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[meccanicamg]

Hello, everyone. We often design machinery with hydraulic cylinders with mineral oil. operating pressures varying from 100 to 300 bar. oil temperature starts at 20-25°c to cold central to get to work at 40°c and sometimes up to 60°c.

I need to have a clear formulation on the compressibility of the fluid according to temperature and pressure.

shell says it compresses 0.5% each 1000psi (about 70 bar).

I found another more complete but not enough:have curves, formulas or material about it?
someone supposes a 3% every 100bar but it really seems to me an exaggeration because it means there is in a lot of air.
I'm waiting for you. Thank you in advance.

 

[Kaji]

Unfortunately, this topic also speaks very little about "elements of oleodynamics" of hoepli, although it has a general introductory chapter on the principles of physics applied to fluids

probably in several books in English the topic is more in-depth, but I know only the titles so I don't know if it specifically speaks of the behaviour of mineral oils in the field of compressibility.

1. "fluid power dynamics" di g.r. seely e j.e. bobrow:
2. "hydraulic control systems" di noah manring:
3. "fluid power engineering" in m. galal rabie:
4. "hydraulic fluids" di anthony l. watson:
5. "introduction to fluid power" di james l. johnson:
6. "fluid power circuits and controls: fundamentals and applications" di john s. cundiff e i. stanislaw s. jaroszynski:
7. "hydraulics and pneumatics: a technician's and engineer's guide" di andrew parr:

 

[TETRASTORE]

@meccanicamg, I carry some links with studies that analyze the subject of compressibility (especially on the module of compression cubica or bulk modulus) in a more or less extended way both in analytical and experimental profile. I hope they can help you.
- modeling and experimental evaluation of the effective bulk modulus for a mixture of hydraulic oil and air
- evaluation of bulk modulus of oil system with hydraulic line
- determination of undissolved air content in oil by means of a compression method
- simulation study about effects of fluid compressibility in hydraulic shock absorber based on amesim
- modeling and experimental evaluation of the effective bulk modulus for a mixture of hydraulic oil and airthen, of course, in the documents of the various suppliers of hydraulic oils, like the extract you have attached, find the indications that, in my opinion, are more dictated by a prudent experience than by experimental practice tests.

 

[meccanicamg]

Thanks, guys. As soon as I have a moment I look at the documents and tell you any developments.

for now a planner of oil plants told me he lost a bar every hundred (to make 100bar I have to give 101).

more... another race.

 

[meccanicamg]

I also found a Article explained, more than the phenomenon in general of this technician, where from a lifetime I saw his valves for retroaction hydraulic movements.
Essentially it is more face talk about bulk module and dissolved air in oil that makes losing effective volume.

this technician provides the value of 1% every 100bar.
qui instead we have a graph according to the temperature and pressure in hoses and in rigid tubes.

 

[volaff]

Bye.
Maybe this could help you.

 

[meccanicamg]

Bye.
Maybe this could help you.

It's the tabellina here....bravo!
when I have a moment put it in excel and I make it the approximation polynomial so I can go even beyond the maximum pressure of the table and interpolate between the temperatures.