with residual oil in the line, and so you might pick green for all paint spraying equipment and use red for everything else.
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Summary
So what’s the takeaway from all this? Chances are you are probably using either automotive or industrial style plugs and couplers. If you want to be safe, you can purchase a universal coupler and you should rarely ever have a connection problem.
If you want to be absolutely safe, my recommendation would be to pick a more reputable manufacturer’s fittings and just stay with them, preferably a manufacturer that you can buy locally so you can quickly replace a coupling if you need to — either that or make sure you have a few spares. The reason for this is because plugs and couplers from the same manufacturer are more likely to fit better and be less prone to leakage than mixing brands, styles, or using universal couplers.
Or if it’s really confusing, and you have to use different styles of plugs and couplers, you can always use color coded ones.
Personally, I’m going to slowly switch over to Milton V-style plugs. It’s a solid brand that I can get locally, V-style connectors have less restriction, and the couplers work with the most different styles of plugs.
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What types of quick-connect couplers and fittings do you use? Why?
Hilton
Yes it is confusing isn’t it. I use m-style (industrial or red) and that seems to work.
We’ll probably get serious war stories about this topic and one must wonder why no ‘standard’?
Alex Thomson
Our local NAPA store has an excellent selection of all styles. For some reason, I standardized on the Lincoln style years ago. I think probably because that is what we had at the farm at the time when I worked there. I know that some couplers that come with imported tools are something unto themselves.
Cam
I purchased a flush gun canister that came with the weirdest plug I’ve ever seen lol
Joshua Latham
I use Milton V-Style couplers and V-Style plugs on my impact wrenches and other hi-flow tools. Then just regular industrial for all my nailers, they work fine in the V-style coupler.
Robert
So let me ask. The leakage you spoke of, was that just a small air leak or one that caused you compressor to cycle every few minutes? Should fittings not have any leak what so ever while sitting idle?
Benjamen
It was an audible leak. I could hear air escaping from across the garage. I don’t know how often it would have caused the compressor to cycle, but it was definitely unacceptable.
Ideally, I don’t think you should have to live with any leaking from a coupling, that said, I have been living with a few very slow leaking couplings for a while — slow enough so that the compressor only cycles every 4-6 hours. (I’ve found it’s better to have my compressor cycle every once in a while otherwise I have problems with the valves inside the head sticking.)
David
Hello Robert,
When your fittings are installed correctly you will NOT have any leaks.
I own a custom picture frame shop and I have 3 work stations that have Blow Guns, another station with a pneumatic CNC Mat Cutter, another station with a pneumatic V-Nailer and another station that I use a HVLP Paint Sprayer and an Air Chuck to inflate tires. Also one of my stations that has a Blow Gun, A few times each week I will connect and use a pneumatic Crown Nailer and a pneumatic Finishing Nailer at that station. I have a total of 6 pneumatic hoses connected to my compressor using a manifold and I leave my compressor on 24/7 with no leaks or problems.
I use the M-style, sometimes called Industrial or the Red Color Coded style plugs and couplers. Always use teflon tape when you install each plug or coupler.
David
Andrew LB
While not as extensive as yours, i’ve got a 2 hose setup with all V-Style high flow connectors and nothing leaks. Compressor is left on 24/7 and has been that way since 2006 or so. All i added was a ball valve downstream of the regulator followed by a hose (i’d use pipe but earthquakes.. meh) that goes up about 10 ft, then back down to my Desiccant dryer where i have it split to each hose. a ball valve is on each of those air outputs in case a hose breaks i just shut off the air to it and use the other.
The reason why i run the line up almost to the ceiling and back down is an old trick I learned from a famous car painter here in SoCal whose name ill omit and the purpose is to condense moisture out of the air before it gets to the dryer, so it lasts a lot longer.
Kinda like this: https://www.stewmac.com/freeinfo/i-5436/5436_5compressor.jpg
Ken Graham
That is a good idea about the high airline to condense moisture.
I notice in Mexico they are starting to sell Pex with Aluminum core in which would be good for Water Lines and air lines. They also are using the AlumaPex with a black and yellow covering for propane lines. The air conditioning place is also selling it with special fittings to replace copper, cheaper and less corrosion for beach locations, also probably less risk of theft due to its non copper makeup.
I purchased a new air compressor in Mexico, 3 horspower electric Truper brand, small tank for portability. The area is humid so it has quite a bit of water in tank every day it is used and I was disappointed to see it come out quite rusty indicating the inside of the tank was not painted. I had some epoxy paint and so took out the bottom bleeder valve and with compressor on its side poured a mixture of epoxy paint with thinner making about a pint or 1/2 litre into the tank then used a plug and righted the compressor and rocked it around in hopes of coating bottom of the tank. Not much drained out after and the next day I put a small ball valve back in for easier bleeding of the air tank. The 1st couple tanks of air I just bled out through the bottom ball valve, they were quite smelly with the thinner so be careful of fire hazard. Since then any moisture drained from the tank no longer has the rusty water come out so I assume my tank will not be rusting out from the inside.
(As the compressor was going to be tipped over I took it as a good opportunity to replace the oil as well)
George P
Andrew, thanks for sharing the tip on running your lines up and then back down. I just bought a house that was originally owned by a guy that built custom cars. Many of the runs have the drain ports at the bottom but most of the lengthy runs are very flat. I like the idea of sloping them to allow the moisture to fall back to each drain port.
Thanks!
Emilio Gonzalez
IR has air lines that have special air flow vents that direct water away. You can configure your modern air lines any way you want.
Herb Glum
The 2 industrial couplers (sockets) on my 15 year old Eagle Compressor finally started leaking because the rubber seals got hard so I decided to buy new universal couplers to replace them. I purchased and tried two each couplers from Home Depot, Lowes, and McMaster Carr (each company only sells one brand of 1/4″ universal couplers). They all have noticeable leaks when the plug is inserted, although the McMaster couplers don’t leak as much as the others. I’ve also tried several different plugs, old and new, industrial and auto style, in all six of the couplers with the same results. I think that there is just something wrong with the universal coupling design. It is really handy to have but the constant hissing from the leak and compressor cycling (~ 15-30 minutes from a 20PSI loss in a 25 gal. tank) isn’t acceptable to me. All of these leaking universal couplers were returned and I’m back to industrial only couplers.
brent
There is rubber seal on the inside of the female coupler as well as balls to hold the male coupler. Your seal needs to be there and in good condition. The more balls you have holding the coupler the better.their are 3, 4, 5, and maybe 6.
