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Hello Bryce.
The two most common ways to pressure compensate are with Air or oil
filled.
With oil filled, you fill the housing with oil, and attach a flexible tube
also filled with oil, making sure there are no bubbles. As the motor descends,
the flexible tube gets compressed, thereby increasing the pressure on the oil
equalizing it with the external pressure. Because oil doesn't compress much, the
tube need not be very large.
If you are using a brushed motor, there are some problems with arcing
across the armature/brush interface making carbon deposits. Regular
cleaning is required.
The method I prefer is air compensation.
Attach an air line to the motor housing, and connect it to the first stage
regulator from a scuba tank.
As the pressure increases, the regulator adjusts to just over ambient
pressure, keeping the motor housing positive in relation to the surrounding
water.
This can work with pretty much any device with a housing or closed
system.
Some bubbles escaping through the seal lets you know that it's working. If
you see too many bubbles, the seal is going bad. If no bubbles, maybe it's time
to do some maintenance.
Pretty simple, reliable, and adaptable to more than one component.
You are not using that much air, and a single scuba tank can compensate
several devices at once.
Scuba air is clean and dry, which helps keep the motor clean.
Frank D. |