Pneumatic Quick Connect Fittings

[Lucid Moments]

Which style is the best?

I am trying to get my shop set up and I have ended up with a mish mash of different styles of quick connectors that frequently do not work together. So I need to pick one and convert everything to that style of fitting. I could just figure out which I have the most couplers for (since they are more expensive than plugs) but thought I would check with the hive mind to see if anyone knows if one type is "better" than any of the others.

As usual all opinions are welcome.

 

[LeeG]

I use Milton “M” on everything. Nothing I have needs super high flow.

 

[HMCFab9]

Milton

 

[theoldwizard1]

Just a DIY guy, but I have had good luck with the HF ones ! At their prices, I can afford to replace the couplers if they leak.

 

[Speed-Racer]

Milton type A is my favorite. Any Milton made in USA coupler is hard to beat for the long term. Order 25-100 fittings and few couplers and be done. Search this site for threads.

 

[ekimneirbo]

They are a little harder to find locally so best to go on line. Locally they are too expensive. What I'm talking about is the "industrial" rather than the "automotive" fittings. Look at the size of the hole going thru your fitting. Its very small. It can affect how your air tools run. It will affect spraying with a High Volume Low Pressure spray gun. The industrial fittings flow over twice as much volume at the same pressure. The number of balls in the receiver of the quick connector say a lot about the quality of the connector. The cheap ones eith 3 balls fail all the time. Get ones with more balls and you seldom have to replace one. Get you some hose from Parker or other major supplier that is "push on". They never fail or leak air. Worth the extra money and you don't have to listen to annoying air leaks. If you are setting up a new air system, its worth the extra money. Buy the cheap stuff and wonder why your air tools are weak and your hoses leak..........

https://toolguyd.com/quick-guide-to-air-line-couplers-plugs/

You can find them on Ebay a lot cheaper and they sell groups of fittings.

 

[Elsinore13]

The Milton brass 715 coupler has long been the standard around automotive shops but they don't last for nothing. Always changing them out. Tried different brands and styles over the years and then found these from Wurth. Not cheap, but they work amazingly well, still simple to operate (yes, there are some locking type aluminum couplers out there that are a pain in the *** to connect and disconnect. Too many features I guess!) and hold up long term. Simply push onto the tool, no need to pull back on the outer ring to connect. To disconnect, pull back on the outer ring and it dumps the pressure. Push the outer ring forward to release the tool. Works great.

https://www.wurthusa.com/Shop-Supplies-and-Safety/Air-Hose-%26-Accessories/Air-Couplers/Safety-%26-Push-Button/Wurth-Safety-Air-Coupler-1-4-Female-Short/p/169992001

 

[DHCrocks]

I like the prevost with the safety button release. its a one handed operation, just press the button, pressure is relieved and then the tool can be removed. It won't shoot off the hose end like the typical coupler. its also easy to insert it doesn't feel like you're fighting the pressure. It has a plastic body so it won't scratch paint as easily as the metal couplers do. They are made specific to the type of fitting, but there are many styles available so just pick your poison.

 

[dnschmidt]

If you intend to use professional level paint spray guns (SATA, Iwata, DeVilbiss) you have to use the high flow (Euro style - in America called Milton V) fittings. The performance difference is substantial without them.

 

[Lucid Moments]

I actually found a fair deal from Home Despot for a kit from Milton. It included 2 female couplers, 2 male couplers, 4 female plugs and 6 male plugs. All for $12.86. I just ordered four of them and am going to replace every fitting in the shop.

They are all 1/4" fittings, but I don't do any painting or blasting either one so I don't need particularly high flow.

 

[noid]

I like the prevost with the safety button release. its a one handed operation, just press the button, pressure is relieved and then the tool can be removed. It won't shoot off the hose end like the typical coupler. its also easy to insert it doesn't feel like you're fighting the pressure. It has a plastic body so it won't scratch paint as easily as the metal couplers do. They are made specific to the type of fitting, but there are many styles available so just pick your poison.

+1


http://rtstools.com/deciphering-air-fittings-and-coupler-standards/

I run the prevost in the ESC 07 (euro high flow) standard, but if I had to redo it all, I would run ISC 08 (Industrial) or USC 08 (Automotive fittings/Truflate) fittings.

