Is 8mm tube equivalent to 5/16" tube?

[kwindham]

I'm trying to replace a tube which has some vibration damage in my k14 Bauer compressor, and I'm beginning to educate myself about all the strange fittings and tube sizes. A tube which I had originally misidentified as 5/16" is supposedly 8mm tube with VOSS hydraulic compression fittings. However when look for a replacement, I'm finding that 8mm stainless tubing is nothing short of ridiculously expensive ($130 for 6 feet of 8mm, versus $30 for 6 ft of 5/16).

Given a published manufacturing tolerance of +/- 0.1mm, this puts an 8mm tube between 0.3189" & 0.3110". 0.3125" (5/16) seems to fit comfortably within these limits. Can anybody see any faults in my logic? 5/16 tube is sooo much cheaper. Seems like the best scam ever to sell the same tube for almost 4x more.

 

[Wookie]

No, they aren't the same. If you have no liability exposure, go ahead and use it. If this is in your dive shop, don't. $130 is nothing in the grand scheme of things.

 

[azjohnnyo]

It might be cheaper to order 8mm tubing from Europe...even with shipping it should b a LOT cheaper than $130!!!!! As for diameters, 8mm is .31496 giving a grand total of .00246 or .00123 difference per side compared to 5/16 (.3125"). I'm guessing that they don't hold that tight a tolerance on tubing. There are a few points where metric and imperial come VERY close and this happens to be one of them! Just my 2¢ and YMMV!




JohnnyO
------------
"What if the Hokey Pokey IS what it's all about?"

 

[gcarter]

I don't know exactly what the specs are you need - but McMaster-Carr has stainless 8mm for 74.11 for 2M, Metric Type 316 SS Seamless Tubing 8 mm OD, 6 mm ID, 1 mm Wall, 2 Meter Length

McMaster-Carr

Browse the site and maybe you will find what you need at a reasonable price.

 

[frogman62]

McMaster-Carr is a good source for lots of things - however if you look at the difference between 8.000MM and 5/16 (.3125) you can hardly see the difference .0025 - any compression or flared fitting is going to take up the difference
Jim Shelden

 

[Zodiacdiverdave]

McMaster-Carr is a good source for lots of things - however if you look at the difference between 8.000MM and 5/16 (.3125) you can hardly see the difference .0025 - any compression or flared fitting is going to take up the difference
Jim Shelden

Frogman is correct. You can sub it for 8mm, I have done it many times but don't try it with the 1/4 and 6mm it is not the same.
ZDD