Engine coolants ethylene glycol solution

Although the corrosion of pure magnesium in commercial coolants has been reported [9,31], in practice, an engine block cannot be made of pure magnesium, and the coolant cannot be pure ethylene glycol solution only. Therefore, it is important to understand the corrosion behaviour of magnesium alloys in commercial coolants. 

R.L. Chance, Electrochemical corrosion of an aluminium alloy in cavitating ethylene glycol solutions , in W.H. Ailor (ed). Engine Coolant Testing State of the Art, ASTM STP 705, American Society for Testing and Materials, Philadelphia (1980) pp. 270-283. 

Laws have been enacted in many states in an attempt to prevent the sale and distribution of deleterious antifreeze products, such as salt solutions or petroleum coolants. Even ethylene glycol engine coolants must be evaluated by testing and comparison of test results with specifications for engine coolant concentrate, such as ASTM D 3306. These tests ensure desired levels of antifreeze coolant concentrate and inhibitor are available to adequately protect cooling systems against freezing, boilover and corrosion (Fig. 2). 

Check Accuracy of Tester. Test the instrument with solutions of known freezing protection. A 33% solution of ethylene glycol engine coolant in water protects to 0°F (—18°C) and a 50% solution should indicate —34°F (—37°C) protection. 

Antifreeze Solution - A fluid, such as methanol or ethylene glycol, added to vehicle engine coolant, or used in solar heating system heat transfer fluids, to protect the systems from freezing. 

Ethylene glycol is widely used as a wintertime antifreeze solution and a summertime coolant for automobile engines. 

Solutions are addressed specifically and in more detail in Chapter 7. At this point, however, it is useful to have some imderstanding of the quantitative expression of the amount of solute dissolved in a specified amount of solution. In a relative sense, a solution that has comparatively little solute dissolved per unit volume of solution is called a dilute solution, whereas one with an amount of solute of the same order of magnitude as that of the solvent is a concentrated solution. Water saturated with air at 25 °C contains only about 8 milligrams of oxygen dissolved in 1 liter of water this composes a dilute solution of oxygen. A typical engine coolant solution contains about as much ethylene glycol (antifreeze) as it does water, so it is a concentrated solution. A solution that is at equilibrium with excess solute so that it contains the maximum amount of solute that it can dissolve is called a saturated solution. One that can still dissolve more solute is called an unsaturated solution. 

To prevent an engine block from damage by freezing and expansion of the coolant, antifreeze is mixed with water in the cooling system. The chemical name of antifreeze is ethylene glycol, and it has the chemical formula C2H 02. A solution containing 40% ethylene glycol and 60% water by mass freezes at Fahrenheit, or... 

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