O-Rings
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I'm very sorry to bring this to you,but IF you don't know the basics,what are you going to do with these O-RINGS ?
If you can't read the specs.
Maybe I am missing something. I can read the specs on the O-ring web site. But I am not able to decipher the Sherwood part numbers to materials (compounds) and durometers.
In the past, I have purchased by the Sherwood part numbers. I didn't need to know the compounds or durometer to do so.
It is not very hard to replace the valve O-ring, when you have the correct Sherwood part number O-Ring for a Sherwood valve. :mooner:
What I am asking here is how to go from (decipher) the Sherwood part number into it's compound and durometer. I realize (or suspect) that the specifications are encoded in their part number based on your response. I just am not familiar with that coding, even if it is very basic.
Packhorse
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I'm very sorry to bring this to you,but IF you don't know the basics,what are you going to do with these O-RINGS ?
If you can't read the specs.
Shame on you 300bar. This is the DIY forum and the posters wants to learn a bit more so are asking questions. What is wrong with that?
I dont know about you but I find it the best way to learn.
Hoosier
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For DIYer, there are three ways to detect an exact duro.
1. Somebody tells you or you get an info from the various sources including a direct inquiry to the manufacture.
2. Compare an actual O-ring with other various O-rings in a different duro. This is the cheapest way, but you need to stock all kinds of popular duro in the popular materials.
3. Get the durometer, but it is very pricey...
I am using 1 and 2.
Most O-ring is EPDM, Viton or Nitrile. Viton is an obvious due to the unique color. So, you will end up with EPDM pretty much instead of a cheapy Nitrile material.
Duro variation is from 70 to 90. Now, you need to play with each duro.
Just my 2 bar.
I'm very sorry to bring this to you,but IF you don't know the basics,what are you going to do with these O-RINGS ?
If you can't read the specs.
Hoosier, thank you. According to 300bar, it's because I'm too dumb to read basic specifications.
So, I guess my question still remains - Does the Sherwood part number contain a code for compound and/or duro?
If I went by Scubakevdm, using the link supplied by Luis H in post #3, I would require Nitrile (Buna-N) 90 duro O-Rings for all HP portions. This is the only compound that duro 90 is available from that source. But, if I go to DiveRite, they have Viton in both 90 and 75 duro. I cannot see any correlation between between the Sherwood part numbers for low pressure and high pressure.
I have read the tutorial on DiveRite that address the Society of Automotive Engineers AS568B Aerospace Standard, but it seems to only contain sizing information within the number. I find no reference to compound or duro within the AS568B numbering scheme.
Would someone please enlighten me on the basics of how to read the spec's? Or, just tell me if/how I can get the compound and duro from the Sherwood part number.
Hello Waterskier,
Wow, you are taking a beating here trying to get a little bit of basic information. Don't let it put you off.
First thing, the numbers you see in your Sherwood Manual may or may not easily cross reference into a standard o-ring size, but that only matters if you are ordering from Sherwood-which is not the case. Chances are the numbers that you see e.g.. G007A are Sherwood's part numbers. Most manufactures, not necessasarily confined to SCUBA) give the o-ring their own designation. But, none of that matters. What does matter is the correct size, material and hardness and a quality o-ring.
Lets start with the size. Use your G010A as example, chances are the correct size is -010, (a typical l/p hose or plug size) but it is best to be sure. So you either have to measure a good o-ring or take one in for comparison. You have already read the information at http://www.diveriteexpress.com/hardware/orings.shtml so I will not attempt to repeat any of that; but rather suggest you go to a hardware store, automotive parts store or anywhere you can find common o-rings and a size chart. If you have an o-ring supplier or hydraulic hose shop near by, go there. For now, we only want cheap o-rings in order to get the correct sizes. After you know the correct sizes for each application you can either buy quality o-rings from one of the sites previously listed or from a decent supplier.
Material...You can not go wrong with FKM (Viton) or EPDM, both are O2 compatible and have great shelf life so no worries about them going bad if you buy a bunch.
Durometer…Duro 70 to 90 will work in any SCUBA application except where you have a high pressure differential such as a piston stem where you should use a duro 90. Just to keep things simple, I always order duro 90, some of my DIY brethren have different view points, but it works for me.
Quality…..Buy genuine Viton or Parker o-rings or buy from a reputable dealer (see Luis's post) and just to be sure, get aviation grade. They only cost a little more, but at least you know there has been some quality control in the manufacturing process.
Color, sorry, o-ring material can not be determined by color. Viton, comes in black, brown and probably a few other colors.