 

[seber]

Save yourself a lot of frustration and just buy Industrial Interchange. It is industry standard and will always be easily available. It also has higher flow and lower cost than all those proprietary standard. Get a name brand like Parker and forget about failures and leaks. I believe the Milton-M is the same but I could be wrong. Industrial Interchange is used by all production companies because it works. You can also get it with push to lock. No messing around with retracting the sleeve to insert the male end. ARO is also fine but not as popular and will be mor difficult to source when you only need one or two.

 

[sberry]

Ya,,, like 4# loss on a 3/4 gun,,, 2 something on a 1/2. Not anything that cant be compensated for a pinch especially if a guy has 2 stage,,, also almost means nothing to painting or even sandblasting.
Sandblast is usually not more than the output of the comp pump. Down around 15/18 cfm even a cheap fitting isn't losing much effective work.

 

[dnschmidt]

Guys, it's not that tough. JUST LOOK AT THE HOLE IN THE END OF THE ******! If you can't see that the Euro style (Milton V) have a much bigger hole than the Milton M (Industrial) get an appointment with your eye doctor. Bigger hole = More flow. Some things in life aren't that complicated.

 

[kythri]

Save yourself a lot of frustration and just buy Industrial Interchange. It is industry standard and will always be easily available. It also has higher flow and lower cost than all those proprietary standard. Get a name brand like Parker and forget about failures and leaks. I believe the Milton-M is the same but I could be wrong. Industrial Interchange is used by all production companies because it works. You can also get it with push to lock. No messing around with retracting the sleeve to insert the male end. ARO is also fine but not as popular and will be mor difficult to source when you only need one or two.

Industrial Interchange/Milton M is like 40 CFM max.

Milton V are 74 CFM max.

M: https://www.miltonindustries.com/couplers-and-plugs/m-style/1-4-mnpt-m-style-plug.html

V: https://www.miltonindustries.com/couplers-and-plugs/v-style/hi-flo-v-style-1-4-mnpt-steel-plug.html

Here's a thread from GJ; second post from Schurkey has some photos, with the second photo clearly showing the wider orifice of the V compared to the M:

https://www.garagejournal.com/forum/showthread.php?t=347176

Milton V couplers are push to lock. Milton V are backwards compatible with M and A.

I can't identify a single reason that they're not superior to M in any way.

They're super-cheap, too. If you shop around, you can find retailers selling the plugs for less than a buck in both brass and steel, or, their "ColorFit" stuff is color-anodized steel for cheap on Amazon - I'm seeing a box of 20 purple plugs for $17.29 Prime.

I think I'm going to have to re-fit my steel/brass V stuff with the purple stuffs, and use my former stuff to upgrade my dad's shop.

 

[Laminar]

Prevost M style plugs have a 7/32" bore compared to 3/16 for common M style plugs.
This reduces the pressure drop noticeably at flow rates approaching 30 SCFM which is about as high as you're likely to need using 3/8" ID hoses.
The pressure drop of a Milton V and high flow plug is about 4 to 5 PSI at 30 SCFM.
It is 10 PSI with the Prevost M style plug. The very large bore in the high flow plugs doesn't reduce the pressure drop much compared to standard plugs when used with a Milton V or equivalent.

 

[1foxracing]

M on the left, V on the right.

 

[kythri]

V, M, T and L (credit: Schurkey, from https://www.garagejournal.com/forum/showthread.php?t=347176):

 

[Laminar]

There is a significant variation in flow capacity of M style couplers.
I didn't know this until recently.
For example:
A standard Milton M style and similar no name couplers have a pressure drop of over 25 PSI at 30 SCFM using a standard M style plug.
A Foster M style coupler and plug has a pressure drop of 10 PSI at 30 SCFM.
This is very significant.

This would be more than adequate for most people using 3/8" ID hoses and 1/4" NPT fittings.

One of the problems with converting to the Euro high flow plug standard is that you need to change out all your plugs to that standard. If you don't you will experience more leaks.

It seems most people are under the impression that that the large bore in the plug increases the flow substantially. It does but only at flow rates beyond the capacity of 3/8" hoses or possibly using tools at pressures well beyond their rated pressure.

