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  • Ethylene Glycol

 

 

 

 

 

 

Ethylene Glycol (MEG)

Ethylene glycol is an organic compound primarily used as a raw material in the manufacture of polyester fibers and fabric industry, and polyethylene terephthalate resins (PET) used in bottling. A small percent is also used in industrial applications like antifreeze formulations and other industrial products. It is an odorless, colorless, syrupy, sweet-tasting liquid. Ethylene glycol is moderately toxic, with children having been particularly at risk because of its sweet taste, until it became common to add bitter flavoring to consumer antifreezes containing it.


Uses
Ethylene glycol is primarily used in antifreeze formulations (50%) and as a raw material in the manufacture of polyesters such as polyethylene terephthalate (PET) (40%).
Coolant and heat transfer agent
The major use of ethylene glycol is as a medium for convective heat transfer in, for example, automobiles and liquid cooled computers. Ethylene glycol is also commonly used in chilled water air conditioning systems that place either the chiller or air handlers outside, or systems that must cool below the freezing temperature of water. In geothermal heating/cooling systems, ethylene glycol is the fluid that transports heat through the use of a geothermal heat pump. The ethylene glycol either gains energy from the source (lake, ocean, water well) or dissipates heat to the sink, depending if the system is being used for heating or cooling.
Pure ethylene glycol has a specific heat capacity about one half that of water. So, while providing freeze protection and an increased boiling point, ethylene glycol lowers the specific heat capacity of water mixtures relative to pure water. A 50/50 mix by mass has a specific heat capacity of about 3140 J/kg°C (0.75 BTU/lb F) three quarters that of pure water, thus requiring increased flow rates in same system comparisons with water. Additionally, the increase in boiling point over pure water inhibits nucleate boiling on heat transfer surfaces thus reducing heat transfer efficiency in some cases, such as gasoline engine cylinder walls. Therefore, pure ethylene glycol should not be used as an engine coolant in most cases.


Antifreeze
Ethylene glycol disrupts hydrogen bonding when dissolved in water. Pure ethylene glycol freezes at about −12 °C (10.4 °F), but when mixed with water, the mixture does not readily crystallize, and therefore the freezing point of the mixture is depressed. Specifically, a mixture of 60% ethylene glycol and 40% water freezes at −45 °C (−49 °F). Diethylene glycol behaves similarly. It is used as a de-icing fluid for windshields and aircraft. The antifreeze capabilities of ethylene glycol have made it a component of vitrification (anticrystallization) mixtures for low-temperature preservation of biological tissues and organs. Mixture of ethylene glycol and water can also be chemically termed as Glycol Concentrate/ Compound/ Mixture/ Solution.
However, the boiling point for aqueous ethylene glycol increases monotonically with increasing ethylene glycol percentage. Thus, the use of ethylene glycol not only depresses the freezing point, but also elevates the boiling point such that the operating range for the heat transfer fluid is broadened on both ends of the temperature scale. The increase in boiling temperature is due to pure ethylene glycol having a much higher boiling point and lower vapor pressure than pure water; there is no chemical stabilization against boiling of the liquid phase at intermediate compositions, as there is against freezing.

Analysis

 Grade: MEG
 Item
Test Method
Limited
 Purity (wt%)
ASTM E-346
Min. 99.85
 Water (%wt)
ASTM E-346
Max. 0.10
 Specific gravity @ 20°C
ASTM E-1064
Max. 0.7928
 Ethanol (wt%)
ASTM D-4052
Max 0.005
 Acetone (wt%)
ASTM E-346
Max 0.003
 Permanganate time
ASTM D-1363
Greater than 50 Min.
 Non volatile matter
ASTM D-1353
Less than 8mg/1000 ml
 Distillation Range @ 760 mmHg
ASTM D-1078
Not more than 1°C and shall include 64.6°C ± 0.1°C
 Color, PT-Cobalt Scale
ASTM D-1209
Max. 5
 Carbonizable, PT-Cobalt Scale
ASTM E-346
Max. 30
 Appearance
IMPCA-003
Clear and free from suspend matter
 Odor
ASTM D-1296
Non- Residual
 Acidity as CH3COOH (wt%)
ASTM D-1613
Max. 0.003
 Alkalinity as NH3 (wt%)
ASTM D-1614
Max. 0.003
 Miscibility
ASTM D-1722
Passes test
 Iron (ppm)
ASTM E-202
Max. 0.1
 Chloride (ppm)
ASTM D-512
Max. 0.5
 Sulphur (mg/kg)
ASTM D-3961
Max. 0.5
 TMA (1)
OPTIONAL
 Aromatics (2)
OPTIONAL