The Second Stage
Second stage with venturi control lever in pre-dive position.
The second stage is as compact and lightweight as the XL4’s, and looks pretty much indistinguishable, colour apart.
Its light weight plus the positive location provided by the standard Comfo-Bite mouthpiece should make jaw fatigue a thing of the past. Certainly for me two-hour dives and four dives a day with the XL4 had been no issue.
The reusable clip that holds the mouthpiece in place and allows quick and easy replacement has also been retained.
Internally, the second stage continues with the over-balanced diaphragm design that allows the intermediate pressure between first and second stages to increase more quickly than ambient pressure on descent. The result is a regulator that Apeks claims breathes better at depth.
I couldn’t say that the effect was noticeable, but given Apeks’s reputation in the technical arena I’m not about to argue. The reg certainly stayed smooth at depth.
As you’d expect, there’s a venturi +/- switch to the left of the second stage, where it falls easily to hand.
As with the over-balanced design, I’ll admit that I’ve never really noticed much difference in breathing resistance when I’ve flipped venturi-equipped regs mid-dive to see what happens, though a friend who services regs for a living tells me I’m wrong, and that it make a very noticeable difference to him. Well, potatoes, tomatoes, the switch is there if you want it.
Time to see what the XL4+ is made of, and I waited until I could find some proper cold water, determined to see if I could make this baby freeflow. See how much dedication you get from us at DIVER?
What I did was attach it to a steel 15 and leave it immersed in a horse-trough outdoors overnight when the forecast was for frost.
The following morning the trough even had a thin layer of ice on the surface that I had to break before I could reach to press the purge on the second stage.
Gas flowed and, when I stopped purging, gas stopped. I pulled the second stage above the surface to encourage icing, and tried again.
I stood the bottle up to encourage the wet first stage to ice up, re-dunked the second stage to make sure it was wet and still couldn’t make the XL4+ freeflow.
And don’t think I just tickled the purge; I hit that sucker good and hard and held it down for a fair while before releasing it. Actually, 30 seconds, reasoning that even the slowest breathers among us won’t take only two huge breaths per minute.
I’ll be the first to admit that it wasn’t a scientific test, but after that I’ll just say that I had no hesitation using the XL4+ in water at 2°. That’s still Centigrade.