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air couplers / fittings - whats it all mean?

103K views 18 replies 7 participants last post by  66GMC 
#1 · (Edited)
I always wondered why there were a ton of diff types of air couplers around. Could someone please explain what the diff is between these? and/or provide an informational link?

Style: Automotive vs Industrial Interchange

Type: B, C, E, M, P, ect....

Also, is there any recommendation on which style and type of connector to get?

Is it wise to get a 1/4" HVLP fitting or a regular 3/8" as im unsure to which one gets more airflow. Im looking to use it for my impact gun, cutoff wheel, ect..
 
#2 ·
Get 1/4" type V HVLP fittings & connectors, they have a much larger hole which allows more airflow so your tools will make more power than with the smaller type A or M that most people use. The advantage of type V couplers is that you can use tools with type A & type M fittings along with the type V kind of a universal reciever however the reverse is not true, type V fittings WILL NOT work in type A or type M couplers. I have several cheap air tools which were purchased as part of a kit, I can definitly tell a difference with the larger fitting. The 1/4" size will screw right into your tools so no adapter is needed :thumbup:
 
#4 ·
jcclark said:
The 3/8" ones from Home Depot will fit a std air hose and
air tool too. this kit is $10.00
They have helped all my air tools do better. :thumbup:


Here's how they look compared to std 1/4" ones.
OK I can see the difference in the coupler size ,,,,,,, But, in order to use the 3/8 on the tool itself you have to use a 3/8 to 1/4 adapter in order to attach the plug ... so where is the advantage you are still at 1/4 inlet on the tool? If all the tools and paint guns have 1/4 in inlets a bigger coupler, seems to me to gain nothing.
1/4in. Hi-Flo HVLP Brass Coupler how about this one for instance mfg. is Amflo..
So if you can esplane what the advantage is for the 3/8 plug and coupler. I sure would like to be educated, I am in the process of changing out some couplers and plugs , but have come to the conclusion that the 1/4 Hi-Flo HVLP should do just fine and I would not have to put up with 15 pounds of 3/8 fittings and adapters hanging off the back of the tool. A 1/4 hi flo hvlp does have a bigger hole then the standard HF, milton and Home depot 1/4 types... And one more curve ball, what about the Automotive couplers and plugs whats that all about?... I am all ears or eyes as the case maybe, let it rip..... greg
 
#5 ·
Not sure you are gaining all that much by going 3/8" over the 1/4" HVLP fittings which will screw right into tools without any adapters. Without buying the fitting you show & bringing it home to compare/mic the opening it looks close to what I am running. The type V HVLP fitting is rated for 74 CFM flow which is way more than any of the tools I have use, something like a 1" impact would probably need a larger fitting though. Do they make 3/8" hose with 3/8" fittings? All I have been able to find locally has 1/4" fittings :confused:
 
#6 ·
Well I went on a mission today and this is what I have learned, what the picture does not show about the 3/8 fitting is that they screw right into the air tool, the same as the 1/4 NO adapter needed. I miss spoke in the earlier post and am passing along the following information. The 3/8 fitting and the 1/4 fitting fit the air tools and paint guns just fine. The 3/8 coupler and plug are bigger in mass and require more effort when changing from one tool to the next. Now as to the difference in power I think at this time that there is some benefit, noticed it with the cut off tool, seemed to have a diminished tendency to stall. I am using a 3/8 hose and wonder if a 1/2 hose would produce even more power at the tool. Keeping in mind that the compressor will more then likely cycle more. As to the HFLV fittings I would like to check the hole size of one of those to see if there is a difference between the 3/8 and it. If they are the same then the advantage would for the HFLV because of the fitting size and mass, that would be the only advantage the flow rate would be the same. Another nice thing about the 3/8, most folks will not be able to borrow your tool, it wont fit there couplers. Now I will go have some coffee with my humble pie
 
#7 · (Edited)
Good article (halfway down the page) on air fittings/couplers

http://www.homemetalshopclub.org/news/aug03/aug03.html



I ended up picking these up from NAPA

US Item numbers start with NTH, Canada starts with ULT

Item#: NTH90686
Attributes:
Type:G
Style:3/8" True-Flate Automotive 6-ball
Inlet Size:1/4" Inlet Size
Inlet Type:Female Inlet
Quick Connect:No




Item#: NTH90685
Attributes:
Type:G
Style:3/8" True-Flate Automotive
Inlet Size:1/4"
Inlet Type:Male Inlet




Item#: NTH90687
Attributes:
Type:G
Style:3/8" True-Flate Automotive
Inlet Size:1/4"
Inlet Type:Female Inlet

 
#9 ·
The biggest restriction of the 1/4" fitting is the opening in the coupler,
not the hole you see in the connection side of the fitting.
That's where the 3/8" ones help so much more, they don't choke it down
near as much. Look at the pictures and you can see it.
The 1/4" couplers have a much smaller hole inside the coupler.
It doesn't take much increase in diameter to double the air flow.

