Changing the tank thread

[pisauron]

Because those Chinese CF cylinders are nearly impossible to get hydrostatic tested and have a limited life span, takes a unique valve with a specific tiny Oring too.

Sure they are super light weight, but if it's just to sit under a workshop bench what's the point? A cheap old low pressure steel tank lasts for decades and you can find one used for cheap.

Why do you have a problem getting them hydro tested?

My work bench is actually in my truck, a lightweight tank will fit me well.

And sadly we have no cheap tanks where i'm at.

 

[The Chairman]

Why do you have a problem getting them hydro tested?

It depends on whether they're DOT certified to begin with. Many tanks in the US are not.

 

[TravisD]

Note that the OP appears to be in Israel, so doubtful that US standards apply?

 

[pisauron]

It depends on whether they're DOT certified to begin with. Many tanks in the US are not.

That's a problem we don't have here

 

[The Chairman]

Back to the OP. I've rethreaded DIN threads because the tank was dropped. I do own the 3/4 thread tap, and while I've used it to clean up corrosion on threads, and make jigs with it, I would never try to re-thread a tank neck, especially not to attempt to resize it. My life and appendages are worth more than a cheap tank.

 

[The Chairman]

That's a problem we don't have here

I own my own compressor, so I don't worry much about it either.

 

[pisauron]

Back to the OP. I've rethreaded DIN threads because the tank was dropped. I do own the 3/4 thread tap, and while I've used it to clean up corrosion on threads, and make jigs with it, I would never try to re-thread a tank neck, especially not to attempt to resize it. My life and appendages are worth more than a cheap tank.

The scary stuff is that most likely somebody rethreaded this one, and from 18mm to 24mm which is A LOT. Then somehow it ended in our shop scraps.

 

[The Chairman]

Then somehow it ended in our shop scraps.

Time to fire up the ol' foundry! They're pretty cheap now and then you can make aluminum bars to machine other things out of.

 

[rjack321]

Why do you have a problem getting them hydro tested?

My work bench is actually in my truck, a lightweight tank will fit me well.

And sadly we have no cheap tanks where i'm at.

Will your hydro shop recognize them? They are not built to an approved standard for my country. They still take a unique valve, with potentially non-standard parts, a unique o-ring, and have a 15yr lifespan. Plus no resale value. Filling them to 300 bar is hard on compressors.

An Al40 would be cheaper, easier, use existing scuba valve parts, not have a defined service lifespan, and if you don't want it anymore would have some resale value.

 

[pisauron]

Will your hydro shop recognize them? They are not built to an approved standard for my country. They still take a unique valve, with potentially non-standard parts, a unique o-ring, and have a 15yr lifespan. Plus no resale value. Filling them to 300 bar is hard on compressors.

An Al40 would be cheaper, easier, use existing scuba valve parts, not have a defined service lifespan, and if you don't want it anymore would have some resale value.

I think it will be fine here. They are labeled EN 12245 which should be ok. If they have M18*1.5 thread that's a common scuba valve too.

An Al40 would cost 450$ here.