what formula gives oil temperature at a certain pressure?

[gaber26111]

Dear professional engineers,

i am working on hydraulic circuit design, and the maximum pressure at the cylinder is 24.000 PSI, and i need to select the right oil for the circuit, so i need to know its temperature at that pressure, so i select accordingly

can't get the formula which shows the relation between the pressure and temperature of oil used at hydraulic circuits, anyone can help?

will appreciate your help,
Thanks in advance

 

[MikeHalloran]

Uh, that's not how it works.

You really need to get some local help from someone with more experience in hydraulic system design.





Mike Halloran
Pembroke Pines, FL, USA

 

[gaber26111]

why it doesn't work like that at all?, may you clarify to me whats wrong?

 

[bryanoftexas]

Pressure does not appreciably affect temperature in liquids.

Process conditions and pump/motor heat dissipation are the significant factors you need to look at for temperature.

 

[Dougt115]

I believe what you are looking for is equivalent of the CTE of the hydraulic fluid. As the hydraulic fluid heats up how much will the fluid expand and what will be the resultant pressure?

If you have built the system right there should be an accumulator to prevent the increased pressure. This is why pressure and temperature are not related the way you were thinking.

If you do not have an accumulator but have instead sealed your system you can get an estimate of the pressure by using the CTE of the fluid and the CTE of the container and do a volumetric estimate as a function of temperature.

 

[hydtools]

CTE = Coefficient of Thermal Expansion

There is no relationship between pressure and temperature. Except: temperature rise due to compression, which is generally ignored; expansion of fluid due to increasing temperature and the resulting pressure if the fluid is constrained, not free to expand.

Ted

 

[gaber26111]

Thank you all for your replies,

well, i know now that there is no relation between the oil pressure and the temperature at liquids, i thought there is a relation like as the gases, but i understand now

one more question please, at the same thread and not to open new one which is:

i am considering manual pump, with built in manual relief valve, my question, is the manual relief valve which exist at the manual pump, can be opened manually at anytime while loading, and release the pressure to the tank?, or it only is adjusted manually to open at a certain range of pressure?

will appreciate your response,
Thanks

 

[hydtools]

From your description, the relief valve may be either or both. Manually adjustable or manually adjustable and manually operable. Do you have the manufacturer's specifications?

Ted

 

[gaber26111]

No hydtools,i don't have manufacture specifications yet, i just wanted to know before i go through manufacturers if that option is exist and i can adjust the relief valve manually to open at a certain pressure and to be manually opened at operation

Thanks for your help, i appreciate that