Apeks tx 50 O-ring showing

[Scubaroo]

brian cooper once bubbled...
Question:if you apply physical pressure to the venturi sleeve/lever towards the centre of the box can you push it in and make the O-ring disappear?

Yes, I could push the one piece venturi lever/sleeve into the body of the regulator and make the o-ring disappear. The o-ring has been showing since new.

cough, cough... bought them from Dive Inn... cough cough

 

[brian cooper]

Hi to all concerned O-ringers,

I had a chat today with Apeks' Lansdon Helsby, the Technical Manager at the UK site, nice bloke and he said that he didn't mind being quoted (nice from me is a real endorsement as they won't sell me spares....) I told him about the forum topic:

They are aware of the O-ring "being visible" between the venturi lever and the body(box) ,it has been mentioned to them moreso since the introduction of their blue O-rings (higher visiblity than black) but the problem was there before.

Its a question of cummulative tolerances on the various bits that get bolted together but providing that you cannot see ALL 1/16" of the O-ring it should not fall out; even if it did it would only give a wet breathe.....
Ideally there is about 0.010" end float.
He suggests pushing the venturi fully in to get the O-ring to fit in the recess on the body and on the raised portion on the sleeve, it doesn't matter whether you fit the venturi 1st or fit the lot as an assembly.

The chrome valve tube assembly has been modified with time BUT NOT in the dimensions of the threaded end (only hole size to a slot and the shouldered end when they stopped using the"plug" and put on the adjuster).

The body/box has been modified when the heat-exchanger was fitted- the wall of the box where the tube goes through is now about 3/8" thinner to cope with the thicker exchanger.
He did reiterate that the nut/exchanger should be torqued up to tighten it (50 inch-pounds) but taking care to ensure that the lever remains square to the box top/diaphragm seating.

Wear due to sand can cause problems but shouldn't allow the cummulative effect to release the O-ring. Fit a new venturi if its worn...

I repeat Lansdon is an approachable guy,Apeks are great with their customers and he was prepared to talk to me for half an hour but..... they only deal with their dealer network so while they will talk to an independant service techie they won't sell me any bits......email him if you have any issues with their product .

Cheers

Brian

 

[Scubaroo]

Thanks for the update Brian, I have some slight wear on the venturi from sand scoring, but it doesn't look widespread enough to cause problems.

cheers

 

[Braunbehrens]

What it feels like to me is that the tube "hits" the end where the nut goes too soon, i.e. the shouldered end is a little too long.

Pushing the venturi in solves the problem, but there is nothing preventing the venturi form being pushed out again.

Even in the worst position, the O-ring is still providing a seal, so I'm not all that concerned. There isn't much pressure on that O-ring, since at that point the gas is at ambient pressure.

Here is a pic of the venturi pushed in toward the body. You can still see the O-ring, but not as much

 

[Braunbehrens]

I"m going to have a look and see if you can't put an O-ring between the venturi and the part of the tube that the adjuster screws in, so as to keep the venturi pushed tight to the body.

Another fix may be to put a second O-ring on the venturi.

 

[Braunbehrens]

OK, I think we've just about beat this one to death.

I just checked the regs again, and here is what I've come up with.

You can double up on the venturi o-ring. However, the action of the venturi becomes quite hard once you do so, even with a generous amount of lube. The o-ring is doing it's job, even when it's showing quite a bit, so I'm not going to double up on it.

The tube is in all the way, what stops it is the side of the body meeting the shoulder behind the lever. The tube cannot go any further in that direction, and there aren't any tricky parts to installing the venturi. So basically, that's just how that reg is, and it works great, so I'm not going to worry about it.

Thanks to all who replied and helped out in this thread.

Side note.

It looks like you could trap some sand in that little grove, so the updated design which slightly extends the groove for the o-ring is superior. People buying new regs may want to make sure they get the newer design.

 

[Scubaroo]

...it moved... bludgeon it again.

I finally got the Christolube in the mail to finish rebuilding my TX50. When I put the o-ring on the venturi, I defied the instructions, and installed the venturi into the body by itself first, rather than putting the venturi over the valve spindle, and installing it into the body that way. Initially the new o-ring was still showing, but now that the reg was clean (and there was no sand behind the o-ring!), I was able to "click" the venturi further into the body, completely hiding the o-ring. I then inserted the valve spindle through the venturi into the body. This appears to be how the reg was designed to be assembled, but is slightly different in the documentation. Doing it as per the rebuild docs would have resulted in the o-ring showing again. With the venturi clicked fully in, the o-ring is hidden, no grit can get behind it, the lube is protected, etc. The venturi still functions as normal.

So the solution may be as simple as rebuilding in slightly different fashion at service time - insert the venturi into the body followed by the valve spindle, rather than insert the assembled valve spindle/venturi into the body.

 

[Braunbehrens]

Scubaroo once bubbled...
...it moved... bludgeon it again.

I finally got the Christolube in the mail to finish rebuilding my TX50. When I put the o-ring on the venturi, I defied the instructions, and installed the venturi into the body by itself first, rather than putting the venturi over the valve spindle, and installing it into the body that way. Initially the new o-ring was still showing, but now that the reg was clean (and there was no sand behind the o-ring!), I was able to "click" the venturi further into the body, completely hiding the o-ring. I then inserted the valve spindle through the venturi into the body. This appears to be how the reg was designed to be assembled, but is slightly different in the documentation. Doing it as per the rebuild docs would have resulted in the o-ring showing again. With the venturi clicked fully in, the o-ring is hidden, no grit can get behind it, the lube is protected, etc. The venturi still functions as normal.

So the solution may be as simple as rebuilding in slightly different fashion at service time - insert the venturi into the body followed by the valve spindle, rather than insert the assembled valve spindle/venturi into the body.

I think you'll find that if you pull the venturi away from the body the o-ring will show. If not, then pushing and pulling will eventually make it show.

There is some play in that area, and I suspect that during normal use it gets pushed and pulled once in a while.

Maybe one solution is to push it in towards the body of the reg and then be aware of this when actuating the venturi. In other words, when working the venturi, always make sure you put a little pressure towards the body of the reg.

 

[brian cooper]

I'll go with that solution, Give it a push to the right to keep it located.

I've just, yesterday, serviced an early TX40 (non-chrome ring with the blanking plug end but with a heat exchanger) and its well worn with sand, on assembly after cleaning and greasing the O-ring was visible.
After torqueing up the nut on the heat exchanger AND the blanking plug AT THE SAME TIME (equal and opposite reaction), and watching the actuating lever to make sure it didn't twist out of square there is now about 15 thou end float and you can just see a hint of O-ring

Cheers

Brian

 

[Braunbehrens]

BTW, to whomever posted about removing the black plastic plug on the end of the adjustment knob, thank you so much! I just removed it on 4 TX50's, one new and 3 well used. The used ones all had varying degrees of corrosion behind the plug, one of them pretty severe.

What a dumb design! I love my Apeks, but that plug is completely useless, and obviously salt water will get in there and just sit there and eat at the metal.