Pressure balancing vessel for water?

[Patattack]

Hey guys. I am not an engineer, so excuse my terrible use of terminology. I am building a reverse osmosis System, and am in (what seems to me) a very unique system where I need to mechanically balance the pressure of two fluids without them mixing. I saw a video online showing what was necessary, and it looks like some sort of piston that balances pressure. (URL below)

Ive found some piston accumulators, but they seem to take fluid on one side and gas on the other. I've also found some hydraulic pistons, but can you put water in a hydraulic piston instead of hydraulic fluid?

Any information on where I can find something that will nail this would be incredibly appreciated. I've been looking for months.

The water is relatively high pressure. (Around 10 to 11 bar standing pressure) but the pressure when it will be engaged will be circa 6 bar.


Hope to hear from a genius soon.

Thanks,

Patrick

Url

https://youtu.be/u8W-h5k9l4U

(patrick@raimonditaylor.com)

 

[goutam_freelance]

1. Regarding hydraulic pistons-yes you can use water in hydraulic pistons instead of water.
2. Regarding creation of pressure-It may be better to create pressure using pumps rather than a piston. For the given pressure ranges, pumps are available. For cleaning purpose you can use one or more separate pumps taking suction from the permeate line before pressure recovery equipment. For high flow in a short time you can use an accumulator with pressurized gas on one side.

Engineers, think what we have done to the environment !

https://www.linkedin.com/in/goutam-das-59743b30/

 

[Patattack]

Hey, thanks for the reply.

The reason I'm a bit scared to use pumps is the following: the feed pressure is variable, and i read that if the permeate back pressure exceeds the feed pressure by as little as a bar it can easily damage the membrane. For this reason I was hoping to find something mechanical that will balance the pressures dynamically, to avoid a situation where one pump outperforms another.

It's great news to know I can use water in a hydraulic piston. I could perhaps use a double acting piston and have both water volumes connected to either end? My next question is are there any hydraulic pistons that work with comparatively low pressures? I would need it to be quite responsive to small delta pressures ( circa 0.1 bar or so).

Presumably most hydraulic cylinders are designed for heavy duty stuff where the inherent friction in their design is not so important.

The working pressure of the system never exceeds 12 bars, but during operation the pressure I'd want to balance would be a pressure of between 4 and 6 bars.


I was also thinking perhaps I could use some sort of diaphragm accumulator. I've attached a drawing here.

 

[goutam_freelance]

Your objective appears mysterious! You want to use a positive displacement system to maintain differential pressure. In positive displacement pumps you pump fixed flow and there is no control on pressure except by relief valves. The delivery pressure is determined by system resistance. A simple flow diagram with your idea will help.

Engineers, think what we have done to the environment !

https://www.linkedin.com/in/goutam-das-59743b30/