[PSUBS-MAILIST] Hydraulic idea

[Sean T. Stevenson via Personal_Submersibles]

How do you intend to control the pressure on the receive tank? Just vent it through a check valve to the water? You need to design carefully to prevent contamination in either direction.

I wouldn't use air as the drive gas under high pressures, in order to prevent oxidation of the oil. Charge with nitrogen if you intend to do this.

To generate the same drive capability as a hydraulic pump, you are talking about very high precharge pressure - approaching the pressure at which HP bottled gas is supplied, unless you can source e.g. 6000 psi nitrogen and regulate it down to 2500-5000 depending on your manipulator requirements. In any case, if your cylinders are single acting, or even dual acting with a single rod, you have to contend with the force from the ambient water pressure, so your receive tank pressure needs to be this at minimum, and with a pressure reservoir source instead of a pump, that available delta-P is further reduced the moment you demand any fluid from the system (i.e. HP bottle pressure will drop), so your manipulator becomes weaker over time.

Just a few things to think about.

Sean



On November 25, 2016 5:25:47 AM MST, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>Hi All,I have an idea to replace the hydraulic pump for my new
>manipulator with a air over hydraulic system.  It is quite simple, the
>hydraulic oil reservoir is a hp tank that can be pressurized from a
>designated HP supply.  The oil return goes to another HP tank  to
>receive the oil.  This eliminates the pump completely and that is a
>dream.  The manipulator can go through 54 complete extensions and
>retractions, that is 54 complete movements of all functions.  After the
>oil is used up, the oil can be returned to the pressure tank by
>reversing the air flow.Hank
>
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