Occy freeflowing when gently submerged

[JeemyT]

Hi all,
I'm experiencing a problem where my occy - facing upwards and inside a rubber bell holder - goes into freeflow as soon it submerges into water, even very gently. I can only stop it by facing it downwards and very very slowly rotating it back up. It doesn't freeflow once underwater. It was serviced only recently, including diaphragm replacement. The purge has been adjusted to be less sensitive also. Are there any obvious problems I'm missing? Is finding a holder that faces the occy downwards my only solution? Model is Apeks XTX50
Cheers.

 

[Mobulai]

It’s mainly the facing up thing — without knowing how it’s tuned: when mouthpiece is upwards it’s ambient pressure is lower than the pressure on the inhale diaphragm, causing it to open up, this is referred to as Case Geometry Fault
It could be foxed by retuning it but beware of not droppingthe lever, or maybe the tuning hasn’t set in yet (the seat impression) — you say it’s freshly serviced so I’ll exclude other guesses
Another workaround could be turning the adjustment knob in, making it stiffer, how an octo would be
I also assume that you have it on “pre dive” Venturi setting, that helps as well

Edit: just noticed that octo is xtx40, so no adjustment knob - my bad

 

[Mobulai]

Do you know what cracking effort it was set for at service?
I would recommend you try this:

Robert Singler's video on this:

 

[happy-diver]

Model is Apeks XTX50

Screw in the knob

occy is Apeks XTX40

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[JeemyT]

Do you know what cracking effort it was set for at service?
I would recommend you try this:

Thanks Mobulai. I'll definitely give the bowl of water trick a go soon. I'm fairly certain that the issue is to do with the inhalation resistance being too low. The XTX40 occy does not come with an adjustable cracking control, but if it did it would be on the most open setting. Perhaps I'll look into getting it adjusted with a nearby dive centre. I don't suppose it can be adjusted DIY with an allan key?

 

[Mobulai]

I don't suppose it can be adjusted DIY with an allan key?

It can indeed (from the orifice side at least)— but this is where you have to be careful to not drop the lever
I’m not sure if the “other side of tge barrel” is also adjustable like that but I know you can get an adjustment knob also and upgrade it for like 20bucks

I will look into schematics when I’m back home for you to confirm if it can be adjusted from balance chamber/spring side

 

[JeemyT]

It can indeed (from the orifice side at least)— but this is where you have to be careful to not drop the lever
I’m not sure if the “other side of tge barrel” is also adjustable like that but I know you can get an adjustment knob also and upgrade it for like 20bucks

I will look into schematics when I’m back home for you to confirm if it can be adjusted from balance chamber/spring side

Just to confirm, the orifice side is the hose side or the side with the venturi ring? I had the same issue earlier in the year, but it only happened during giant stride entries. I watched my colleague remove the hose and make a slight adjustment to what I think was the lever, however I think he adjusted it in the direction to what i needed, and now it's more sensitive than before...

 

[Mobulai]

Hose side
Check out this great indepth before trying from that side — lever drop without understanding the consequences can be dangerous, at min 6 @rsingler shows one cutaway for illustration
It’s not that complex to tune a reg, but it’s precise

 

[Mobulai]

It can indeed (from the orifice side at least)— but this is where you have to be careful to not drop the lever
I’m not sure if the “other side of tge barrel” is also adjustable like that but I know you can get an adjustment knob also and upgrade it for like 20bucks

I will look into schematics when I’m back home for you to confirm if it can be adjusted from balance chamber/spring side

Indeed you can tune it from the other side as well (venturi knob side, which is the safer option)

 

[JeemyT]

Indeed you can tune it from the other side as well (venturi knob side, which is the safer option)

Cheers for the help. I tightened the cracking pressure with an Alan key a few turns. Will update tomorrow whether there's an improvement