help with designing thruster for rov.

eliotegli77

Hi there,
I plan to build a ROV, and am currently looking at different methods of propulsion. I do not wish to use `o` rings or seals and have considered magnetic coupling for the propellor to the electric motor, or even hydraulics. Cost is an issue. Would appreciate any advice on building a ROV. Plan to build a ROV to use in depths of around 100m. Thanks.

my_wan

A magnetic coupling sounds like the best way to avoid orings but it should not be a seperate magnetic coupling than the one that already exist between the motor and its' rotor. Have you ever seen how an small aquarium water pump works?

eliotegli77

thanks for reply, no have not seen how one works. Was thinking that the magnetic coupling may be the best option.

Danger

This came up a long time ago, with quite a long series of responses. One suggestion was to not bother sealing the motor and just flood it with mineral oil to keep water out. I can't remember the exact details, but a forum search should bring it up for you.

eliotegli77

Thanks danger, will do a search and see what comes up. Have heard of that before, sounds like a good option perhaps easier than the magnetic coupling.

FredGarvin

I guess I don't understand the aversion to using o-rings. They are easy and cheap. They will handle pretty much any pressure gradient you throw at them and have a wide variety of materials to suit any application.

brewnog

And there's plenty of bellows/labyrinth glands which will do the job wonderfully too...

FredGarvin

A labby is probably not the best for this application. They have to be constantly rotating in order to seal. If I am not correct, there are going to be times where these thrusters would not be moving. Plus to get a complete seal it would have to have a buffer supply of air from somewhere.

mo3eed

plz i want to hlep in designing thruster for ROV

ROV freek

Hi

Use lip seals and fill the whole thing with oil.
Silicone oil is best, but almost any thin floating oil can be used.
+0,3- +0,5 bar compensation on the oil is recommended.
Works fine, and no limits regarding ocean depth.

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my_wan	A magnetic coupling sounds like the best way to avoid orings but it should not be a seperate magnetic coupling than the one that already exist between the motor and its' rotor. Have you ever seen how an small aquarium water pump works?

eliotegli77	thanks for reply, no have not seen how one works. Was thinking that the magnetic coupling may be the best option.

Danger Recognitions: Gold Member	help with designing thruster for rov. This came up a long time ago, with quite a long series of responses. One suggestion was to not bother sealing the motor and just flood it with mineral oil to keep water out. I can't remember the exact details, but a forum search should bring it up for you.

FredGarvin Recognitions: Science Advisor	I guess I don't understand the aversion to using o-rings. They are easy and cheap. They will handle pretty much any pressure gradient you throw at them and have a wide variety of materials to suit any application.

brewnog Recognitions: Gold Member Science Advisor	And there's plenty of bellows/labyrinth glands which will do the job wonderfully too...

ROV freek	Hi Use lip seals and fill the whole thing with oil. Silicone oil is best, but almost any thin floating oil can be used. +0,3- +0,5 bar compensation on the oil is recommended. Works fine, and no limits regarding ocean depth.