Johann
I had no idea about the different varieties, but that now explains why I’ve had trouble in the past.
The best thing about standards is that there’s so many of them!! /s
Peter Fox
As a good friend said to me once the problem with standards it the second “S”
AngryDrumGuy
Aside from the higher flow fittings, I have no clue why there are different types like automotive or industrial.
I’m running industrial on an impact wrench I use for lug nuts. It works, so I have no idea why I’d need an “automotive” style.
Can anyone elaborate for those of us who’ve never used anything beyond nailers and an impact wrench?
MtnRanch
The good thing about Universal is that it leaks equally with all fittings
John
I disagree with Legacy’s suggestion of having dedicated hoses for oiled and oil-less lines. Different colors would require you to use two different styles of plugs and couplers. If your compressor has a quick connect hose couple installed on it, you would need to change this out each time you wanted to switch between oiled and oil-less hoses. Also, if you’re concerned about oil contamination when painting, a dedicated hose with unnecessarily redundant plugs and couplers won’t make much difference. An oil-lubricant air compressor will blow a fine oil mist through the hose and into your paint spraying equipment. Same is true if your compressed air system has a tool oiler installed. Your best line of defense when painting with compressed air is to use the right type of filters and dryers to remove particulates, oil and water.
Benjamen
If you are the only person using the equipment, maybe you are right. But I think it would be an additional impediment for somebody grabbing your sprayer hose because they need an extension. The last thing you want is to grab your equipment and accidentally start spraying oil all over because Joe used your air hose.
I think to be safer, you choose a style like Lincoln so that it wouldn’t work on a universal coupler. Also you could use a dedicated compressor or plumb a separate line from your current compressor with a dryer and filter just for the sprayer.
Gary
I disagree with your disagreement ;). I have a shop setup with 2 lines coming out of the compressor; the one line has an Oiler and goes to industrial style plugs and connectors for all my air tools; the other line has an oil and water remover/air dryer System on it to fit my automotive painting setup. I picked ARO connectors for that line and all the paint guns/blow guns (or any tools that doesn’t need oil). This setup ensures that you cannot grab a tool/paint gun and use it on the wrong line as it won’t let you do it.
And; yes; there are too many standards out there. Great write-up!
Cheers
rmkilc
Industrial on everything. Automotive style can go away as far as I’m concerned.
Larry K
Same here!!
Charles carlisle
Exactly just keep it simple
fred
To expand the discussion, one might consider other alternatives like:
“Safety” Air Couplers – with push button or other release mechanism
Swivel Couplers – either male plug style or female style
Swivel fittings
2-Way T-Couplers
3-Way couplers (Tripod style or in-line style)
5-way in-line couplers
Brian
I LOVE the safety/push button couplers. They are so much easier than having to run all the air out of the hose or going deaf from releasing a connector under pressure.
Joren
I agree the pressure release ones are very good. Keeps the whipping / danger down from a high pressure release when disconnecting hoses under pressure.
Much better option when starting a shop up, and selecting fittings, than after!
kent
I bought fitting for my air tools, and all was good in the world. I recently moved closer to home, and have been using my dad’s shop.
It turns out that he uses a different fitting than I do. I’m guessing that it’ll cost me $100 to change over all my tools, hoses and compressor.
Mopar
Or you could make up one adapter
fred
You might like to use a short “whip” hose as the intermediary link. Your style female coupler (regular, swivel or safety style) at one end – and your Dad’s style male plug at the other.
Brian K
Get a coupler that fits your plugs and a plug that fits his coupler. Mate the two together and you can go between then.
Yadda
Great topic! I learned something today!
MtnRanch
After accidentally standardizing on “automotive” style years ago I’ve have no complaints – also it keeps most others from using my stuff.
Is there any benefit to “industrial” vs. “automotive”? I haven’t found any.
Greg
With all due respect, to avoid confusion, I think you should focus on the two variables for couplers/plugs in a generic format – coupler body size and plug style. To that end, there are generally three coupler body sizes – 1/4, 3/8, and 1/2 (size sort of approximates the internal bore diameter but not really) with the four most common plug styles being industrial, automotive, ARO, and Lincoln (there are others but you will probably find these the most). You can get most of the coupler body sizes in each of the plug styles. Milton’s letter naming denotes both a specific body size and style. As an example, Milton M is an industrial style in a 1/4″ body size. Milton P is an automotive style in a 3/8″ body size and so on. Milton’s V is a 1/4″ body coupler with a larger diameter bore giving more flow (looks like industrial but bigger diameter bore than industrial). As you found out, some couplers can fit multiple style plugs within the same body size. I’m not aware of any coupler and plug of different body sizes being able to join. My advice would be to pick the body size that gives you the airflow you need, and then pick the plug style that you can easily find. Industrial seems to be the most common with automotive a reasonable substitute. 1/4″ body and to a lesser extent 3/8″ body are the most common. careful though, the couplers increase drastically in size going from 1/4 to 3/8 and 3/8 to 1/2
fred
The bulk of construction-trade pneumatic tools in the US seem to come with a 1/4 inch NPT female inlet – some with an industrial male quick connect plug supplied.
Outlet couplers on portable jobsite compressors also seem to be mostly 1/4 inch Industrial. On some occasions, you will buy a tool with a 3/8 inch female NPT inlet. While airflow will be decreased, much of the time, you can get away with using a 3/8M to 1/4F NPT bushing – and then go with a 1/4 inch plug and hose. Should performance degrade though – you may need to move up to a 3/8 hose and fittings.
Of course for heavy duty tools – e.g. jackhammers our hoses were 3/4 or 1 inch nominal – with Chicago (aka Crowfoot) couplings
Benjamen
Sorry you do not appear to be correct. It might have been that way once, but Milton no longer follows that format. And as far as I can tell nobody else does.
For example Milton has 1/4″ and 3/8″ fittings in both P and V styles they have M style in 1/8″, 1/4″, and 3/8″. Here’s one of the links: https://www.miltonindustries.com/couplers-and-plugs/p-style.html?dir=asc&order=sku
It may explain one of the reasons why different styles have different names though.