 

[Laminar]

For what it's worth.
The difference in flow rate between a Milton V with high flow plugs and a V with M style plugs is at best 16 percent.

The most restrictive 1/4" air coupler i am aware of is the common type introduced by Milton in the 1940s and still mass produced to this day.
It has a pressure drop of 25 PSI or more at 30 SCFM. (Equivalent to a air cutoff tool at max load.)

There are numerous M style couplers on the market that have much higher flow capacity.

I have a lot of high flow couplers and I now feel they are a waste of money.
None of them work correctly with the large number of M style plugs I have.
The 16 percent improvement is a absolute maximum and is much less in most cases. Hardly worth it. It's easy to make up the difference by raising the system pressure slightly.

 

[dnschmidt]

We can argue this forever but one thing I can tell you for sure is that if you are using SATA HVLP guns (which are air hogs and consume 17 SCFM) you will absolutely, positively notice a difference between the high flow and the normal M. Every major spray gun manufacturer in the world recommends the use of the Euro style couplers and if you paint you'll immediately notice why.

Also, the idea that the V couplers can be used with the M stubs is total marketing ********. THEY CANNOT, AND DOING SO WILL KILL THE V COUPLER QUICKLY.

 

[noid]

I hate to post the same image twice in the same thread, but people seem to be comparing parent styles versus the actual orifice availability:



All of the above are available in 1/4NPT, but the actual orifice range:

ISC 06 and ISC 08 = M style

ESC 07 = V style

USC 06 and USC 08 = T style

As long as you get a USC 08 (T) or ISC 08 (M), it will flow more than a ESC 07 (V).




The above image is comparing a ISC 06 and USC 06 against a ESC 07. Not a fair comparison.

A V style ranges from 7.2-7.4mm, an "06" is 1/4" and an "08" is 3/8".

 

[Laminar]

It’s easy to sell larger plugs as providing increased performance but not easy to explain improvement caused by better coupler design.

Let’s say you have a 4” 1 HP air cut off tool that consumes 30 CFM at the max recommenced pressure of 90 PSI , a 3/8” 25 foot air hose, and Milton V high flow couplers and plugs on both pressure and tool side.
The expected pressure drop would be 15 for the hose plus 8 for the couplers and plugs for a total pressure drop of 23 PSI.
Set your regulator to 113 PSI while trigger pulled and you’re good.
Now picture the same setup with Foster or equivalent couplers and M style plugs. Expected pressure drop 15 + 10 + 10 = 35 PSI.
Now you need to set your regulator to 125 PSI.
In both cases you get identical performance, just at different source pressures.
Since most air tools require much less flow, it seems obvious to me that the M style is a better choice.
You just need to use higher flow M style couplers.

Substitute Milton M style or equivalent and the pressure drop increases to 65 PSI requiring 155 PSI.

 

[Piros1]

Which style is the best?

I am trying to get my shop set up and I have ended up with a mish mash of different styles of quick connectors that frequently do not work together. So I need to pick one and convert everything to that style of fitting. I could just figure out which I have the most couplers for (since they are more expensive than plugs) but thought I would check with the hive mind to see if anyone knows if one type is "better" than any of the others.

As usual all opinions are welcome.

I use the Tru-Flo and really like them do for, I have only been using them for a few months. The nice thing is they are high flow and you can plug a standard Milton connector into them. Not cheap.

 

[kythri]

As long as you get a USC 08 (T) or ISC 08 (M), it will flow more than a ESC 07 (V).

The above image is comparing a ISC 06 and USC 06 against a ESC 07. Not a fair comparison.

https://mdmetric.com/prod/atp/D3Prevostcoupler.pdf has an explanation of the whole ISC/USC/ESC bits that I didn't know before, and is also the source of the graph posted (with accompanying data).

Really, the 08 flow over the 07 isn't significantly more, whereas the 07 over the 06 is significantly more.

You say comparing the 07 to the 06 isn't fair, but they're both 1/4" body size fittings/couplers. Seems pretty fair to me.

