Scubapro R190/R380/R390 Nylock nut

[NJDiver07866]

Thanks again everyone for your help in the past.
Few questions on the nylock nut on the scubapro 2nd stage.

In the manual it says to disregard and throw out the nut every time you take it off. Is there anything special about this nut? Meaning I have a local shop that caries a bunch of odd shape fasteners. I wanted to pick up a ton of these nuts. My nut *no jokes please* has like a purple nylon looking thread on it.. the one pictured in the kit is white.. so I'm thinking I can just pick up the same type 1/4 nut at a specialty shop?

If the directions say replace every time I will. I would like to know why.. I guess the nylon does not last too long? But just wanted to get your guys thoughts and experiences on this nut. Or should I just stick to the scubapro nuts. I'm pretty sure they just repackage a standard 1/4 nyloc nut, don't want to make any assumptions...

Thanks for your help, I took the 2nd stage apart, with the diagram next to me. Was a bit nail bitting at first, but all kidding aside.. not really that bad. Cleaned it all up and put it back together, adjusted the cracking pressure, measured it with a magnehelic guage and everything is working just great!!

Thank you everyone for your help...

 

[NJDiver07866]

By looking online.. There is a bunch of variations of a 1/4 nyloc nut. Thread size, face size etc..

McMaster-Carr

I think this is them. Just have to figure out the Inch Thread size & the overall length (9/64 or 7/64).

Will post if I find anything more.

Thanks,
Rich

 

[NJDiver07866]

and I'm assuming stainless steel would be the better one instead of the steel w/ zink finish..

 

[DA Aquamaster]

You definitely want stainless steel so that it will not corrode in place.

If you have to re-adjust the nut or remove it, then replace it as they don't hold as well when re-adjusted or reused. The reason is simple enough - if it unscrews the lever falls off and the reg will stop delivering gas. A failure to deliver gas failure is bad news, so a new ny-lock nut is cheap insurance.

 

[redacted]

If it does unscrew, cracking effort will go to hell in a handbasket well before the the nut and lever fall off. I got a supply of nuts from M-C but old habits die slowly. I reuse these nuts and have never had any problem.

 

[cbmech2]

The nyloc nut has the nylon insert that when screwed down helps to hold the nut in place. Although some may choose not to replace it, replacing the nut is cheap insurance against the nut possibly coming loose. It is also designated as an annual replacement part, hence the reason why it is included in the annual service kits for those regulators where it is used. I am with DA in his recommendation to get a stainless nut for a replacement. The last thing you want is to have the nut weld itself to the threads of the poppet.

 

[Packhorse]

Next you will be wanting to buy a sheet of neoprene and a hole punch to make new seats!

Would you really trust your life to a service kit that cost you less than $1 to assemble?

 

[redacted]

Next you will be wanting to buy a sheet of neoprene and a hole punch to make new seats!

Would you really trust your life to a service kit that cost you less than $1 to assemble?

I do about that with no problems. But I use duro 80 viton rather than neoprene. I have been using them for about a year now. I doubt if those 2nd stage kits cost the manufacturer even a dollar. My homemade seats are costing me about a penny each (a $6 sheet will make over 600 seats). The o-rings in those kits should also be only pennies each in quantity. And the lock nut is maybe a nickle. Packaging might double the cost. Yet, the retail price for those kits runs $8 to $15 each, if you can find a retailer who will even sell them. And that is the biggest rub. Most manufacturers want to force you to spend $100 (parts & labor) for what amounts to a couple dollars worth of parts.

 

[NJDiver07866]

Thanks for the help folks. I'm totally with you guys, I'm not trying to save a few bucks. With just getting into DIY and having a set of all new tools from Scubatools I have taken apart the reg and put it back together a 1/2 dozen times or so (i bet it gets old, but now its fun and new). Not looking to go cheap, and will replace the nut every time. Just thought there would be a better way instead of buying a new scuba pro kit for $22 bucks a shot. So if anyone has the exact size so I can get a few dozen of these nuts it would help out greatly.

I'm going to the special nut shop to see if the guy can measure my nuts to get me nice shiny nuts so my rod won't fall off. But if anyone knows the size of my nuts off the top of their head, It would help out to verify that the guy measuring my nuts is right. (OCD rebreather training.. worst thing I fear is putting the wrong sized nut that close to my mouth and having my rod fall off)

I won't go as far as punching out my own seats, but kudos for the creativity!!!

Thanks folks will post back

 

[NJDiver07866]

OK nut measured and confirmed. I ordered it from the McMaster site.
Part #91831A006
1 Pack 18-8 Stainless Steel Nylon-insert Hex Locknut5-40 Thread Size, 1/4" Width, 9/64" Height.

$4.92 for a box of 100.. so ~ 5 cents a nut.

Thanks all for the help...