Xl4 2nd stage free flow

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Seamyq92

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Location
Saudi
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200 - 499
Hi guys, long term reader of the forum, but this is my first post so please go easy on me….

i was hoping for some advice

backstory: my regs are serviced every year by a friend and dive shop owner back in Ireland, but for now i am in Saudi Arabia with no Apeks tecs here, and i have very little trust for some of the dive shops when it comes to servicing.

i have never been trained in regulator service, but i am technically minded and i am a professional mechanical technician on various systems including balanced pneumatic systems.

i have a set of apeks regs with a free flow only on 1 second stage….

i have checked the IP and its perfect at 9 BAR, however my reg continues to free flow… if i adjust the lever hight by adjusting the Allen key where the hose attaches to the reg, i can stop the free flow, but the lever is soo low the purge button doesn’t work and the reg doesn’t breathe nice….

has anyone seen this before??

Thanks
 
I'm not too familiar with your 2nd stage, but it sounds like you need to replace the seat. I'm going to assume (someone will correct me if I'm wrong) that the apeks 2nd stages are barrel poppet, single adjustment design like the SP G250. IF that is the case, you can't adjust the lever height independently of the orifice, so if you have to tighten the orifice so much to stop the flow that the lever is way too low, the only two things that could wrong are a worn seat (most likely) or a worn spring. You could get a schematic online someplace and confirm the design, find a rebuild kit (it will include a new poppet or seat) and maybe even replace the spring as insurance if you can find one for a reasonable price. (The SP springs used to be under $5)

Make sure you depress the lever (via the purge button) anytime you turn the orifice adjustment, otherwise you are cutting into the seat with the sharp edge of the orifice.

If the design of your 2nd stage is significantly different than the SP G250, just ignore everything I wrote. :D
 
Maybe a leaky balance chamber. Mistake no balance chamber. :banghead:
 
If you're able to stop the freeflow by turning the orifice (even if it's a lot), then it has to be a leak at the orifice/seat interface. As @halocline has surmised, this is indeed (sortof) a standard barrel reg with a couple of wonky plastic bits, and he has covered the two likely causes - a seat problem or spring failure. The reg is not old enough to have spring fatigue, though it might be a fracture from a manufacturing flaw.

Here is the manual. In a pinch, any top hat seat (Apeks calls it the "MP seat") can be used to replace the existing part. Also inspect the orifice (Apeks calls the orifice the "seat" :banghead:) with your fingernail and make sure there are no "catches" as you rotate it. It is very delicate - do not allow it to get scratched. That too, could be the source of the leak, but would have required some mishandling at or since the last service.

That's a tough proposition - doing a field repair on the XL4 without prior experience. But you've already identified the danger in do-it-yourself second stage freeflow fixes: the lever drops enough that the reg is unsafe to deliver air. If you're able to replace the seat and tune with the lever high against the diaphragm, you'll be safe.

Here's the quick and dirty:
1) with the lever depressed each time you screw it in or out, screw the orifice in until it just seals;
2) then add 5 minutes on the clock (1/12 turn) to the orifice (again, while pressing on the lever);
3) then adjust the spring tension from the opposite end to get the desired cracking effort. See below...

The reg should begin to hiss when you immerse it in the sink, mouthpiece up, with the seam between the face plate and the case about 3-4cm below the surface of the water.

Oh. And good luck getting the face plate off for disassembly. "No tools are required"

BUT...
Alternatively, unscrew the orifice until the lever is back up against the back of the diaphragm. Remove the venturi knob by removing the faceplate and diaphragm and unlatching the venturi knob from the inside of the case (page 6, step 7 - but be careful without the Aqualung tool). Then use a hex key to increase spring pressure with the microadjuster, and make sure it's not just too low a spring pressure in the first place. That's unlikely, given how far you had to drop the lever, but it's worth a look.
 

Attachments

  • XL4_2stg_rev11_20.pdf
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I've been waiting with baited breath for this reply

You really are that guy, despite being a staff member, it's like magic folks your wish is rsinglers command
a pure Genie
 
This reg is the single most sensitive to adjust regulator that I tune. This reg is becoming a favorite once I learned the tricks. Yes, I have seen this before. Without the proper tools it's a pain to tune, wish I could help
 
No experience on XL4 but have been servicing my own Apeks for nearly 20 yrs.
Two usual suspects but you have eliminated one of them ie. IP of the 1 st stage.
The other is the seat.
Never understood the reason to introduce a special tool to remove the face plate(XL4).
 
From what I recall the XL4 has the same internals as an egress octo, but made to look like a "normal" reg.
I also found tuning them a pain in the butt.
 
https://www.shearwater.com/products/teric/

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