Is the SPG O-ring supposed to be replaced during annual inspections?

[Bubbletrubble]

@PhilEllis: Thanks for sharing how your shop does things.

I'm just curious. What durometer and material o-ring do your technicians use on the HP spools? Also, do your technicians clean up the HP hose end that connects to the SPG with an ultrasonic cleaner or vinegar:water bath?

 

[PhilEllis]

@PhilEllis: Thanks for sharing how your shop does things.

I'm just curious. What durometer and material o-ring do your technicians use on the HP spools? Also, do your technicians clean up the HP hose end that connects to the SPG with an ultrasonic cleaner or vinegar:water bath?

On the "rebuild" service, we clean the entire hose....both ends and the inside. We use a paint gun sprayer and GMC citrus cleaner, very heavily diluted (about 100 to 1). We blow this through the hoses, then blow air to dry the hose. The ends are cleaned and dried.

While I completely agree with FPPF that 90 durometer o-rings are probably the best application for the HP spool, most of the spools we purchase have what I suspect are nitrile 70 durometer o-rings. We also have stock spools with 75 durometer viton o-rings installed. When we do actually replace these little o-rings, I prefer to replace them with nitrile 90.

Phil Ellis
Discount Scuba Gear at DiveSports.com - Buy Scuba Diving Equipment & Snorkeling Equipment

 

[Bubbletrubble]

While I completely agree with FPPF that 90 durometer o-rings are probably the best application for the HP spool, most of the spools we purchase have what I suspect are nitrile 70 durometer o-rings. We also have stock spools with 75 durometer viton o-rings installed. When we do actually replace these little o-rings, I prefer to replace them with nitrile 90.

@PhilEllis: Thanks for the info. After looking at the HP spool spares that I have, the o-rings do appear to be either 70A or 75A durometer and possibly made of nitrile. I guess that's why I was interested. It seems like a strange choice for manufacturers to install HP spool o-rings with a suboptimal durometer.

 

[PhilEllis]

@PhilEllis: Thanks for the info. After looking at the HP spool spares that I have, the o-rings do appear to be either 70A or 75A durometer and possibly made of nitrile. I guess that's why I was interested. It seems like a strange choice for manufacturers to install HP spool o-rings with a suboptimal durometer.

Well, I think it is unfair to call their choice "suboptimal". I think they probably have their reasoning, and I suspect it is based on some degree of engineering choice. Unfortunately, there are few opportunities to fully understand WHY they make the choices they make.

Phil Ellis
Discount Scuba Gear at DiveSports.com - Buy Scuba Diving Equipment & Snorkeling Equipment

 

[Bubbletrubble]

Well, I think it is unfair to call their choice "suboptimal". I think they probably have their reasoning, and I suspect it is based on some degree of engineering choice. Unfortunately, there are few opportunities to fully understand WHY they make the choices they make.

Fair enough. That's a valid point.

 

[Doc Harry]

Thanks, Phil.

Always great service from Dive Sports, and why you should send your regs to them!

 

[SDAnderson]

The spindle is one of the ugliest place we see inside a rig with lots of wear, abrasion residue and just plain old funky goo. Because of that, at a minimum we always pull the SPG, clean the spindle and both landings and replace the o-rings at every annual service.

90 Shore Viton would be my normal choice for something that dynamic and subjected to that kind of pressure but they're so stiff that many of them crack during installation - 90's just aren't meant to stretch much, especially if you're using a bullet to ease them over the shoulder. If the crack is dramatic, it's easy to detect during installation but if it's subtle you can easily miss it and they'll hang in there for a few dives before they fail. I tried 85's without much improvement and have settled on 75's - they're not as hard as the book may call for but they usually last at least a year and have fewer short-term failures than the harder versions.

Then there's the Schrader valves and other assorted quick-disconnects...:shocked2:

 

[fppf]

Then there's the Schrader valves and other assorted quick-disconnects...:shocked2:

Yeah, don't even get me started on that one!

Working with tiny stiff orings is a lot tougher, there is an art to it.