Can any one help me in explaing use of HVI hydraulic oil than ordinary hydraulic oil & why only PMA polymer is used & why not OCP
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As you probably know the higher the VI number the more resistant the oil's viscosity is in relation to temp change. Relating this to hydraulic oils-it helps with cold start-ups, as there is an increase in the chance of pump cavitation with cold thick oil. Also helps with consistant operation as far as speed/oil flow issues i.e. hydraulic cylinder velocity will decrease with an increase in viscosity . These are only a couple of the benefits. Hope this helps,
Tom
Tom
I think that PMA is used in this application
for:
1-they have pour point depressant prpperties which are acheived by implementing long chain alkylated groups in to their molecular structure.
2-They have better shear stability
for:
1-they have pour point depressant prpperties which are acheived by implementing long chain alkylated groups in to their molecular structure.
2-They have better shear stability
PMA may not have dissolving problems that the synthetic oils are do generally with base oils than the ocp
I believe that the shear stability is achieved by whether it is a primary, secondary or tertiary group - also the size of the alkyl group. The amount and type of PMA added will impart the shear stability on the hydraulic fluid. The less cumbersome and smaller alkyl group the more shear stable it is.
There are also hydraulic oils with synthetic base oils that also impart high VI characteristics as many hydraulic oils contain 95% or more base oils as part of its formulation.
There are also hydraulic oils with synthetic base oils that also impart high VI characteristics as many hydraulic oils contain 95% or more base oils as part of its formulation.
