BCD Self-inflating

[LVX]

Hello all,

I have an issue I am trying to work out. So, I have a Halcyon Traveler BCD and have used it without issue for some time. I noticed this past weekend that it was self-inflating. I was able to disconnect it and then manually inflate it for the rest of the dive. I thought it would be an easy fix.

• I changed out the entire inflator hose and mechanism with a different one. That didn't work.
• I changed out the inflator hose (the small one) with a different one. That didn't work.
• I removed the entire reg set up and put on a different reg setup. That didn't work.

Now is it possible that I have 2 inflators that are both bad, yes, but unlikely. Is it possible that I have 2 small inflator hoses that are bad, yes, but again unlikely and the same for 2 reg setups.

I am at a little bit of a loss. Any thoughts?

 

[James79]

Just from a functional perspective, only thing that fits is two power inflators that both auto inflated. I'd get a cheap one from DGX and verify with it. Other way to verify the ones you have is to take the inflator off the corrugated hose, hook it to the reg set, pressurize, and put the inflator in a bowl of water to look for leaks.

 

[LVX]

Just from a functional perspective, only thing that fits is two power inflators that both auto inflated. I'd get a cheap one from DGX and verify with it. Other way to verify the ones you have is to take the inflator off the corrugated hose, hook it to the reg set, pressurize, and put the inflator in a bowl of water to look for leaks.

That is a good suggestion. I have a 3rd inflator that I use for my side-mount setup. It does not self-inflate. I think I am going to take it off and try it first. If it still inflates, I know it is not the inflator.

 

[Tanks A Lot]

The hose (LPI) that comes from your first stage can't produce an auto inflate that you are describing. A fault in that LPI-hose can at most lead to a leak between the coupling of your BCD-inflator and the LPI-hose.

An auto inflate will occur if for example the O-Rings "A" have a build up of dirt or grime. This will prevent the whole rod that they are attached to to not move freely anymore.
Theoretically other things could be at play as well, for example a broken spring. The O-Rings are the likely culprit though.

Taking these apart and cleaning them is really no big deal and can be done by everyone that has a spanner, allen key and flathead screwdriver.

 

[Gone for diving]

One problem is,
most inflators have the pressure, so it try's to open the valve, the spring is pushing back against the seat surface area of the spool, and keeping it shut.
So several things could be the problem.
Too high intermediate pressure,
Sticky orings and dirt (as mentioned)
Bad orings, or combination of all,

Tear it apart and have a good look, and fix (orings are cheap)
Also check your intermediate pressure,,, unlikely, (your reg should be leaking air ) but definitely worth a check

 

[Tanks A Lot]

I do not get a lot of these inflators into my hands, as they are just not popular where I worked, so things might get a bit fussy down below.

...most inflators have the pressure, so it try's to open the valve, the spring is pushing back against the seat surface area of the spool, and keeping it shut.

This should not be the case here. Air enters the barrel at the little hole between O-Rings "B" and "C", so it will land between the O-Rings "A" of the push pin, making this center balanced. The pressurized air will force the push pin equally towards the button, as well as the lower exit.

Taking the picture from above:
Pushing the pin that hold O-Rings "A" down are:

• Ambient pressure
• Intermediate pressure from the LPI hose acting on the lower O-Ring "A"

Pushing the pin that hold O-Rings "A" up are:

• Ambient pressure
• Intermediate pressure from the LPI hose acting on the upper O-Ring "A"
• Spring underneath the button

Ambient pressure is of course equal on both sides of the pin. The force of intermediate pressure that act on O-Ring "A" is equal on both O-Rings "A", provided they have the same diameter. Thus the determining force is the spring underneath the button, holding the mechanism closed.

I completely forgot that Halcyon switch a long time ago (That's how many of these I get into my hands...) to a inflator that is manufactured by god knows who. The same inflator can be found on tons of equipment like Highland/XS-Scuba, Atlantis, DiveRite and so forth.

DiveGearExpress has the same inflator for sale for example. They also have a neat little video that will show you the inner workings of these. They do have a special tool for sale, but a pair of snap ring pliers to a wonderful job of opening the inflator as well. In a pinch, gently mount the inflator into a vice. Then gently tap the ring, which sits underneath your inflator button and has two grooves cut into it, by putting a small screwdriver into one of these grooves.

Without seeing your exact inflator, I guess the below schematics are a more precise fit, unless your Halcyon BCD is quite old.

 

[Zeedier]

I did not read the entire conversation, but if two inflators show the same problem, my first guess would be that the middle pressure from the first stage is too high. Best regards, Jeroen