Читать книгу Hydraulic Fluid Power - Andrea Vacca - Страница 27

A good summary of the main properties of different hydraulic fluids is provided in Table 2.2. This summarizes the data that can be found in literature [11], although one must consider that the use of additives can significantly alter the properties indicated in the table. Notwithstanding, the table is particularly significant in its last column, which quantifies the relative costs of different fluids. Assuming the reference cost of a mineral oil being 100 (the actual value fluctuates depending on several economic factors), the cost of all other oils is at least double. This is the main reason for the popularity of mineral‐based oils.

Table 2.2 Comparison between different hydraulic fluids.

Source: Adapted from Assofluid [11].

Fluid	Density (kg/m3)	Viscosity Index (VI)	Lubricating power	Fire resistance	Antioxidizing power	Maximum temperature (°C)	Toxicity	Average cost
Mineral oil	870–900	70–100	Excellent	Poor	Excellent	−5 to 70	Low	100
Vegetable oila	920	210	Excellent	Good	Fairly good	−10 to 70	No toxicity	250
Polyglycolsa	1100	150–200	Excellent	Good	Good	−30 to 80	No toxicity	350
Synthetic estersa	920	200	Excellent	Good	Good	−30 to 100	No toxicity	700
Water‐in‐oil	915–940	High	Fairly good	Excellent	Good	0–50	Low	200
Water glycol	1060	High	Fairly good	Excellent	Good	0–50	Low	400
Chlorinated hydrocarbons	1430	Low	Good	Good	Fairly good	−5 to 70	High	700
Phosphoric esters	1270	Low	Excellent	Good	Fairly good	−5 to 70	High	500
Mixture of esters and chlorides	1150	Low	Excellent	Good	Fairly good	−5 to 70	High	600
Silicones	930–1030	High	Fairly good	Excellent	Fairly good	−5 to 90	Low	<700

^a Refers to biodegradable fluids.