Self-inflating SMBs

[Gareth J]

I know very little about rebreathers but why is inflation of a SMB a problem? Dontcha guys have bailout bottles/regulators that you can use to inflate a marker without getting off the rebreather?

Dependent on the dive, bailout cylinders may or may not be carried. On a shallow bimble, down to about 20m (60ft) I may well not bother with a stage cylinder, relying on the necklace regulator connect to the DIL if I need to bailout.

That a side, it is down to shifts in buoyancy. 90% of my diving is drysuit, so I am managing a minimum of two if not three volumes of gas.
1. The Drysuit
2. The wing
3. The counterlung.

Yes I can, and do fill a conventional DSMB from either the Stage regulator or the wing inflator.
If using the stage, then I am making myself buoyant, on OC I would breath out to counteract this and deploy the DSMB with out any effect on my depth. On CCR, breathing out shifts the gas from my lungs to the counterlung, no effect on my buoyancy, so inflating the DSMB is making me progressively more buoyant.
Using the wing kind of works, I can let gas out of the wing into the DSMB, whilst I hold onto the DSMB my buoyancy isn't changing, until I let go... when I go negative.
There is one other trick with the wing, which is to dump and inflate at the same time, this kind of works.

They are all a bit of a faf, especially when hefting cameras, a quick fire CO2 DSMB makes life easier.

That said, I do practice venting from the wing, both variants, I try to avoid the relying on the stage, partly because I'm lazy, and restowing the reg' after use is a pain in the ass at the end of the dive.

One thing to always remember if you are using the CO2 cartridge type, or the crack bottle (refillable bottle AP type), is at some point you will get to the end of the dive and find the CO2 bottle or crack bottle empty, its inevitable.

 

[guyharrisonphoto]

Just tried to order the SMB and reel from silentdiving. The SMB was out of stock, and I didn't want to pay shipping just for the reel, so I will have to wait. Bummer . . .

 

[PfcAJ]

I would never use a self inflating SMB. Even on a rebreather, switch to OC for the 10 seconds it takes to shoot the bag then go back on the loop.

The risk of a runaway ascent from a self inflating bag actually self inflating is not worth it at all. Not even a little bit.

 

[macado]

I know very little about rebreathers but why is inflation of a SMB a problem? Dontcha guys have bailout bottles/regulators that you can use to inflate a marker without getting off the rebreather?

I just keep a BC hose on my bailout bottle and use that to inflate the SMB with.

All of my bailout and deco regulators have LP inflator hoses attached to them. It's usually how I shoot my dSMB. Never any issues and I don't have to leave the loop, change volume in my wing or counterlung or deal with the possibility of a free-flowing regulator caused by using it to fill a bag.

More importantly, LP inflator hose allows me to plug overboard gas from any bottle I am caryring into my rebreather.

 

[guyharrisonphoto]

I definitely agree with the CO2 cartridge trigger ones being a risk. I remember from my horsecollar BC days they could corrode or the pull cord could snag on something and puncture the cylinder and away you go!. We all took ours off. But, the AP Valve one cannot self-inflate. You have to manually open the valve to the mini-cylinder. Seems like an intelligent fail-safe. I'm going to try it. If I don't like it, I can send it back. It also inflates thru the bottom using your secondary, or they make an adapter that converts the cylinder inflate to an LP hose inflate. All in all, it seems to be an intelligent design that makes deploying from depth easier.

I will report back once I get a chance to use it. I found it at Northeast Scuba supply and am ordering from them today.

 

[PfcAJ]

I But, the AP Valve one cannot self-inflate. You have to manually open the valve to the mini-cylinder. .

The valve can't be bumped open?

If you can open it, *something* can open it accidentally.

 

[guyharrisonphoto]

Well, the valve is tightened by hand as tight as you want to make it. The SMB, at its most exposed when clipped off, will be rolled up with the valve inside and not reachable or bump-able, and, usually it will be not only rolled up but in a pocket. So, for this thing, I see the chance of accidental inflation as zero. I see the ease of deployment as huge. So, worth a try.

 

[packrat12]

I use an open bottom DSMB. I have a LP hose with a "Trident LP Hose Air Nozzle Blower" connected on both my OC rig and my CCR using my deep bailout. Fast, easy and keeps everything clear.

 

[Tassi Devil Diver]

Diving rebreather I use two styles of SMB the Halcyon closed type that I inflate with a LP inflator and the AP self inflating type with the small crack bottle. I love my AP self inflating type and have used it for years without incident or issue. I use a Kent Tooling reel these things are so well engineered that they virtually tangle proof and indestructible (well almost indestructible, I broke mine beyond repair when rolling over the side it got caught on the under lip of the gunwale of the boat, left me hanging momentarily until the reel gave way!!) I also carry a finger spool as a back up.

Regrading accidental inflation of the self inflating types, I have tested this with my AP, when it is rolled up and Velcro strap placed around it I opened the valve, and the SMB remains bound up and air escapes out the OPV, preventing the SMB from inflating.

 

[KenGordon]

Well, the valve is tightened by hand as tight as you want to make it. The SMB, at its most exposed when clipped off, will be rolled up with the valve inside and not reachable or bump-able, and, usually it will be not only rolled up but in a pocket. So, for this thing, I see the chance of accidental inflation as zero. I see the ease of deployment as huge. So, worth a try.

I use one and find if anything it is too stiff. You still need two hands to crack it open. I try to close it again before letting go to avoid filling it with sea water. In warm water when travelling I swap the cylinder for the direct feed hose inflator.

A disadvantage is that the reel, SMB and cylinder combination starts to be quite large and a pain to stow. I use spool and co2 SMBs as backups. They can go in a drysuit pocket and be forgotten.