I did a test with a pressure gage at my gun with trying both sizes
of fittings and the pressure drop was 5 lbs with the 3/8" and
20 lbs with the 1/4" ones. They do make a huge difference.
I did the same test with a 1/2" hose verses a 3/8" one and didn't
notice any difference.
But that could change with a higher CFM consuming tool than mine.
But at 10 CFM I couldn't measure a difference. :pimp:
 
#10 · (Edited)
SteveU said:
Just mic'd some 1/4" male fittings, Type M no name .187 hole, Type M Milton .202, Type V Milton .275. This is the size of the opening at the smallest point so airflow will vary accordingly. Does anyone have the size of the 3/8" fittings?

I just measured my fittings using a digital caliper (inside jaws)

1/4"
Type M: Milton 727 = 0.197
Type I/M: Campbell Hausfeld = 0.191
Type M: No Name = 0.188

3/8"
Type G: Amflo CP7 (True-flate) = 0.295
 
#11 ·
Either the 3/8" or 1/4" HVLP will be a BIG improvement over the standard fittings that most everyone uses. The primary advantage I can see of the 1/4" HVLP over the 3/8" is that my buddy can bring his air tools with type A or M fittings over & they will hook right up into my connectors where with the 3/8" connectors we would have to change the fitting on his tool for it to work then switch back before he leaves. Unless, if you could convince your friends of the advantages & get them to change to the same type fitting then the advantage would go to the 3/8". Found 3/8" HVLP fittings in the Northern master catalog, wonder if anyone here uses them?
 
#13 ·
Well, I just used my impact gun for the first time after changing to 3/8", it felt twice as powerful.

I should of put these on from day 1, my only complaint is that its a pain in the *** to change tools while the hose is pressurized. No longer can you do it with a light pull, you really have to get into it.

Im not sure why although it does state NO under "Quick Connect". Maybe I should put some grease on the ballbearings?

Any idea's guys?


Item#: NTH90686
Attributes:
Type:G
Style:3/8" True-Flate Automotive 6-ball
Inlet Size:1/4" Inlet Size
Inlet Type:Female Inlet
Quick Connect:No

 
#14 ·
I have put a little Vaseline on the male connector.
And you can spray silicone lube on the female.
(Although I wouldn't use those for painting.)
I took a coupling apart once, cleaned and lightly
lubed everything with Vaseline,
That really helped, (they do crud up after awhile.)
But they're still not as easy as the smaller 1/4" connectors. :pimp:
 
#15 ·
Still some air coupler confusion...

Hey guys, sorry for posting to an old thread. I've been trying to figure out the 1/4" type "V" vs 3/8" air coupler issue. I just recently picked up an air compressor and I'm trying to get as much air as possible from the compressor to my tools, especially my paint gun.

I'm very new to all this and just wanted to ask the pros before I sunk some money into it.

I've read that the Milton type "V" fittings are good and more universal, but it's my understanding from reading through this thread and a few others that the 3/8" coupling size is even better.

I went to Northern the other day and they didn't even have a regular air hose with 3/8" NPT ends, only 1/4" ends.

I did find a 25ft rubber hose with 3/8" ends at Grainger though.

Here's the link:
http://www.grainger.com/Grainger/SPEEDAIRE-General-Duty-Multi-Purpose-EPDM-3JT69?Pid=search

This is going to sound like a dumb question, but just to be on the safe side, I do need an air hose with 3/8" ends to use the larger 3/8" fittings right?

And I found on Milton's site where they sell a type "V" fitting in a 3/8" size as well. Would this be worth it?

I have a small compressor so with all the larger style fittings it might be really hard on the compressor, but I'll need to upgrade eventually anyway.

Thanks!
 
#16 ·
All my type "V" connectors are 1/4" NPT (the pipe size is not the bottleneck, the coupling end is), you can't go wrong with either size pipe end. A 3/8" hose is better for long runs than a 1/4" hose. I'd say go with whatever fitting is easier for you to obtain, as the 3/8" hose can be had with either size ends.

Russ
 
#19 · (Edited)
Air couplers and plugs can be very confusing, mostly because of the fact that many different mfr's come up with their own methods of identifying them.



With Milton (to the best of my understanding):
A = Aero
M = Milton (Everyone else refers to these as "Industrial"
T = Truflate
L = Lincoln

I see that Shraeder-Bridgeport has recently come up with a fairly good cross-reference between many of the "common" brands, including NAPA (which is really Shraeder-Bridgeport) Links to both the product catalog itself and the cross-reference charts can be found at the above hyperlink.

BTW, MOST of this product line is now under line-code NTH in Canada as well.

I also believe the terms "quick-coupler", "automatic coupler", and "push-connect coupler" to be the same thing.

PS.

Milton makes a "3-in-one" "A-M-T" coupler (#745 / 746) that accepts most common types, including the long "Lincoln" style ... so it's really a "4-in-one" :thumbup:
 
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