water hydraulic cylinder 1

[rfitts]

Does anyone have any experience with using a hydraulic cylinder with water? I am thinking of using a double acting cylinder as a spray bar oscillator. This application will require adjustable stroke and adjustable speed. Thanks in advance for any information. Bob

 

[Mandrake22]

A dozen or so years ago I worked for a manufacturer of large water works valves. These often were operated by cylinders using the city water supply they were controlling as the operating media as well. Construction materials were brass, bronze, stainless and fiberglass.
Since this is somewhat of a specialized application, finding a cylinder supplier that works with this media may take some searching.
We frequently used Carter Controls (in the Chicago area) but I think they were acquired by somebody else. Googling 5 pages deep didn't uncover any likely hits.

 

[rfitts]

Mandrake22 thanks for the reply. I think an all stainless construction sounds appropriate for the cylinder, aluminum would not hold up well in an all water application. Bob

 

[ornerynorsk]

you could try mfrs of equipment for water-based hydraulics. There are cylinders, pumps, control valves, etc all available manufactured specifically for water based systems. A cursory glance through McMaster Carr shows that they carry a limited line.

 

[rfitts]

ornerynorsk thanks for the reply. I am working with manufacturers of this stuff, but I am looking for someone with field experience using these products. How do these components hold up over time in the field. Any deigner input from somebody that has gone down this road.
Bob F itts

 

[automatic2]

rfitts, I am currently into the journey myself. I use a pnuematic cylinder to deliver a metered quantity of water based solution. I have well over 8000 cylinders in the field, and am dealing with the realities.

 

[ccw]

Hi rfitts,
First, a careful definition of the fluid requirements may be in order. When you say water based, some folks think 90/10 or water/glycol is "water based". Or do you mean "pure water" systems, eg. no additives at all allowed? You will have difficulty with well meaning salesmen, otherwise. The next primary consideration is whether or not you are going to use a closed loop system.

The nuclear industry is looking at pure water based systems to mitigate consequences of hydraulic spills and ruptures in contaminated areas. Pure water spills in contaminated hot cells just evaporate and do not cause a "mixed waste" problem. Other systems require pure water with dissolved gases such as nitrogen removed as well.

Closed loop, pure water hydraulic systems require continuous or at least periodic monitoring and treatment of the water to prevent small critters from taking up residence. This puts some otherwise strange requirements on the tank reservior such as ultraviolet light sterilizers, etc. Pure water is a relatively poor lubricant so pump/motor/actuator bearing lubrication is not simple. Pure water has low viscosity relative to more common hydraulic fluids so seal performance and wear considerations in pump/motor/valve/actuator are problematic.

 

[strokersix]

You might want to look into water-jet cutting pressure intensifiers. I think they are typically a large oil hydraulic cylinder driving a smaller water hydraulic cylinder. Perhaps there is some information available regarding material selection.

 

[EdDanzer]

Some things to be aware of if trying to use air or hydraulic cylinder in a water application.
Corrosion from electrolysis can be a problem.
Nylon wear ring will absorb moisture and change size.
Some seal materials do not work well in water.
Stainless steel is not a good plain bearing material, so a bearing material should be used between sliding surfaces. Most plastics will change size some from moisture, we use a self lubricating nylon and moisture stabilizes it to hold size. Acetal will work ok, but is not as good of a bearing material. Bronze and other metals may accelerate galvanic corrosion. Teflon and Teflon based products may work well for seals and ok for bearings.

We are not allowed to advertise in posts on this site, but you can contact me at danzco@thurston.com for additional information.

 

[flamby]

I am no expert in this field, but I do have some first hand experience of hydrostatic testing of pressure vessels. I really can not explain the reason, but water is very much compressible at high pressures. By water, I mean the tap water. Buckets of extra water goes into the vessel to create pressure upto, say 7MPa. Is this due to dissolves gases? I guess, oil is less compressible.

I will like to know. Anyone?

 

[Mandrake22]

flame,
I'm not sure of the relevance to the original question, but what you are referring to is called the bulk modulus. Using imperial units, the bulk modulus of hydraulic oil is 250,000 psi; water is 320,000 psi and steel is 23,500,000 psi.Oil is the most compressible of these three examples.
I would be willing to bet that this will have no relevance to the original inquiry.