Benjamen
Please disregard my comment above. I appear to have misread your comment. I thought you were saying that Milton P-style meant 3/8″ body size only.
I have a chart from Milton that does show that P style is related to the automotive T-style, but it’s thicker and has a longer nose.
Here’s the chart:
http://web.archive.org/web/20101217232235/https://miltonindustries.com/uploads/Page_36.pdf
To your point about breaking it into 2 variables. I didn’t want to further complicate a complicated issues.
Greg
Milton’s current catalog is here:
https://nebula.wsimg.com/2c8c2c6b3e8277b809142ce502bdb25c?AccessKeyId=281F9A89657DD9338EBF&disposition=0&alloworigin=1
But that is the thing, there really is just two variables. Body size and coupler style. Study the Milton catalog and you will see that each Milton letter is simply their code for a specific combination of body size and plug style. Milton M is always going to be a 1/4″ body in an Industrial style. Someone else’s 1/4″ body in industrial style will plug in and work with a Milton M.
If you don’t believe me, look at pages 18-19 in the Milton catalog where they cross-reference everyone else’s couplers/plugs with their own. It only seems complicated because everyone uses a different name for the same thing.
Benjamen
Great chart, I wish I had found it before, but it still wouldn’t have changed the way I wrote this article.
If I was writing the post from the perspective of — I have a system I want to design with certain constraints like how much flow I need — then body size would have factored in. Otherwise body size is not a relevant variable. It is completely dependent on coupler/plug style, it is just another dimension like length of the coupler or shape of the ridges.
I wrote this article from the perspective of an average guy that already has an air compressor or compressed air system and wants to match the style so they can plug their tool in, buy the right connector for their new air hose, or replace a component. In that case they are going to know the thread size and they are going to have a certain coupler type that they need to identify. Body size is not going to factor into that, because it is already part of the information you get when you know the style of plug or coupler.
Greg
Body size is independent of the coupler/plug style so I don’t understand why you feel it can be ignored. If someone wanted to go and get new couplers/plugs to use in an existing system, you would still need to know what body size couplers/plugs you already have (in addition to the style) so they fit with everything else. Ignoring style for a minute, if you have an existing 1/4″ body system of couplers/plugs, and buy a 3/8 body plug or coupler, it isn’t going to work with the existing system (even if you got the style variable correct).
The most popular coupler/plug style, industrial, comes in all body sizes (1/4, 3/8, or 1/2) so how can it be ignored? Using Milton’s naming convention, an industrial style coupler/plug in 1/4 body size is “M”, an industrial style coupler/plug in 3/8 body size is “H”, and an industrial style coupler/plug in 1/2 body size is “G”. If you buy and “H” to work in an existing “M” system, it won’t fit.
That being said, 1/4 body size is far more popular than 3/8 or 1/2, so chances are 1/4 body size is what most people use and what most stores will have. ie, availability of parts reduced the potential mismatch of this variable. But it is a variable none the less.
In summary, there are two variables (body size and style) and both need to match for compatibility, whether this is a new system designed from the ground up or buying new parts to fit into an existing system.
Benjamen
I can’t reply to your last post. so I’m replying here.
Thank you for keeping at me, I think I finally understand what you are saying.
You are saying if you use the term INDUSTRIAL, at least according to Milton, it can mean M, H, or G.
The terms INDUSTRIAL, AUTOMOTIVE, AND ARO are classes — groups of types. You need to specify the body size for these type to be completely clear even though many places assume 1/4″,
But if you state the type like M, G, or H, you do not need to worry about body size because that’s part of the definition of the type. I was lost on that detail and didn’t see the larger point you were making.
Alright, now I need to think about how to submit an update to the article to reflect this.
Greg
I think you got it-Industrial, Automotive, and to a lesser extent ARO and Lincoln indicate a specific type of plug style/shape (there are others too but these are most common) Typically, you can get any style/shape in three basic flow sizes -1/4, 3/8, and 1/2. I was using Milton’s naming (M, G, H, V, etc.) only as an example of a widely available product (plus you used it too). Milton’s naming convention has both the body size and the coupler/plug style included so it is a little unlike other manufacturer’s naming. Unfortunately, people use it like it is its own style when in reality a body size and style are buried within it. The primary point I was trying to make is that if you focus on body size and plug style as the only two variables, it makes everything easier to understand and you can compare across different brands.
I initially commented because when I read the article, it wasn’t what I was expecting and seemed like you were confused as well. I’ll leave the updating to you 🙂
Keith Valley
My problem isn’t plugging it, it’s finding the right size and type of fittings just to get to the plug. It’s my understanding, only from reading this, the 3/8 branded on my hose is not the size of the fittings. I can finally go to the store now. However the store is littered with NFT, PSI, MOQ, etc if you make to the plumbing section past the automotive section. The fitting I’m trying to connect is threaded female that looks like she’s pregnant and diolating. Hopefully that makes sense to someone. Even if something is the right size I can’t get it to tighten down.
Koko The Talking Ape
I know I’m replying a few years after the original post, but…
Respect to Greg for his knowledge and clear, civil explanations.
But even more respect to Benjamen. It isn’t easy to keep one’s ego out of these discussions, and sometimes people just can’t, perhaps through no fault of their own. But Benjamen could and did. A rare quality. People like Benjamen should be in charge of everything.
Mrkoolio
Yeah…..thanks for that. When I was coaching, people would always come up and offer their advice or thoughts on how I could be doing things better. That’s why I always made sure I wore a hat and when they started to do this I would take off my hat and hand them the hat. Of course, they would ask me why I was handing them my hat. I would say, “well, it sounds like you have a lot of good ideas about being about being the coach and it actually takes a lot of time and effort and I’m really busy ….so I have no objection to you being the coach… why don’t you take over and I will gladly go over and sit in the stands and quietly watch you work. And then I would wait. Stunned silence. Their feet would shuffle. What did they would say something like, “oh well I wish I could but ……” and that is about as far as they got…. because at that point I put the hat back on my head and I said, “well, in that case, there can only be one coach… and right now ….I am it.” And then I walked away. Sometimes those same people would forget our prior conversation and approach me later in the season and as I saw them coming up to me with a question I would start to take my hat off and offer it to them and they would just turn around and walk away.
