Info needed on some sort of metric sperical inverted flare fitting

[AaronH]

Hi all,

I have a hose off an air compressor that has come into my possesion. The compressor was free and now I know why. It's one of those wheel around portable units, but a bit heavier duty that the ones you find today. It's missing some pieces and to date I haven't found a manufacturer name. Here's my dilema: the approximately 1/4" hose that connects the compressor head to a manifold is rotted. The manifold has a compressor pressure gauge, regulator, regulated pressure gauge, pop-off valve, and a tank output. The fitting on this hose appears to be some sort of metric sperical inverted flare. It's a swivel fitting with female threads. I believe it's a M14 X 1.0 thread. I can confirm later tonight when I take a better look at the male threads. The flare portion I guess you would call male and is definately sperical. I stopped by Tractor Supply today and found a 1/4" NPS to NPT adapter fitting that seems to fit the sperical flare well, but the threads are too small and too coarse. I can change the fitting in the compressor head, but the manifold is white metal/zinc die cast. I could also make a new manifold, but am trying to avoid that much work. Any thoughts as to what this fitting is?

Thanks,
Aaron

 

[hydromech]

I would suggest that the thread is 1/4" BSP.

The only difference between 1/4" BSP and 1/4" NPT is the flank angle on the thread form.

1/4" BSP will screw into a 1/4" NPT hole and vice versa, but it will be a little tight.

I cannot think of any other thread forms that are coned...?

Adrian

 

[AaronH]

I took a closer look at the swivel fitting I have in my hand right now and it's definately finer than BSP. It's either the M14 X 1.0 or possibly something like a 9/16"-26. I'm guessing it's going to be the metric variety.

 

[hydromech]

When you say inverted to you mean the cone is male or female?

The only M14 swivel thread that has a male(inverted) cone is either...

6mm S series compression fitting

or

8mm L series compression fitting

The thread on both of these fittings is M14 X 1.5

If this is the fitting it should have a 22 degree taper/cone...

I really cannot think of another type of metric fitting that has a cone...

 

[kcj]

Aeroquip, Now Eaton, has a small booklet called 'How To Identify Fluid Ports and Connectors'
Document number E-SROV-TS009-E
Youmight find it on the Eaton website, or get from a loacal Aeroquip dealer.

Used to be red, now its blue, is about46 pp, and pocket size. It identifies fro various countries.

DIN7631 has a M14 x 1.5, cone seal, DIN 3902 has same threads, French GAZ, japanese JIS30 degrees, etc.

Assuming its a cheaper homeowen unit, is itmade in China metric?

Can you just take the block off and retap to NPT? I hate NPT wiht a passion, but being able to tap threads in the field with simple tools is it's one saving grace.

good luck.
kcj

 

[AaronH]

Ok, I think I have figured it out. I must say the answer kinda makes me want to hit my head against the wall. I think based on some experimenting at Lowes last night that it turns out the fittings on the compressor are nothing more complicated than 3/8" compression fittings. (btw, anyone know the thread on a 3"8" compression nut?) It makes sense now because copper tubing is pretty common on air compressors.(see head against wall above) What was throwing me off was the hose that I took off the compressor. I believe that someone somewhere along the line replaced the original copper tubing with this rubber hose. From what I could tell, this hose is a sink faucet hose. Not sure what the pressure rating is on those but I am guessing it is directly related to the rupture in the side. The piece inside the female swivel on this hose is definately sperical in shape, whereas the ones today are conical. The sperical piece fits inside the male compression fitting and by my guess just lines up the fitting properly so that it can seal on the end of the fitting via metal to metal contact of a larger diameter shoulder (or perhaps a long lost gasket/O-ring). This old hose is a bit different than the new ones. The old hose has the same style fitting on both ends. Whereas, the new hoses have a much larger fitting on one end. I imagine the fitting on the faucets have changed over the years. At any rate, I'm going to fit some new copper line and see what happens. Thanks for all of your help.

Aaron