Pull Dumps — lose them

[rsingler]

I wonder if you really want to disconnect the internal wire If you or someone else pulls on the inflator than the only thing taking all the stress is the correlated hose and it’s associated connectors - often old brittle zip ties. The internal wire protects the correlated hose and prevents any real stress being applied to the hose when force is applied

Well, you have a point! The wire does theoretically limit the length of the pull. Not having it might make it more likely, rather than less, to tear the hose. Though the pin and the wire is no guarantee, as we've just read.

Interesting dilemma, because from the post above about pulling off the Air 2, and Diver0001's post before that, it's clearly still possible to do damage, even with a wire in place.

Probably simpler to just stop using it.
Jim's suggestion was good - substitute a type that has an elbow. But then, there's probably a knucklehead out there who'll pull on it anyway, and rip off the hose, lol! Darwin in action!

Thanks for thinking that through for me. For the techs out there reading along, I think the advice is to make sure to use the shortest hole in the center connector, to limit how much the corrugated hose has to be stretched to open the valve. For those using wires, make sure that the wire is the correct length for the hose in question.

 

[Dan]

I had to think about this after reading your reply to my post. Here I am at work, holding my hand up in the air pretending to be scuba diving. Wish I was..

It's not just that the mouthpiece has to be higher than the BCD bladder exit port.

The hose has to be straight because if it's raised only slightly and it's in the shape of a U, then the air will be trapped in the exhaust hose, just like water is trapped in a sink drain trap.

In order to get the hose straight enough to effectively vent the gas from the BCD, it does in fact have to be held at or above head level.

At least mine does. If I actually vent it that way. Usually I just pull on the exhaust hose. It's so much easier.

You are assuming that the inflator hose is filled with water & creating a U-trap water seal as in common sink or toilet bowl. There is no way the air could be trap in a dry U-tube (pee-trap). Have you experienced in tracing down a stinky smell & found out that was due to your pee-trap was dry? Once you pour water into the sink, the smell is gone.

I haven’t seen such flooded inflator hose situation in my 13 years, 700 dives, nor in any of my dive buddy’s BCDs. Most of the power inflator hoses I have seen, there were very little water trapped in them. As long as the inflator hose is not full of water (most of the case is true), as @StefinSB said, you can raise the inflator button / Air2 mouthpiece just above the pull dump vent, it’ll vent out the air. Try it yourself.

 

[BRT]

I've been watching this thread since Jim posted it, and my sentiments varied.
I initially thought to myself, why would I get rid of a functionality on my BCD? I would never be stupid like the guy he wrote about...
But then I got to thinking about complacency , and neglected maintenance, and old rubber. And then I saw @Diver0001 's post.

I'm going to disconnect my wire. I've concluded that the theory behind having an extra valve in a high shoulder position is good. But the basic design is flawed in every manufacturer's execution.

Having the valve opening depend upon a high resistance element like a corrugated hose and a spring-loaded valve set against a big muscle like your triceps means that fine control is just about impossible. Add in a little rotting rubber or a single zip tie, or a missing zip tie, and a deep bottom or a wall? Asking for disaster. Diver0001 confirmed it.

I've decided I can live without it, nice to have or not. If I REALLY don't want to raise my hose, and I REALLY need my left shoulder dump, lol, then I can push the little tab on my shoulder valve instead of lifting my arm.

Good post, @Capt Jim Wyatt !

As for that "Instructor", +1 to reporting him.
I know, I know..."There but for the grace of God go I", but really!

I considered removing the wire. Remember the wire is what keeps you from pulling the hose off.

 

[Dan]

I considered removing the wire. Remember the wire is what keeps you from pulling the hose off.

You meant RE-considered?

 

[Steve_C]

Valid points. I am one who uses the inflator hose. I will note that I do not see myself diving over any bottom deeper than 120 fsw in the remaining of my diving "career." I usually carry a camera in the right hand except for initial descent and final ascent. I also have limited mobility of my left shoulder. I check the hose and connections regularly. I do not yank on it. So in my risk assessment I will keep using it with contingency plans in place if it should fail. I have at least two depending on conditions.

 

[scrane]

I don't like the wire activated dump valve because it seems to be a coarse form of adjustment for an action that demands a little finesse.

 

[Centrals]

Both my rec wings have remote shoulder pull dump valve and I immediately replaced them with plain elbow.

 

[mainedvr]

You don’t want to pull on the inflator ever. If it the connection between the inflator and bladder fails you are in a world of trouble.

My first BC was a back inflate with a pull dump and while diving the wrecks in NC the whole assembly came off of the BC. I am very happy it happened on the boat and not at 120 feet. I saw the inherent dangers with this system after that. What is advertised as a convenience is an accident waiting to happen.

 

[Umuntu]

My first BC was a back inflate with a pull dump and while diving the wrecks in NC the whole assembly came off of the BC. I am very happy it happened on the boat and not at 120 feet. I saw the inherent dangers with this system after that. What is advertised as a convenience is an accident waiting to happen.

Both pull dump elbows and plain elbows can come apart with poor inspections and maintenance.

Where did it come apart ? Where the hose connects to the elbow or where the elbow connects to the bladder ?

Different manufacturers use different ways of clamping the hoses to the inflators and elbows. Some use durable special screw clamps. Some use zip ties, which with age and weather go brittle and snap easily. From what I've seen, most of the plain elbows are using zip ties which should be replaced periodically.

 

[mainedvr]

Both pull dump elbows and plain elbows can come apart with poor inspections and maintenance.

Where did it come apart ? Where the hose connects to the elbow or where the elbow connects to the bladder ?

Different manufacturers use different ways of clamping the hoses to the inflators and elbows. Some use durable special screw clamps. Some use zip ties, which with age and weather go brittle and snap easily. From what I've seen, most of the plain elbows are using zip ties which should be replaced periodically.

The complete assembly came off the BC the ring it mounts to, all that was left was a mark where it use to be. The BC had three dives on it and I was the only owner. Now it may have sat in the shops storage for who knows how long. But it came off with a gentle pull while doing my pre dive check. So yes any other could have come off, but this one came off as I used it for a pull dump. I do check the integrity of my elbows making sure they are not separating from the wing, but that awareness definitely came from that incident.