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One observation I would make is that the tube would need to be
as large as possible if you are wanting it to show water etc as my experience
with using too small a tube is that they get bubble lock. Hugh From:
owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of ShellyDalg@aol.com Hi Alan. The actuator assembly sounds pretty typical. As for the
speed of stroke, they are pretty slow for sure. Oil compensating should be
fairly easy and definitely needed if more than 15 feet or so of depth is
anticipated. My thought on this is......water is heavier than oil, and oil is
heavier than air. By making reservoirs part of the envelope, natural separation
of the three should be possible using just gravity. If a small bubble is still inside the actuator, it should
eventually work it's way to the upper reservoir. If a little water enters the
envelope, it should go to the low spot. So......if we take the actuator, encase it in a stout fiberglass
casing, bond into the casing some threaded PVC female couplings, one on top and
one on bottom. Screw into these PVC fittings some hose barb adapters, attach
some clear flexible tubing, and plug the ends with threaded PVC fittings and a
plug. This creates the oil reservoirs, above and below the actuator.
Now, as the actuator rod extends, a vacuum is created in the FRP casing, and
the oil in the reservoirs will fill that space as the flexible tubes compress.
The reservoirs would need to be large enough and flexible enough to squeeze
whether there was additional outside pressure or not. I'm thinking maybe 1 inch
diameter and 6 inches long for each. With the actuator movement pushing the oil back and forth, any
small air bubbles should work their way to the top of the upper reservoir in
short order. Like wise, if a small amount of water got in there, it would
eventually settle at the bottom of the lower reservoir. Hopefully before it did
any damage. With the clear tubing reservoirs, we can see if there's air bubbles
or water at a glance, and drain or top off as required. This was my original thoughts on the Minnkota compensation too.
I'm just not sure we need to take these devices apart. Air bubbles will find
their way to the top if we give them a path, a little agitation, and time. Gotta make a method to "top it off" that's easy so
maintenance is minimal. Now, I'll admit, I may be full of S#&* here as I've
never actually done it yet, so any criticism is welcome and appreciated. Frank
D.
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