And with that, I say Greg if you want to be the coach …why don’t you write your own article and insert whatever facts you believe are helpful and relevant and then many other people will write you and tell you how your article isn’t as good as they think it should be. and then you’ll know exactly how the author of this very informative and helpful article felt when He read your post. We will be waiting.
A W
There’s one photo between the “Aro plug, below” and the “Lincoln style, above”. I think something’s missing.
Benjamen
Good catch, it’s just a mislabel, there’s nothing missing.
I originally had a few photos below as I was writing, but changed them to above the text for consistency. I just forgot to change the label and Stuart didn’t catch it either. I let Stuart know to fix it, since I can’t change a post once it’s been published.
Noah
This is all very interesting, useful, and still confusing.
Diamond Dave
Anyone have recommendations as to a good and readily available brand name to use for connections? I have in the past purchased them from everywhere…sometimes singular and sometimes packaged in a kit and there are definite differences between them. I have a few quick connectors that leak no matter where you mount them. I also look for at least 4 ball bearings in the quick connectors vs 3 ball bearings which seem to leak most of the time when side presssure is put on them.
RKA
Milton. All the locally available junk I’ve bought has leaked in 6 months or less. I switched over to Milton and have less problems with them. Unfortunately since they aren’t locally available, I keep a small stash handy in case a fitting needs to be swapped or a new tool sneaks into my toolbox.
Raoul
This. Another good thing about Milton is every fitting is stamped for identification. Anything not marked you’re guessing. Maybe contact Milton for their supplier list. I have a small family owned supply house nearby that has had them for decades and they are quite inexpensive.
FD
… I’m more confused than ever now …
Diamond Dave
Also, anyone have good luck with the newer Aluminum type fittings? Almost bought a set on Amazon but too many bad reviews.
Bruce
Air hose fittings are by far the worst offenders for shop problems. My shop is industrial only fittings. I only buy quality fittings (usually the red ones you’ve shown above) and I still have leaks every few weeks. The tool gets shoved around the bench and the tiniest scratch on the fitting causes it to leak. If it’s a big enough scratch it damages the seal inside the female coupler and pretty soon that is leaking. It’s bad enough that I leave a couple of crecent wrenches near all the air stations on a special hook. That way you can swap out a bad fitting quickly and with minimal fuss.
Raoul
I switched to Milton only about 30 years ago and I don’t have problems. I literally have Milton stuff that is 30 years old and still does not leak.
Ken Graham
I wonder how well 3/8″ stainless steel pressure water fittings would stand up . They are reasonably common so not extremely expensive, good for 5 to 6000 psi vs 250 psi. As they are heavier duty their airflow might not be as good as a 3/8″ air fitting.
Will
Pressure washer fittings would be like a high flow version in the 3/8 body. They have a substantially larger bore. There is one draw back the couplers are open center so you would have to shut a valve somewhere when removing a tool
Ken
You are correct that water coplers dont block the line when uncoupled. I found a use for that idea, I purchased a Sand blast attachment for a Karcher pressure washer on Amazon, it has a 1/4 ” pressure washer attachment, disconnecting the included Karcher washer adapter I went to 1/4″ female water coupler then ball valve then 3/8 male air coupler then attached to airline. The large vacuum sandline is allowing me to piick up heavy liquids for spraying. My current project was a white cement paint made by mixing 1 part white cement with 1 part water by volume, this I have sprayed on 20 year old red tile roof as well as some red metal roof awnings. The white cement reduces measured surface temperature by 25 degrees Farenheit. Also experimenting with spraying over a white Acrylic Latex roofing compound on a almost flat cement roof. There is no temperature drop on that but I am hoping by blocking UV rays I can extend life of the waterproof coating. Normally only good for a couple years in sun but lasts indefinately under the old roof tiles that were on a sloped portion of roof.
Need I say the house is much cooler now here in the Tapachula.Info tropics.
Dave
https://www.miltonindustries.com/
Milton makes some good items. Watch their site, around Christmas they had a ‘flash sale’ with a 5piece set for $4, when factoring in shipping and buying 5 sets it came out to about $1 a piece. Better price than the stuff at HF or HD.
fred
BTW – I believe that most of the Home Depot (Husky Brand – UPC Prefix 045564) ) fittings are made by Campbell Hausfeld in China. I believe that Lowes – Kobalt fittings (UPC Prefix 879686) are sourced from Shining Golden Yida Welding & Cutting Machinery Manufacture LTD in China.
Most of the Milton fittings I have – were made in the USA as of a few years ago. I also have Amflo (as in Schrader-Bridegport a Tompkins PLC -Gates Rubber Co.) fittings that were made in Taiwan. My most recently purchased Coilhose Pneumatics safety couplers – work well and were made in China.
Hang Fire
I found a single cheap import coupler was killing airflow. It was a debugging process to figure that out. I had not had problems before buying a 1/2″ impact wrench, but I had just “upgraded” my hoses and fittings in anticipation of getting it, including adding the problematic coupler.
I settled on the GuardAir High Flow fittings, which seem to be their own standard, because I got a bunch on sale. Since then they’ve proven to be more expensive, but I’m already past the initial investment/expense. If I were to do it over again, I would go with the Milton V. My little 10 gallon tank worked fine for the 1/2″ impact, it now hit really, really hard. (I have since upgraded the compressor/tank).
MacLean
Now how about an article on hoses and reels? How about best practices for oiling tools? How about recommendations for built in shop systems like RapidAir or can you get away with pex or PVC? To drain or not drain after using your compressor and options for inline dryers. Oh the articles are endless and the misinformation out on the internet is prolific.
I’ve primarily used Harbor Freight industrial connectors. Had a couple of minor leaks but no trouble in 20 years.
Stuart
That’s a month of work you’re asking for. =) Some of those topics we can consider tackling.
For built-in air routing, I have RapidAir bookmarked for my own potential use.
PVC? NO!!!!
PEX: I’ve seen some people use it, but have also seen some conflicting opinions on the matter. Personally I’d go the RapidAir route for simplicity and the ability to seek guidance or troubleshooting help if needed.
Oiling tools: User manuals usually have maintenance schedules and guidance about this.
