DIY reg servicing

[ams511]

I tend to have bad luck at dive shops, most try to sell me new regs telling me that there is new and better now. I find that funny because most of the regulator techs on here and TDS prefer the older models. I did order the oxyhacker book on reg repair and I do have the scuba tools book. My first project will be a Sherwood maximus I bought off of ebay cheap. and the next will be my Beuchats. I have already found a parts source for both. I also have two G-500's that I bought off of ebay that I would like to take a crack at but the parts are difficult to find and then I have noticed that there are upgrade kits and such. I may just bite the bullet and have them professionally serviced.

 

[halocline]

I also have two G-500's that I bought off of ebay that I would like to take a crack at but the parts are difficult to find and then I have noticed that there are upgrade kits and such. I may just bite the bullet and have them professionally serviced.

What parts do you need? The G500 uses the same kit as the G250/S600, it's one of the more common rebuild kits available.

I'm kind of looking for a G500, so if you want to unload one (2nd stage only) send me a PM.

 

[Zung]

...Purchase only from vendors who sell lubricants supplied directly from the factory in carefully selected and tested packaging.

Thanks for the warning David, I'll get your stuff in the factory original package when the time comes.

Until then, I'd very much like to hear your comments regarding the impact of lubricant on the intermediate pressure of a reg. Quoting from Scubapro's Engineering Bulletin:

EB #242: "Both 1st stages should be lubricated with CHRISTO-LUBE * lubricant versus the standard silicone which has been used in the past. If silicone grease is used, you will find in general, that the intermediate pressure range will be higher than what we recommend."

EB #248: "The MK10plus and MK20 1st stages are assembled using Christo-Lube® lubricant, p/n 41-047-000. Your choice of lubricant will affect the intermediate pressure. If standard silicone grease is used, the intermediate pressure could increase by as much as 20 psi. SCUBAPRO recommends using Christo-Lube for these two first stages."

The resident gurus don't buy into that, and I'm just curious.

 

[Texfrazer]

Just don't get it mixed up with the K-Y jelly. That stuff will ruin a regulator.

I really don't (or do I???) want to know how you know this.....

 

[TRIBOLUBE71]

AMS511,
APEX is testing Tribolube® 71 for a possible switch. Point of fact mcg 129 was the grease they used when the PowerPoint was done, but not anymore. Fresh from the box it isn't C-lube.
Now to your mixing issue- mcg129 is a PFPE (perfluoropolyether oil) thickened with PTFE (Polytetrafluoroethylene) and includes a fluorinated corrosion inhibitor. The temperature range of this grease is -40 to 300 deg F (per their data sheet) mcg111 should of been recommended as a dynamic lubricant with a range of -100°F to 450°F (per their data sheet). These markers are achievable if you can keep the oil in the grease. When you service your regulators what does their grease look like? A majority says; cookie dough, much thicker, a white scale or crust is present. Why do you think this occurs? It is a loss of oil from the grease structure leaving the thickener behind as a residue. The choice of PFPE oil (linear or branched) and the size, grade, and the manufacturing method of the PTFE are critical to the behavioral characteristics and performance later as grease. PFPE grease was selected for use in EANx/ Nitrox, mixed gas, Tri-mix, and 30 to 100% oxygen concentrations. Here is a partial list of qualifications; Thermal Stability, Oxidative Stability, Non-Flammability, Chemical Resistance, Resistance to Weathering in oxidizers, fuel sources, acids, and organic solvents.
Dow Corning 111 is the most popular version, and I think this is the one you’re talking about. Silicone grease has been the bane of several industries. If miss-handled it can cause serious problems. Try taking it into an automotive plant where they prep pre-coat and paint car bodies. Poly dimethyl siloxane (silicone) was noted for its migrating nature. When rendered air-borne silicone will move without effort and settle everywhere you do not want it to be. The term “fish-eye” in automotive painting that still elicits negative reactions.
That was automotive and paint, a few spots on your hood don’t compare to what poly dimethyl siloxane will do in the presence of a pressurized supply of oxygen. There is no other way to describe the exothermic reaction it becomes the catalyst for an explosion. Oxygen fires are best to avoid, when you are dependent on it for BREATHABLE air. So that is why no mixing of the two greases. You could contaminate the oxygen grease with silicone grease, put that mix in a CCR set-up with 100% oxygen without knowing you did. There is normally only one time that a diver has the ability to make this type of mistake.
I hope this is helpful, and if there is still some question just ask and I will be happy to help.

When I look at the Apeks PowerPoint presentation they recommend not mixing different lubricants. They say use one or the other (either christo or Dow) but do not mix them. They do not elaborate as to the reason.

You may be right. The powerpoint demo looks rather old so I doubt tribolube was on the market when it was made.

Tribolube has been manufactured since 1973, just not commonplace in the scuba industry. The NAVY divers have used Tribolube 16 and 19 for a long time.

That's undoubtedly because they're talking about two different kinds of grease, silicone and PTFE. Christolube and Tribolube are both PTFE grease, is that correct, David?

Matt,

You are correct, both contain PTFE thickener. Generally the Oxygen greases are called PFPE greases for the oil that they contain.