I hope this helps,
couv
Wow, you are taking a beating here trying to get a little bit of basic information. Don't let it put you off.
First thing, the numbers you see in your Sherwood Manual may or may not easily cross reference into a standard o-ring size, but that only matters if you are ordering from Sherwood-which is not the case. Chances are the numbers that you see e.g.. G007A are Sherwood's part numbers. Most manufactures, not necessasarily confined to SCUBA) give the o-ring their own designation. But, none of that matters. What does matter is the correct size, material and hardness and a quality o-ring.
Lets start with the size. Use your G010A as example, chances are the correct size is -010, (a typical l/p hose or plug size) but it is best to be sure. So you either have to measure a good o-ring or take one in for comparison. You have already read the information at http://www.diveriteexpress.com/hardware/orings.shtml so I will not attempt to repeat any of that; but rather suggest you go to a hardware store, automotive parts store or anywhere you can find common o-rings and a size chart. If you have an o-ring supplier or hydraulic hose shop near by, go there. For now, we only want cheap o-rings in order to get the correct sizes. After you know the correct sizes for each application you can either buy quality o-rings from one of the sites previously listed or from a decent supplier.
Material...You can not go wrong with FKM (Viton) or EPDM, both are O2 compatible and have great shelf life so no worries about them going bad if you buy a bunch.
Durometer…Duro 70 to 90 will work in any SCUBA application except where you have a high pressure differential such as a piston stem where you should use a duro 90. Just to keep things simple, I always order duro 90, some of my DIY brethren have different view points, but it works for me.
Quality…..Buy genuine Viton or Parker o-rings or buy from a reputable dealer (see Luis's post) and just to be sure, get aviation grade. They only cost a little more, but at least you know there has been some quality control in the manufacturing process.
Color, sorry, o-ring material can not be determined by color. Viton, comes in black, brown and probably a few other colors.
I hope this helps,
couv
couv,
Thank you very much. I have already confirmed that the number in the Sherwood part number indeed seems to follow the AS568 numbering convention. So I do know the sizes I need.
I read before that I should use Duro 90 for HP locations. I also had previously read that Viton was compound of choice for O2 use (I currently don't expect to be using anything >40% O2 though). The problem came when I tried to use Luis's web site to find the O-Rings. They don't list (or I am missing) anything besides Nitrile (Buna-N) in 90 Duro. The Viton comes only in 75 duro, and EDPM only in 70 duro.
The DiveRite site does have Viton in 90 duro, but not volume sales. I will check around unless someone has a preferred site that sells 90 duro Viton or EDPM O-rings they would be willing to post.
Again, thank you couv.
Thank you very much. I have already confirmed that the number in the Sherwood part number indeed seems to follow the AS568 numbering convention. So I do know the sizes I need.
I read before that I should use Duro 90 for HP locations. I also had previously read that Viton was compound of choice for O2 use (I currently don't expect to be using anything >40% O2 though). The problem came when I tried to use Luis's web site to find the O-Rings. They don't list (or I am missing) anything besides Nitrile (Buna-N) in 90 Duro. The Viton comes only in 75 duro, and EDPM only in 70 duro.
The DiveRite site does have Viton in 90 duro, but not volume sales. I will check around unless someone has a preferred site that sells 90 duro Viton or EDPM O-rings they would be willing to post.
Again, thank you couv.
Hoosier
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The part number might be clue or not. Personally, I don't care that much about their part number because it is named for their own convenience. For example, SP part number doesn't contain any spec. reference.
I measured one by one pretty much.
You're right. Most common duro are 70, 75, and 90.. 80 is rare except a special order. There is a big difference between 70 and 90, but NOT that much between 70 and 80. So, if you compare Sherwood O-ring with 70 and 90, it won't difficult to find out the closest duro. 80 duro is tricky one because you have to find out where the stock one is 80 or not over time.
How?
It doesn't last long and leak eventually. If you are using 70 on the spec-ed 90 duro places, it doesn't last long as well (might last only a couple of months).
Good luck!
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O-rings online has a toll free number, if you like that site, just give them a call.
I like the folks at http://www.oringsusa.com/
Once there click on the BUY ONLINE button
Then in the search window type in: m83248/1 (for Viton duro 75) m83248/2 (for Viton 90)
Then scroll down until you find the size you need and click the BUY NOW button next to it.
Note that buying only one will cost you a lot more per o-ring, so play with the quantity buttons and you will find that (just for instance) for a m83248/2-010 if you buy 70 of them, they are only .10 each and one will cost you .25
couv
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