Draining compressor tanks: User manuals usually have guidance on this as well. Many/most (if not all) portable air compressor manufacturers say that tanks must be drained after every use, and I’ve seen stationary compressor brands say that tanks must be drained daily.
Hose Reels: I haven’t tried them, but would consider Flexzilla, Tekton, or Goodyear.
fred
You might also consider automatic drains for your stationary compressor and appurtenances (like air filter, molecular sieve, dryer),
Automatic inline oilers for shop use are also available.
My recommendation for hose reels is Coxreels
We had many overhead (single and ganged) and wall mounted reels from them that gave us excellent service.
fred
Here’s a link:
http://www.coxreels.com/reel-selector.html
MtnRanch
Thank you “Greg” for the link to the Milton catalog, it’s an education in couplers by itself. I see some changes coming in my shop air setup.
The good thing about standards is that there are so many to choose from.
Alick
Interesting that two of your three examples are uncommon enough in the UK that I’ve never seen them before. Only the middle “industrial” fitting is commonplace (pretty universal on cheap imports).
If you use QR fittings professionally, a very nice design is a female fitting that will release pressure from the tool and coupling ( the supply hose holds its pressure), before the fitting will physically disconnect. It’s an expensive but neat safety feature and users like it.
RC WARD
Great article! I had no idea there were so many types of air fittings, I agree with the colored fittings , that should be a mandatory rule when it come to these things. What a mess
Nathan
Sadly I have nothing to point to for this and my google fu seems to be off today. but the “Automotive” style air fitting is designed around the pneumatics for on road trucks and the like. I want to say they are designed around a pressure limit – and breakaway force in an accident.
Also to prevent the use of non rated connections as others will leak if used with a singular automotive connector.
IE you can’t cheap out fixing your trailer and get a 2 dollar fitting from HF to fix the air brakes or air ride on your equipment – you have to use another automotive style fitting or it will leak too much to work correctly. Or just not fit – something like that.
Again I can’t point to anything to support these statements but I believe this was the intended goal.
And most tool makers today use industrial standard if they put a connector on a tool – like your air nailers.
Sylvester Hope
Hello,
I was wondering is there a Chart you can buy or online pdf that you can print out with Style fittings and uses
Paul Rogers
I have looked at the specs of high flow automotive fittings versus Industrial and in almost most cases Industrial can handle much higher flow rates and designed to last longer regardless of the fittings of some automotive fittings appearing larger on some fittings.And in most cases all hardened steel construction with stainless steel balls and ring inside the couplings on both premium Automotive and Industrial fittings.Compare Ryco industrial fittings with the 3 different high flow models of Automotive fittings on offer.The Industrial has a higher pressure and flow rates compared the the high flow Automotive on offer.But most of the premium automotive fittings offer one hand operation when putting tha adaptor into the coupling.Larger hoses and fittings can also help(Boyle’s Law) whether in a home or commercial workshop.Also various fitting are made for up to 500 P.S.I which is over kill for the home workshop (125-150 P.S.I )but guaranteed not to fly apart.If redundancy is your goal consider that.Fittings come in all types;medical,food preparation ,auto so choose carefully because quality fittings aren’t cheap and especially if you want universal fittings.Carry spares!Beware though because not all brands of Industrial fittings do the much smaller sizes around 1/8” and 1/4”.Some do! I use 1/2” I.D Rubber hose in my home workshop 300PSI(900PSI bust pressure and crimped fittings.I haven’t had any problems in 25 years.(maintenance)Beware of galvanic when choosing your system components though not so much an issue with a lubricator if not spray painting.Use thread tape.
Martin Hocking
Wow,
Then you come to Australia where none of those standards apply and everyone uses “Nitto” and “Jamec” (which are shit).
Nitto is pretty much universal. Used by nearly everyone, has good flow and seals well. Came from Japan in the 70’s I think and has supplanted Jamec.
Jamec is an old standard, is restrictive and leaks. I’ve used it in the past, used to be everywhere. Rarely see it now. Old trucks maybe.
Neither of these look like the US standards, though “Industrial” does look like the Ryco style plug.
I’ve seen it at industrial suppliers, but I dont know anyone who uses Ryco – maybe Industry!
Vince
My biggest headache with air fittings (other than leaks) has been with coupler retaining balls rusting. I have taken a Milton coupler apart and measured the diameter of the retaining balls. Then I Googled to find a supplier of stainless ball bearings to replace them. You have to be very close on size. Too small and they will fall out. Too big and they won’t cooperate with the plug or the coupler sleeve has problems. So far I have not found a source for these. Any advice (other than to keep everything inside which is not possible at this time)?
Evan
The article and comments are an excellent discussion and have helped me resolve my years of puzzling over couplers and plugs. Now I know what’s out there and in my shop (and why) and what to look for. Thanks.
Eric
This was the most valuable article i’ve read in a very long time. Thank you.
Saighdear
Confused.com here in he EU lands as well! UK fittings. and when you think you can modify by soldering / brazing etc, NO! – that doesn’t work either. Whether they have odd threads or made of odd metals it’s sometimes stalemate and sour mae at weekends when you find these things out and can’t progress a simple testing job where you use these couplings on pressure test gear. ….
Cherie
Hi. I have searched everywhere and am hoping you can help. I have an Alita air pump aerating my pond, and it’s a bit too strong. I am running a 3/8″ inner diameter air line, and I am looking for an in-line bleed valve with barb fittings. All I can find are valves that *block* the air, but that would mess up my pump—I need to be able to control a steady release of a bit of the air before it reaches the end of the line. I’d be grateful for suggestions. Thank you.
Stuart
I know zero about what might be proper or safe for this application, but here is what I would research if in your shoes:
In industrial processes, I would look at an “inline flow control valve” or “exhaust valve,” or something of the sort. Or maybe an “inline flow control valve.” Or an “inline flow control valve with exhaust.”
Perhaps one option is to create a Y-branch and add a flow control to the “exhaust” side, allowing you to bleed off as much as ~50% of the airflow somewhere else.
Looking at the pricing of Alita air pumps, valves or regulators might not be an economical option. Before looking into pricey regulators and controls, you might want to contact the manufacturer of the air pump. Alita might recommend a smaller pump, but they might also have more application-specific advice on how to do what you want in a safe and economical manner.
Lindsay
Stuart is right. Try making a by-pass:
You put in a branch. One side goes where you want the air, the other venting to the atmosphere through some adjustable regulator.
