Air Fitting ID

[4nthony]

The chrome quick connect fitting below came off a vacuum pump with what I think is 1/4" ID hose. I want to route some new hose around my workbench and ordered a barbed brass quick connect fitting from McMaster to make an additional connection. The brass should work for what I want to do, but I'd like to learn more about the chrome fitting.

• They both have a 5/16" tip but the chrome tip length is 3/32" while the brass is 3/16"
• The chrome barbs are 9/32" while the brass barbs are 11/32"
• The chrome fitting has a flat space between the barbs and stop while the brass barbs continue to the stop

Specs for the McMaster fittings

Based on the McMaster chart, would it be considered European or Compact? I went through the filters on McMaster to try and narrow it down, but a 3/32" tip length is not available for either connection. It's also difficult to find the same barb pattern.

I like that the chrome fittings are much smaller than the industrial brass I purchased.

Thoughts?

 

[Chainring]

Interesting you post this, Anthony. The bottom one looks similar to what I'm seeing on a TrailKeg for CO2 connections. The thread is 1/8 BSPP.
https://trailkeg.com/collections/trailkeg-accessories

 

[Crazyraceguy]

The top one, which they call Industrial now a days, used to be called Milton. It was a brand name that somehow got removed and became generic.
That has been what was used in every shop I have ever worked in, from the truck mechanics to the auto body shop and the cabinet shop where I am now.

The one your list calls Tru-flate used to be called "automotive" but I have never seen a shop use them.
The Milton (industrial) has been the standard.

 

[4nthony]

Looks like it's called a "mini coupling". It's quite possible the hose I have is 4mm ID and not 1/4" as I thought.

https://usd.pclairtechnology.com/mini-adaptor-4mm-i-d-hose-tailpiecehttps://usd.pclairtechnology.com/mini-coupling-male-thread-g-1-4

 

[jonnyrocket]

I was just looking in the Parker catalog and found this series of their connectors that apppeara to be close as well. They call it “mini industrial”.

[attachimg=1]
https://ph.parker.com/us/en/series-21-quick-coupling/21sftf10mxnhttps://ph.parker.com/us/en/series-21-quick-coupling

 

[4nthony]

If the "Ultimate Pressure" of a pump is 150 and a fitting can handle applications up to 35 bar, are they still compatible?

Is bar kinda like CFM, in that a stated CFM value is never really achieved in real-world use?

...

 

[tsmi243]

Is bar kinda like CFM, in that a stated CFM value is never really achieved in real-world use?

No, pressure isn't dependent on "ideal conditions" in the same way a flow rating would be- and it's a LOT more straight-forward to regulate, so you'd only get max pressure if you crank the knob on the regulator all the way to 11 (and you DO want a regulator if you're pressurizing anything- don't hook this pump up to a pressure tank and walk away!)

And that would be output pressure- In a vacuum system, the pump can only reach absolute vacuum- which is 1bar negative.  More power doesn't get you any more force than that, no matter how long you run it.  So your vacuum fittings don't need to be any stronger than 1bar. 

I hope I understood your question?

 

[4nthony]

No, pressure isn't dependent on "ideal conditions" in the same way a flow rating would be- and it's a LOT more straight-forward to regulate, so you'd only get max pressure if you crank the knob on the regulator all the way to 11 (and you DO want a regulator if you're pressurizing anything- don't hook this pump up to a pressure tank and walk away!)

And that would be output pressure- In a vacuum system, the pump can only reach absolute vacuum- which is 1bar negative.  More power doesn't get you any more force than that, no matter how long you run it.  So your vacuum fittings don't need to be any stronger than 1bar. 

I hope I understood your question?

I'm not sure I actually understood my question!  [embarassed] [doh]

I was mistakenly thinking the pump would exceed the capability of the fitting, and that bar and mBar were 1:1 equivalents. I just learned that mBar is millibar.

So the 150 mBar the pump produces is only .15 bar. A 35 bar fitting is more than enough.

 

[tsmi243]

I wasn't trying to talk down to ya. [big grin]  Just being thorough, because airflow isn't real intuitive to everybody.  It's hard not to sound condescending sometimes.

Anyway, I'm using the VAC SYS with some of the cheapest fittings you can imagine.  No problems yet. 

 

[4nthony]

I wasn't trying to talk down to ya. [big grin] 

No worries, I didn't think you were.

There's a lot of things beyond just using a tool that I have no idea about. Airflow, phases, cycles...I read some of the posts on here and serious imposter syndrome kicks in.

 

[Kotboros]

The length of the barb and the space between them can make a difference in how securely the hose fits, so it's good you're paying attention to that. In my experience, the chrome fittings are usually made for higher-pressure systems, so the shorter barb length might be designed for a tighter seal in those cases. The brass fitting, being a bit longer, might be better for lower-pressure or more flexible setups, but as long as you're using the right hose size and ensuring a tight fit, you should be good to go.
I’ve used quick couplers from Northern Hydraulics on a similar setup before, and they worked great for adding flexibility to my system.

 

[smorgasbord]

The top one, which they call Industrial now a days, used to be called Milton. It was a brand name that somehow got removed and became generic.
That has been what was used in every shop I have ever worked in, from the truck mechanics to the auto body shop and the cabinet shop where I am now.
The one your list calls Tru-flate used to be called "automotive" but I have never seen a shop use them.
The Milton (industrial) has been the standard.

This thread got bumped, but at any rate I recently swapped out all my female couplers for the Milton brand "V Style" version, which is not only high flow, but is also compatible with most other male plugs. And you don't have to pull a ring backwards to plug in - when you disconnect the ring stays back and then snaps forward when a plug is firmly seated. So, I no longer get the almost inserted but pops out on first use condition.

Be warned, though, the V-style male plugs won't work with most other female connectors, so only use them if you need the high flow for a sprayer or something.

 

[rst]

I've been using standard "Milton" style connectors on vacuum jigs and clamps for 40 years without issues. I've also used push/pull fittings also. For example, so I can make hose from my vac sys easier to puy away.  I also used them to connect to the Virutex clamps I have from before the Festool system became available.