Biodegradability and Alternatives
There is no universally accepted definition for environmentally acceptable lubricants.  However, The American Society for Testing materials (ASTM) has formed a subcommittee to establish standards for environmentally safe lubricants.   Both petroleum and non-petroleum based lubricants will be included in the standards.   Most synthetic and mineral oils are inherently biodegradable - but persistence in the environment substantially varies.  For instance, mineral oils can persist in the environment up to three years.  Consequently, the search for more readily biodegradable lubricants is important.

The chart below was published by the ABIL Research Program's Sprint 1999 Advocate Newsletter.

CEC L-33-T-82 Test Results For Common Oils

Oil Type Amount Biodegraded
Mineral Oil 15-35 %
White Oil 25-45%
Natural & Vegetable Oil 70-100%
PAO 5-30%
Polyether 0-25%
PIB 0-25%
Phthalate & Trimellitate Esters 5-80%
Polyols & Diesters 55-100%


S. Harold, Biodegradability: Review of the Current Situation, 1993 The Lubrizol Corporation, p. 4.

From the Army Corp of Engineers Study  (http://www.wes.army.mil/)

Characteristics of Oil Alternatives

Parameter

Oil Type

Mineral Crop Polyethylen Glycol Synthetic Ester
Water solubility low solubility low solubility compatible low solubility
Mixing with mineral oil   possible not possible possible
Seal material compatibility good good limited limited
Varnish compatibility good good limited good
Low-temperature limit (°C) -20 to -30 -25 -30 -30 to -40
Price comparison 1 2 to 3 3 to 4 6
Biodegradability (%)1 -20 -99 70 to 99 10 to 90
Biodegradability (%)2 42 to 48 72 to 30 6 to 38 55 to 84
1Eichenberger 1991.
2Cheng et al. 1991.

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