Here’s how it works –
I use a bypass on a fountain to get precise control of its height without overheating the pump. The flow from a submersible pump goes to a branch. One side goes to the rose, the other (bypass) side through an inline valve into the pond. Closing the valve creates a back-pressure which increases the height of the fountain, opening the valve decreases it – but flow through the pump is never stopped.
Stephan
Thank you for this great article! I was a European Dealership Tech for 12-years and have a very impressive home garage and I literally had no idea, I did what 99% of people do, change the nipples and connectors until I found a set that worked. One thing I HATE is leaking air past the fitting, do you know of any high end top of the line nipples and couplers that have zero leak?
Larry K
This is a sorely needed article. Thanks Benjamin!
Now, please do an article on the oil and water filters that every compressor air tool system should have. Some are made for tank mounting and others are line end, pre-tool filters.
I’ve known a lot of tradesman that ruined their air tools for failing to invest in the relatively cheap, good quality tank or hose line filters.
I’m in Florida where the humidity is always high at night in winter and all day long in summer. I’m originally from Ohio where I worked many years as a commercial carpenter. But very surprised that many Florida tradesman in my area had no knowledge or training on the importance of filters for compromised air systems.
Best2u, always…
Skorp
… and it gets even better: I live in Europe now and tried to connect my European Tire Inflator to an American chuck and it didn’t take it. The European standard is “Hi-Flow” and my “American chuck” is Industrial… But the coolest part is that the European “Hi-Flow” standard chuck accepts both Hi-Flow and Industrial. Looks like the Europeans figured out a long time ago how to build their system more flexible to be able to use tools sourced from practically anywhere.
Rachel Frampton
My husband needs some twistable couplers. I’m glad you shared this; I’ll make sure to inform my husband about the V-style couplers because as you’ve mentioned, they are designed to accept A, T and M style plugs which is what my husband needs. It’ll be best if we’ll start looking for a store that sells different varieties of waveguide products. [redacted]
Jinny
I have a 6 gallon Craftsman compressor with the 1/4 quick connect and a 3/8 air hose.
what do I buy to be able to connect them together?
Stuart
Looking at the user manual for the newest 6 gallon pancake-style air compressor, it says:
Quick Connect Type 1/4″ (6.4 mm) Industrial
You’ll need to double-check the thread on the 3/8″ air hose, but it probably has an 1/4″ NPT threaded end that can be used with a matching 1/4″ NPT industrial fitting.
If in your shoes, I would try a kit that comes with a female-threaded fitting for the hose attached to the air compressor, and a socket with female-threaded end for the side of the hose that attaches to the tool, such as this Legacy kit on Amazon. It’s ~$6, which is only a little more than the price of the coupler by itself, and so I wouldn’t be upset over not needing the third fitting, a male-threaded quick-connect coupler.
From what I’ve seen, air nailers also have industrial-style fittings.
Evadman
I forgot to post this until I saw this post again. I switched over to mostly Miltion V-style colorfit plugs & couplers from industrial plugs (from random manufacturers) in mid 2018 based on the info in this post. I used the Milton high flow pro brand as recommended by Ben. I found out a few things during the transition and use.
The Milton connector will accept the industrial plugs from random manufacturers just fine. This meant I didn’t have to swap over all the plugs on my air tools immediately. I did swap my high flow tools, such as my sandblaster immediately. The sand blaster certainly appreciates the extra flow, as does my 1 inch impact.
The opposite is not true; the Milton plugs do not work in an industrial coupler. They will physically latch, but the connection leaks very badly, and you need pliers to pull down the industrial coupler to remove the plug. I had this happen all 3 times I attempted with different couplers. Looking at the milton plug, it was being bent/chewed up by connecting. Because of that, I immediately replaced all of the industrial couplers I had with milton ones.
The other issue I have is that the milton couplers are not as durable as the industrial ones I had. The purple part of the collar protrudes slightly higher than the body, and that collar seems to be the part that always drags on the concrete or asphalt and gets chewed up. I’m not a shop or anything, just a home user, so I don’t give them a ton of use, but they still get chewed up in a matter of months. It’s so sharp that I have to use gloves when connecting/disconnecting or I will cut myself (which I have done on accident).
Overall, I still really like them over the industrial ones I had, and zero of the connections leak, at least audibly. I would still make the switch knowing what I know today, but I would try to find a brand that had a more durable connector.
M
I believe the purples are aluminum, they make steel ones. Milton 760-1 1/4″ MNPT V Style High Flow Steel Plug – Box of 10 https://www.amazon.com/dp/B001O2ZID2/
Robert Adkins
Not wishing to sound like a Luddite but industrial is the only one I will ever use. I actually appreciate quality and innovation, but I prefer standardization. The industrial design is perfect but has room for quality and materials improvement if someone insists on paying more. I like and use brass, but I really can’t say I’ve had any problems with steel. I think I’ve run across 1 defective new connector in my 50 years of using air. All my connectors have been as reliable as a railroad spike.
chip
Have a male connector that has narrow thread. Which NPT standard thread doesn’t screw into a air gun. Were do you get a connector?
Ethan R Townsend
Great read, I don’t feel so dumb for standing in the store going WTF for about 30 minutes before buying what I think I need and will probably have to return!
Ken
I went to my local Harbor Freight looking for a new hose and air tool connectors. They are now producing a Milton knock-off branded “Merlin” in a 5-piece connector set (item 63557 at $6.49). It is an I/M style 1/4″ They have upgraded from a 3-ball latch to a 6-ball latch in this line. They still sell the unbranded items. They state it is compatible with Milton “M”, Campbell/Hausfeld “I/M”, Amflo “D” Camel “D” and Truflate “I/M”.
It is a step in the right direction.
Stephen Strum
I moved into a house where the prior owner had a compressor hooked up to a 220 20 amp receptacle with the pipe either soldered to or fixed with lockit to a plug that is not compatible with my air compressor coupler. All my couplers are pretty standard and fit the 1/4 inch Industrial Milton plug. Your article was really nice and educated me about terminology and finding ID information. Too bad that the couplers have nothing written on them. So with the above said, I measure the plug diameter and it is 1/2 inch.
