Multiple doubles sets

[DiveDay]

I'm trying to learn more about BP&W doubles setups and I'm curious about how divers use multiple doubles sets.

With a single cylinder you simply disconnect the reg, and release the cam band to attach a new cylinder for a repetitive dive. However, for BP&W doubles the cylinder tank bands are directly screwed into the backplate.

What do folks with mutiple doubles sets do? Do they have a separate BP&W for each set? Do they unscrew the backplate and screw it onto a different set? If so, isn't that error prone?

Thanks!

 

[tbone1004]

everyone I know, including myself keeps the doubles on their own, and move the backplate/wing/regs from set to set.
You can't remove the bands without draining the tanks completely or you risk all sorts of problems with the manifold.

There is supposed to be a lock washer used so you don't have to use a wrench to tighten anything and it won't come out. I have never heard of an incident like that happening, so while it certainly can happen, I'd be far more concerned about someone forgetting to close a cam band and having the tank slip *which I've seen many times*

 

[divad]

What do folks with mutiple doubles sets do? Do they have a separate BP&W for each set? Do they unscrew the backplate and screw it onto a different set? If so, isn't that error prone?

No.

The user may be error prone, but that's a user problem.

 

[stuartv]

Remove regs from twinset. Remove BP/W from twinset.

Mount BP/W on 2nd twinset. Install regs on 2nd twinset.

Dive.

No, it is not error prone. I don't even know why that article said you need to use a wrench to tighten or it's not uncommon for them to come loose. If you're using wing nuts, I would recommend a lock washer, but it's certainly not required.

However, I use these:

DGX 5/16-18 Delrin Thumbwheel Nuts, Set of Two

They go on finger tight and I've never had one be loose after a dive.

 

[DiveDay]

That makes sense! Thanks all for the quick replies.

 

[Lorenzoid]

I'm no doubles expert--only 65 hours or so in mine to date--but it seems to me that even if the wing nut loosened enough to turn freely, it would have to rotate (current? vibration?) quite a few times (5, 6 or more turns?) before it actually came off. How likely is that?

 

[BoltSnap]

However, I use these:

DGX 5/16-18 Delrin Thumbwheel Nuts, Set of Two

They go on finger tight and I've never had one be loose after a dive.

Better than ss wing nuts?

 

[stuartv]

Better than ss wing nuts?

I like them better. Others may not. More comfortable on my fingers for turning tight or loosening when they're on really tight - as compared to wing nuts with lock washers. Also, I don't use any washers with the Delrin thumbwheels, so more convenient. Only 1 part to drop and lose, per bolt, instead of 3 (a washer, a lock washer, and a wing nut).

 

[tbone1004]

Better than ss wing nuts?

yes, no galling from ss on ss and they hurt your fingers less when it's cold. Also much less prone to overtightening them because you can get less torque on there.

@Lorenzoid yes, there is a LONG way they have to come out before they come off if the bolts are adjusted properly

 

[Jack Hammer]

I'm no doubles expert--only 65 hours or so in mine to date--but it seems to me that even if the wing nut loosened enough to turn freely, it would have to rotate (current? vibration?) quite a few times (5, 6 or more turns?) before it actually came off. How likely is that?

I've had it happen with wingnuts. Lost the bottom one on a dive , the top was only a thread or so on. Learned my lesson. I push down on the plate while tightening them since. Seems to be less of an issue with Delrin nuts.