O-Rings 101, Understand the seal-eology

[Schwob]

I created this illustration with Paint: I hope it helps.

View attachment 467466​

Definitely much purtier than my chicken scratch sketch...

 

[The Chairman]

I just found this from www.CarolinaSeal.com . It's awesome and I've seen many of these failures over the years...

 

[emoreira]

Any one has the size of the o-ring that´s inside the power Inflator quick disconnect end of the LP Hose ?

 

[The Chairman]

It should be a 112, if I remember right. You might need some super glue to get that one back together, though.

 

[emoreira]

It should be a 112, if I remember right. You might need some super glue to get that one back together, though.

Thanks. Too much work I did to show which o-ring I was needing !!!
But I didn't notice that the o-ring comes with the new hose I had to buy after cutting mine just to show you which one I was needing.

 

[mrfixitchapman]

Here are a couple of Parco o-ring size charts. First, the web page -

O-ring Size Chart | Parco Inc

Here is a PDF version -

http://www.parcoinc.com/pdfs/O-ring-Size-Chart.pdf

Note that the size chart includes 'metric size equivalent' but this is not the actual metric size chart. I have found that most designers prefer to use o-ring sizes that are SAE sizes that 'overlap' with metric size dimensions. Good thing that o-rings are flexible.

DC

 

[herman]

It should be a 112, if I remember right. You might need some super glue to get that one back together, though.

I am pretty sure that is a 010-70, not a 112. A 112 has a ID of 1/2 inch and a thickness of 3/32 inch (.103).

 

[The Chairman]

"@herman: She can actually measure the OD and let us know. It's really hard to tell from a pic that's displaying differently depending on the screen. To clarify, "010-70" is an 010 size with a 70 durometer. While not the standardized nomenclature, and I haven't been using that either, it gives us a clear idea of the o-ring needed. Standard nomenclature puts aa "AS-568" immediately in front of the size, such as AS-568010. I have only seen that used in government literature. Use whatever works for you.

Fun fact: all Scuba regulators, even those from overseas, use National Pipe straight threads for the port plugs. Most the pipes in your house have the older tapered threads. How do you know? If it has an o-ring, it's a straight pipe thread. If it's being sealed with teflon tape or pipe dope, it's tapered and very rare nowadays in Scuba. The common sizes (as I remember them)

1/4"x 18 NPS
3/8"x 18 NPS

US tanks (Non-US tanks can be different)
3/4"x 14 NPS
7/8"x 14 NF (Not a pipe thread)

DIN
5/8"x 14 BSP parrallel (Different thread from NPS)

 

[Johnoly]

I'd love to see instructions about how the tank handlers " Pop " a tank O-ring out using a loose yoke 1st stage and a blast of air from the valve. I've seen the guys in Coz do it all the time, but it happens so fast. I usually have to take several minutes to dig it out of an AL80, but they " pop " it out in 5 seconds. Then put a new one in and seat it up.

 

[The Chairman]

I'd love to see instructions about how the tank handlers " Pop " a tank O-ring out using a loose yoke 1st stage and a blast of air from the valve. I've seen the guys in Coz do it all the time, but it happens so fast. I usually have to take several minutes to dig it out of an AL80, but they " pop " it out in 5 seconds. Then put a new one in and seat it up.

I've never seen that, but it sounds straightforward enough. I'll have to go experiment this morning. They're just using air pressure to pop that o-ring out which is brilliant. I bet they just have the reg touch the o-ring. It helps if you change them often, too.