Hydraulic Fluids

Question 1

• offer low resistance to flow
• incompressible
• good lubricating qualities
• non-corrosive
• compatible with system seals and lines
• must not foam

Answer 1

These are the REQUIREMENTS of hydraulic fluid

Question 2

• Viscosity
• Chemical Stability
• Flash Point
• Fire Point

Answer 2

These CONSIDERATIONS for selecting a fluid

Question 3

Both high and low viscosity wears part prematurely why?

Answer 3

low viscosity does not provide adequate lubrication for parts which move or are subject to heavy loads

Question 4

The ability of liquid to resist oxidation and deterioration for long periods

Answer 4

Chemical stability

Question 5

• TEMPERATURE - thermal stresses can lead to acidity (unfavorable chemical changes of fluid caused by carbonization)
• VISCOSITY - critical to maintain fluid properties at various operating temperatures
• MOISTURE - can lead to corrosion and hydrolysis

Answer 5

Factors of Fluid

Question 6

The temperature at which a liquid gives off vapour in sufficient quantity to ignite MOMENTARILY when a flame is applied

Answer 6

Flashpoint

Question 7

A high ______ is desirable, as this indicates a good resistance to combustion and a low degree of evaporation at normal temperatures

Answer 7

Flash point

Question 8

The temperature at which a substance gives off vapour in sufficient quantity to ignite and CONTINUE to burn when exposed to a spark or flame

Answer 8

Fire Point

Question 9

Type of hydraulic fluid made from Castor oil and alcohol (MIL-H-7644)

used on WWII

BLUE in color

Answer 9

Vegetable - base fluid

Question 10

Type of hydraulic fluid made from kerosene-base with good lubrication qualities (MIL-H-5606)

RED in Color (Flammable)

Answer 10

Mineral (petroleum)-base fluid

Question 11

Type of fluid developed for high performance aircraft (introduced
in 1948)

Fire resistant (PURPLE)

Skydrol (MIL-H-8446) is the most commonly used synthetic fluid

Answer 11

Synthetic fluid