After using my BP60 mixed gas rig for the 2000 season I decided it
would be best if I shelved the unit and just used it as an O2
rig. Although I survived the season using the BP60 I was a
little disappointed at its performance and decided I was pushing it
just a little to far. The next logical step was to build my
own unit. So I thought I'd keep myself out of trouble over the
winter and build a unit from the ground up and try out a few idea's
I had brewing in my head.
It's not pretty but it works, and it's a giant leap from the BP60.
My new rig has a clear removable axial scrubber, clear center
section, split back mounted counter lungs, and is manually
flown. The scrubber canister holds 6 pounds of lime and is
made out of Acrylic tubing. The scrubber canister nests inside the
center section and an o-ring is used to keep the gas from sneaking up
between the center section and the canister. The center
section
is also made of clear Acrylic tubing. The counter lungs are made of
3mm neoprene glued together to form a cylinder and the seam and top
edge backed with nylon fabric. The CL is housed in 4" PVC
pipe with slots milled in the side to allow water movement.
The CL is attached to the top and bottom end caps with hose clamps
which then fit inside the PVC housing. I used R22D sensors
mounted in the top of the center section on the downstream side of
the scrubber. The sensors are connected to a 1 ATA display
housing using Sealcon connectors. O2 and diluent are manually
added using modified Sherwood BC inflators. The O2 is injected
into the exhale lung and the diluent is injected into the inhale
lung.
Post dive I remove the mouthpiece hoses and
insert a special muffin
fan on the exhale lung to blow dry air through the center
section. I'll usually do this overnight and this helps to get
out all the extra humidity that accumulates in the center section
and keeps the lime from getting real wet above the reaction area
where it tends to condense. The next day I'll remove the plugs
on the bottom of the lungs and after draining the condensation I'll
put a second muffin fan on the inhale lung. This passes dry
air through the lungs and keeps nastiness from growing in there.
I also made up a portable
rig that I use on trips. I found on multi-day trips that
the sorb above the reaction area gets real wet over time. It's
awful hard to dry this out by just using it after it's been sitting
over night. So after every day of diving I stick this on for a
few hours to pull out a lot of the moisture.
Although this rig works damn well there are of course changes that
need to be made. I've already been plotting what I'll do over
this winter to improve on the design. Smaller cross sectional
area, better placement of the sensors, better gas injection method,
add an O2 bleed orifice, smaller tanks, left hand valve on diluent
tank ............
I hope you enjoy taking a look at my death trap :-)
Mark