Meg manual gas injection valve service
There was a thread recently on RBW HERE
about a sticky manual O2 inflator.
Advice was presented about how to un-stick the valve using oxygen safe
grease. This does work, however, it is
not a complete fix, just a field service to get one going until the next chance
to actually service the valve. Here is
how to perform that service with a few simple tools.
First, to remove the valve from the counterlung you
must grip the nut, which is inside the CL with one hand, and unscrew the valve
with the other. The nut is not too hard
to grasp, but you must turn the valve from its very thin base, not the body of
the valve itself. If you look closely at
the base of the valve and turn the part that normally rotates, you will see the
base is not moving. This is the part you
have to turn counterclockwise to unscrew it from the nut. 
See the thin base as shown by the red arrow
in this pic. I have seen a tool used to
place over the valve that makes it easier to grip this base, but acquiring one
might be difficult and for how often you need it, may not be worth the price.
Once you remove the valve, take a thin tipped flat
screwdriver or similar tool and peel off the front label from the
pushbutton. With careful removal, one
could reattach this and have it stay.
Under the sticker is a small allen or hex key screw,
it is metric sized and you must use the correct size or risk stripping it
out. On the back side of the valve is
another hex head that is a bit larger. The larger hex is sized 4mm and the
smaller is sized 2.5mm. If you do not have two sets of metric hex sets, there
is an imperial size (5/32) that will work on the back side. The front screw backs out counterclockwise,
while holding the rear fixed. First pic
below is the back side hex.
Under the screw and button you will find a spiral
spring, (in the picture here, the spring is actually upside down, my mistake,
please be sure yours is put back in with the larger diameter out toward the
button) remove and set aside. The rear
hex is actually the barrel of the valve and this must be pushed out from the
front. Take a hex tool that is just
smaller than the bore and push the barrel out the back side.
Slip the Orings off the barrel, and find a couple new
ones. I found a couple in my dive kit,
but I am not sure what size they are.
They must be a standard size as I had a couple in viton. Clean the
barrel in a solution of white vinegar and alcohol, rinse with fresh water and
dry. Install new viton o rings and
lubricate lightly with an oxygen compatible grease, I use Tribolube 71, of
course.
Clean the bore of the valve with alcohol or K02
Tribolube cleaner using a Q tip.
Reassemble in reverse order, be sure to tighten the
hex screw down snug so it wont loosed during normal use. Plug in the valve and test it prior to
putting it back in the counterlung. When
installing the valve back into the counterlung, be aware that there is a gasket
as well as the nut, and make sure they are both present and lined up before
threading the valve back in place.
Here see the soft gasket and the nut below it,
line these up and thread the valve into it.
Again, grip the nut and the base of the valve to
tighten it up securely. Be sure to check
the security of this connection prior to every dive. Having the valve fall out during a dive would
not be a good thing.
Ron Micjan
10JAN09
We be cave diving all this month!