With my inability to remove the 1/2 plug, a possible workaround is to fine a female to female coupler that would fit the 1/2 on one side and would allow my 1/4 Milton (industrial) to fit in the other. Is there such a coupler? I searched on Google but am worn out and frustrated. If not, my only other recourse is to call in a plumber and have him try to remove the plug or remove the entire connection to the existing pipe. I am sure that would end up costing me a few hundred dollars.
Any help you can provide is much appreciated.
Stuart
Are you able to provide a photo?
If you can identify the coupler size/style, you might be able to make your own custom adapter using a length of hose with the compatible couplers on either end.
Stephen Strum
Thanks for the reply. The only apparent way for me to share a photo is to present you with a Dropbox link: https://www.dropbox.com/sh/n4osnc9p59elgcr/AACsNRAix2EmOsYBBhiRLDsTa?dl=0
There is no identification of the plug in the “closet” where the prior owner’s compressor was. But you post above leaves me to believe that …
1. I might attach hose with clamp to the male plug end,
2. from the other end of the hose attach a 1/4 in IM coupler via the male end of a 1/4 inch plug in it. (jpg in shared Dropbox folder).
Is this doable? If so, I assume just go to hardware store and ask for compressor hose and hose clamps. This could be an easy solution instead of my calling a plumber or breaking a pipe trying to remove the existing plug.
If this would work that would be great. Let me know.
DRT
That’s not a plug for a coupler. That is a pushlok style barb. You force a compatible hose over the barb, and it doesn’t come off. If you can find a compatible hose, then your idea will work. To do this right, you should go to an industrial supply place, or perhaps Summit Racing (not hardware store). BUT, I think you would be better off by removing that old pushlok and replacing it with something simpler and cheaper, like a Milton or other brand coupler. Try a propane torch to heat and soften the pipe sealer which the previous owner used to seal the threads on that barb. Heat should do the trick. Good luck.
Stephen Strum
Thanks so much. This site provided much needed answers. I was puzzled why that “barb” did not fit any of the couplers I had.
Ken Graham
That is a simple barbed fitting, take the photo to a industrial supply type store or automotive or hardware may do, and they should be able to find a matching type fitting and then use a coupler to a fitting of your choice. They will also need to supply you with hose clamps and a 1/2″ hose capable of your air compressor output pressure.
Brad
So, the coupler with a very small I-M in the corner is what is called Industrial, also known as M (the M standing for the n in Industrial?), and is available in red, known as Type D? How clear!
I tried to repair my coupler on the compressor by turning the soft washer over, as suggested in top-level Google searches, only to have the balls fall out and get lost. So I bought a new one from Ace, Tefloned it up, and it leaks when the male M (for Industrial, also called D) is in and it still leaks!
Is this a deliberate scam on the part of Forney and other quick disconnector manufacturers, marketed by Ace, to keep us buying finicky products with confusing names that don’t work well?
Arthur Callahan
I knew all the different air fittings just not their names. I still don’t
Stuart
If that’s a question, could you please be more specific?
Amin
It looks like Nitto’s Hi-Cupla design is respected and copied by many manufacturers in Asia.
Harold Pritt jr
We’ve always used L style quick connections and I worked a lot of different garages seems like every were I’ve been I’ve always herd air leaks . Nothing more pesky than this to me being a mechanic and a welder! Your always looking for a noise and a air leak can cover up or causes difficulties when doing this . Like we have always used Lincoln or type L seems like we’re the only ones I have people give them to me because they know we use them . That is why I figured I’d post with all the years I’ve used them they haven’t leaked I’ve took them apart and looked at them and put them back together yeah most you can’t I’ve seen others take a seal pick and change the o ring . Now Lincoln don’t have an oring to wear out they have a 1/4 disc or rubber inside them and a long male tang that goes down in the coupler never had a leak! Only down side I’ve found rough treatment will cause the end to break off the male side well there is one more if you have them on your hoses if not un connect and re connect they will hang when un connected after long periods of time and leak ! But the way we come about using them was a old fellow that my dad knew years ago when I was a kid like 5 years old in the 70s will say trade with him and he had used those type and we stuck with them now the compressor was so old there was no ground on the plug end it had tires that were like a go cart you had to put air in them there was no guard on the belt and I remember my dad telling me that this old fellow was one of the first person he knew as a kid growing up that had an air compressor be fore TVs came out and got big dad was born before ww2 I beleve some of the Lincoln quick connectors we use today were from that period in time I’m not for sure which one quick connect fitting came out first but to me the most reliable ones and dependability ones are Lincoln and they are a little pricey a little hard to find and if you want all your motor head friends to look at you like your from another planet this is it because I’ve had so manny look at them and say I’ve never seen that kind be for and follow up with I bet those leak a lot and when I tell them not in over 70 years I don’t think and I’ve worked with them for 30 years my self and have over 20 differant air tools and do every thing from paint, tires and wheels , mechanic work to plasma cutting air arc air die grinding exhaust with a air hammer, and also an air stapler nail guns for wood working and upholstery I’m constantly changeing tools probably way more now than the end ever been in there whole life I have around10 female couplers that I’d say I bought 4 new and remember when dad got all this phematic stuff there were 6 female and there the type you can take apart the ones I purchased you can’t take them apart like the original ones hope this is will inflight every one !
Frank
Newer 1/4″ non high flow couplers of the push to connect variety have a very clean internal flow path virtually identical to the high flow versions.
I designed a plug I call the Stedlin Full Flow plug to fit these couplers and significantly
increase the flow performance.
I recently tested a number of them at 50 CFM and there was virtually no difference in flow/pressure drop.
In my opinion this is a better design than the Euro plug because it is 100 percent compatible with the most common plugs already in use. It is also much easier to connect/disconnect.
David Passwaiter
I have had several quick connects over the years that would leak somewhat not knowing that they were different makes even though they were all I/M types.
I started to look up why they were all starting to leak and what to do about it.
What I came across was Prevost quick connect fittings that release the pressure before realeasing the connection.
David Morgan
I can’t thank you enough for this explainer. I bought an air compressor to do light automotive work with an impact gun and the fittings have had me out of my mind! To allow for high flow, I got a 3/8″ hose on a 50′ reel. But I got a 1/2″ feed hose to go to the reel. And until I read your explainer, I think I was about to give up!