08's are 3/8" body size, so comparing 08 to 07 is really, the unfair comparison, but ultimately, when the 07 flows at 82.20 SCFM compared to the 06 at 37.70 SCFM (a 44.50 SCFM increase), the 6.50 SCFM increase by jumping to the 08 (88.70 SCFM, requiring a larger hose with a larger fitting/coupler) is negligible.

 

[sberry]

37,, 35 no big deal. This would make a difference in a 3/4 air gun. when we drop to a 1/2 less than 80% the load. Even a good cutoff is 2/3 hp at best so we are using the losses based on hypothetical WOT and in the case of a rotary like a cut off does the operator want it to scream like an eagle or bog and be able to throttle. Makes loss irrelevant. Big fittings and old rubber hose really make it fly though where a guy could probably roll a 7/16 ball bearing down the old hose.

 

[sberry]

So,,, with a standard fitting with cap of 35 and running at 25 the easiest way to reduce significant loss is shorten the hose, 2/3# a foot or so 3/8. Add an improved connector a couple more # improvement.
There is nothing wrong with better stuff especially if its convenient and easy especially if it interchanges. Put a better coupler on your 1/2 air gun. Use as few as possible which means only at the user end of the hose vs 2 in a row by adding another at a hydrant.
I have one on this utility reel. I have my normal user connector,, M on the end for the tool but happened to use an old auto style from the hose to the pipe as a disconnect when I install it. I got 40 ft of 1/2 at 130#m thru 2 connectors, a swivel 50 ft of reel and got 120 # running at a 6 inch DA I gotta turn down. There is no point in improvement as it works better than it needs too.

 

[noid]

https://mdmetric.com/prod/atp/D3Prevostcoupler.pdf has an explanation of the whole ISC/USC/ESC bits that I didn't know before, and is also the source of the graph posted (with accompanying data).

Really, the 08 flow over the 07 isn't significantly more, whereas the 07 over the 06 is significantly more.

You say comparing the 07 to the 06 isn't fair, but they're both 1/4" body size fittings/couplers. Seems pretty fair to me.

08's are 3/8" body size, so comparing 08 to 07 is really, the unfair comparison, but ultimately, when the 07 flows at 82.20 SCFM compared to the 06 at 37.70 SCFM (a 44.50 SCFM increase), the 6.50 SCFM increase by jumping to the 08 (88.70 SCFM, requiring a larger hose with a larger fitting/coupler) is negligible.

A 08 doesn't require a larger hose or fitting, they come in 1/4 NPT the same way a 06 or an 07 does.

The 07 is an oddball, thats why in the PDF you sent, it is both considered a 1/4 and a 3/8 body, depending on which quick coupler you want (safety coupler is 3/8 body size, regular push button is 1/4 body size).

I agree its not a huge difference between 07 and 08, im running 07 right now on my stuff; if I had to do it over again I would do 08 since its the same cost, and since im using safety couplers, it would come out to all the same body size.

 

[sberry]

A 5 hp comp makes 20CFM. 1/2 the chart max capacity of the fitting for sandblasting any amount of time. Same for losses down the hose at that rate for blast, you can run 3/4 but it wont help get much more work done. Cheaper the compressor the more efficiency of delivery is a concern, cant simply turn it up a little.

 

[sberry]

I use M. It was back in the day before they even thought about "hi efficiency" fittings and they just used a little bigger. I don't know all the math but its a 74 cfm fitting. Its that with 1/4 threads or 1/2 and comes in all 3 sizes. Its a little bigger but can use it for everything and 1/2 hoses.

 

[kythri]

A 08 doesn't require a larger hose or fitting, they come in 1/4 NPT the same way a 06 or an 07 does.

Can you provide reference to that? It looks like 06 is specifically 1/4" and 08 is specifically 3/8".

 

[noid]

Can you provide reference to that? It looks like 06 is specifically 1/4" and 08 is specifically 3/8".

Yeah, look at page 18, part number ISC 081 201, its a 3/8 body in a 1/4 NPT thread.

Same goes for USC 081 201, URC 081 201, and IRC 081 201.

 

[Laminar]

Let's face it.
The unspoken truth is that the main advantage of 1/4" NPT high flow couplers is that they allow the user to run the air tool at well over the rated pressure.

My advice is to stay away from the old style couplers like the standard Milton M style as they are highly restrictive to air flow.