Adding adjustment knob for XTX40?

[tony28898]

Hi,

Got two XTX40s for SM and wonder whether it is worth upgrading to XTX50 by installing the knob manually. I have experience using XTX50 in BM and I did not ever use the knob as they are correctly tuned and I am satisfied with the cracking pressure by default. Here are the questions would seek your advice -

1. Actually, in what situation you might use the adjustment knob, given that your regulator is tuned properly? The regs will be used in SM diving.
2. Is there any method to adjust the cracking pressure without installing the knob?
3. Can you suggest where I can get the knob for the installation? Has been searching for it for a while but either they are sold out or not available.

Thank you in advance!

Ryo

 

[BoltSnap]

Do you know for fact that you can add the adjustment knob to the XTX40's to make it a XTX50 or are you just guessing that it can?

 

[tony28898]

Hi thanks for the reply. I read the posts and understood that the kob can be added to xtx40 and turn it a 50, just I'm not sure in which situation the knob will be used, and I couldn't find the knob parts elsewhere.

 

[axxel57]

No problem to change the knob, any descant Aqualung Dealer should be able to get it for you.
The possibility to adjust the 2nd by hand also during the dive can play a role when diving in stronger currents where the currents can trigger free flow of the 2nd or octo.
Another point is the possibility to adjust the cracking effort perfectly to an adjuster position that is not completely screwed outwards.
In case of a really strenuous, stressy dive you still can screw out the adjuster completely, producing a very slight free flow to make sure that you get optimal air supply for that part of the dive.
Since that situations usually hardly ever happen, normally a well adjusted 2nd is suitable for 98% of all dive profiles, so I never really needed that feature in my pro career in thousands of dives.
Of course you can adjust the cracking effort of your XTX40 by using an Allen Key, you just cannot do that while diving.
I would just leave the XTX40s as they are.......

 

[BoltSnap]

I would just leave the XTX40s as they are..

Does this statement means that you are recommending against putting the adjustment knob in the xtx40s?

 

[BoltSnap]

No problem to change the knob, any descant Aqualung Dealer should be able to get it for you.
The possibility to adjust the 2nd by hand also during the dive can play a role when diving in stronger currents where the currents can trigger free flow of the 2nd or octo.

I find the adjustment knob to help in preventing free flows from main and alternate second stage when swimming on surface or at anytime the second stage is out of the diver's mouth above or below the surface. It has been very useful feature to have for me.

 

[axxel57]

I know what you mean, but in fact are about 90 % of the 2nds with adjustable knobs stucked and hardly or not at all to turn by hand when I get them on my work bench, so almost nobody uses them it seems to me.
I have no problems with these knobs, but most of time it's enough to switch the Venturi Assist to 'Pre Dive' to avoid free flow (if available), and octos are often anyway adjusted a bit harder.
What I mean is that if I have already two XTX40s which work fine, I don't see a real benefit in 'upgrading' them to XTX50s.
But if someone is used to it or likes it, why not?

 

[BoltSnap]

about 90 % of the 2nds with adjustable knobs stucked and hardly or not at all to turn by hand when I get them on my work bench, so almost nobody uses them it seems to me.

You are probably seeing the ones from people that don't take care of their equipment but not the ones from people that do take care of their equipment

octos are often anyway adjusted a bit harder.

I use "primary donate" configuration so the "octo" will be used by me when I donate my primary and hence I want my octo/alternate to breathe just like my primary.

What I mean is that if I have already two XTX40s which work fine, I don't see a real benefit in 'upgrading' them to XTX50s.

If they work fine without any issues and their performance is where it should, no reason to "upgrade" them. For somebody like me and bought them used, I'd upgrade just to have it as all of my current regulator have the adjustment knob.

 

[tony28898]

You are probably seeing the ones from people that don't take care of their equipment but not the ones from people that do take care of their equipment



I use "primary donate" configuration so the "octo" will be used by me when I donate my primary and hence I want my octo/alternate to breathe just like my primary.




If they work fine without any issues and their performance is where it should, no reason to "upgrade" them. For somebody like me and bought them used, I'd upgrade just to have it as all of my current regulator have the adjustment knob.

Although I bought my regs new I still think this feature could somehow be useful. Found a compatible knob at $15 on ebay and decided to give it a go

 

[tony28898]

Just drop the link of the knob in case anyone needs that in the future :
Link to ebay