Scargod
My favorite quick connector is Dixon DCB21, Brass “Air Chief” Industrial Interchange Quick-Connect Air Hose Fitting. Snap it on and push to disconnect. One handed operation! Amazing and good quality!
The thing is many supposed “I/M” or M male fittings won’t connect unless I put them in the lathe and increase the length of the large diameter area. Pretty frustrating. Some almost latch…
Lately I’m buying the Dixon brand male pieces.
They meet “MIL specification MIL-C-4109F/A-A-59439” which I would think means “I/M” but, at this point, I’m frustrated with Amazon and shoddy details for products.
Some connect and some don’t.
Tim
I realise that this is an old post but it sits high in a Google search which means that it probably gets found and referred to quite often.
Visitors from outside the US are going to be quite confused when they can’t find a plug that looks like one they have as it appears Nitto Kohki are not ranged in the US.
Perhaps you could add that Australian and New Zealand residents especially are probably going to have these Nitto Kohki connectors or, at least, a cheap copy of them.
https://www.nitto-kohki.co.jp/prd/search/syousai?seihincd=CB66034&lang=en&groupcd=C&vf=
Forde Smith
Hi there,
Great article.
I am from Australia and have a compressor with Nitto connectors. Based on my calipers, the coupling plug on the inflater has a 11.68mm (~12mm?) wide male screw/thread (believe it’s BSP). The airflow looks to be 1/2″.
I have bought a new Park Tool inflater (https://www.parktool.com/product/shop-inflator-inf-2 from the US) that has an 1/4″ Industrial M-Style connector with a 16.73mm (~17mm) male thread (NPT?).
I want to connect the new inflater to the compressor air hose female connector plug.
What is the best option? e.g. reducing bush, nitto fitting for the park inflator? How to get the american speaking japanese (or visa versa)?
Stuart
Park Tool’s user instructions (PDF) say that it has a 3/8″ NPT threated port. The port is female, you will need a male-threaded coupler.
Looking online, there are Nitto quick connect couplers with male 3/8″ NPT threads. I’m not sure where you can source them in Australia, but if I can find it on Amazon, you should be able to find it at local or regional air tool suppliers as well.
You will have to match the plug/quick connect style of your coupler.
There are other ways to go about this, but replacing the Park Tools coupler plug might be the simplest and least expensive.
Forde Smith
Hi @Stuart – thanks for the quick reply. You’re up late?
The only listing on Amazon is out of stock. Seems like these items are not common. I can find plastic ones on ebay…maybe they can suffice until I find a steel one?
If you happen to find one, please let me know.
Forde Smith
Just in case it’s of interest… I phoned two major tool suppliers and they said this is highly uncommon combination, at least in Australia (an imperial measure NPT thread on a metric system with BSP thread ) …no one could source the part for me. There’s one part listed on Amazon but it’s out of stock.
Forde
The more I look into it the more standards and conflicts there are between different country’s systems… Very confusing!
I found the reference in the park tools inflator manual to the 3/8’’ threaded port.
When I measure the size of the thread it is around 16.5mm. 3/8 of an inch is roughly 9.5 mm… That is… 3/8 inch seems way too small for the male thread…So what am I misunderstanding here?
Based on there being no Nitto parts in imperial/NPT measurements, I’m thinking I need a reducing bush to translate between NPT and BSP threads.
The existing part on my compressor is this… 20PM nitto adapter https://www.audel.com.au/air-fittings-20pm-nitto-tail-male-1-4/
Bizarrely… While the thread is a metric PM20/13 mm thread in BSP, the airflow measure is still in inches… Go figure!
There seems to be more of a market in NPT to BSP adapters.
Question I have is… What is the specific part I am looking for? Based on your earlier post / the park manual it would be 3/8 Male NPT to 20PM/13 mm BSP reducing bush. However this doesn’t seem right because the male NPT thread needed is around a 2/3’’ or 16 mm fitting not 3/8’’.
If you can be bothered…Can you help me clarify the exact part needed?
Stuart
Park Tools’ manual says:
[the shop inflator attachment] will accept any 3/8″ NPT male threaded fitting in the event the coupler plug provided is not compatible with the female coupler on the hose being used.”
NPT stands for National Pipe Thread, a US standard for screw threads on threaded pipe fittings and pipe ends.
3/8″ NPT is a standard size with an actual outside diameter of 0.675″, or 17.145mm. (https://en.wikipedia.org/wiki/National_pipe_thread#Standard_sizes)
My understanding is that NPT sizing refers to the inner diameter of piping.
What about Nitto Kohki Hi Cupla 30PM-NPT ? Amazon US carries it, and if this is compatible, you might be able to find it another Nitto dealer in your area.
Otherwise, a BSP to NPT adapter could work.
If I am understanding everything correctly, for the Nitto 20PM fitting you linked to, you would need a 1/4″ BSP female thread to 3/8″ NPT male thread adapter.
Looking online, other international users report success in using a 3/8″ NPT (male) to 1/4″ BSP (female) adapter.
Emilio Gonzalez
I had to figure out and learn myself. Air lines and fittings can be fairly complicated but not insurmountable. I use Milton. Good solid brand. I found out the hard way that I have to use 3/8” hose for air tools. Why weren’t my Dotcos spinning? Ha
David
Have a new Milwaukee cordless air compressor. Would like to know what “style” they used because no coupler I have will stay locked into the factory installed quick connect.
Called their tech support and all they said was return the unit for another one and that the quick connect was defective.
Tyler
Thanks for the info.
Ray knight
I have a male disconnect that does not match anything I see in your post. Plus the threaded end also male that is screwed into a fomer is smaller diameter than the other power washer disconnects. Connector is also larger diameter and will not start to go in water connector or air. If I could email you I would include pics. Maybe you know what I’m trying to describe.
Stuart
You might want to look at power washer quick connect fittings – this post only discusses air fittings.
Stuart T.
Another belated “thank you” for this article, which I conveniently came across this morning after noticing that my Makita compressor was firing up occasionally (like a couple of times a day.) No obvious leaks but learning more about air fittings is no bad thing. Looking at the fittings I have, most seem to be Milton and AFAIK they’re all the same style.
Like another commenter, I’m still confused, but at least I’m somewhat clearer about what I’m confused about (???) I’ve bookmarked this article for future reference.