Hot Rod Forum : Hotrodders Bulletin Board - Reply to Topic -- Hot Rod Forum

Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Garage - Tools> air couplers / fittings - whats it all mean?
User Name
lost password?   |   register now

Thread: air couplers / fittings - whats it all mean? Reply to Thread
Send Trackbacks to (Separate multiple URLs with spaces) :

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Please select your insurance company (Optional)


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Additional Options
Miscellaneous Options

Topic Review (Newest First)
10-11-2011 11:07 AM
66GMC 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.


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"
10-11-2011 10:12 AM
S10xGN Ruh-ro, somebody didn't read the guidlines.

01-19-2011 09:28 AM
atariijake thanks for the info!
01-18-2011 09:15 AM
S10xGN 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.

01-18-2011 08:00 AM
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:

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.

06-18-2007 11:53 AM
jcclark 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.
06-16-2007 08:18 PM
mikeweb 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
Style:3/8" True-Flate Automotive 6-ball
Inlet Size:1/4" Inlet Size
Inlet Type:Female Inlet
Quick Connect:No

06-14-2007 04:51 AM
mikeweb I dont let anyone use my tools, plus I have pretty much all the air tools one person would need

HVLP 1/4" are a good idea, to bad they are smaller then 3/8"
06-09-2007 04:52 PM
SteveU 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?
06-08-2007 06:24 PM
Originally Posted by SteveU
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)

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

Type G: Amflo CP7 (True-flate) = 0.295
06-04-2007 06:28 AM
jcclark 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.
06-03-2007 05:41 PM
SteveU 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?
06-03-2007 08:17 AM
mikeweb Good article (halfway down the page) on air fittings/couplers

I ended up picking these up from NAPA

US Item numbers start with NTH, Canada starts with ULT

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

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

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

06-02-2007 09:26 PM
pepi 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
06-02-2007 03:48 PM
SteveU 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
This thread has more than 15 replies. Click here to review the whole thread.

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

All times are GMT -6. The time now is 01:45 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999 - 2012. All Rights Reserved.