ASTM D6046 Standard Classification of Hydraulic Fluids for Environmental Impact
6. Test Methods
6.1 All testing shall be on unused fully formulated hydraulic fluids. The results of testing the components of hydraulic fluids shall not be used for purposes of this classification.
6.2 The most current version of the test method shall be used when multiple versions are available. The test methods shall be used as sources for test protocol only. Any pass/fail criteria which are implied or explicitly stated do not apply for the purposes of this classification.
6.2.1 The scope or other defining statements for each test method shall be consulted to ensure that the selected test method is appropriate for the hydraulic fluid under consideration; special attention shall be paid to the volatility of the tested fluid and the limitations of the test method reqarding volatility.
6.3 Appropriate quality assurance for all testing must be performed and reported. Good laboratory practice standards, such as OECD GLP and US EPA TSCA GLP, are acceptable.
6.4 The tests to be used for the environmental persistence portion of this classification are given in Table 4. They are ultimate or primary biodegradation tests carried out in aerobic aquatic media. Environmental persistence is a concern in environmental compartments other than aerobic fresh water, but tests for other compartments are not included at this time. See D6006 for some considerations for these tests and biodegradation testing in general.
6.4.1 The ultimate biodegradation tests listed above have been developed with the intention that they be used to measure biodegradation of pure chemical compounds. Such tests have significant caveats associated with the interpretation of their results. The impact of these caveats may be less for pure chemicals than for mixtures such as hydraulic fluids because pure chemicals are expected to exhibit first order kinetics with respect to biodegradation and to continue biodegrading at one rate until the chemical is substantially depleted. This behavior may not be followed in the biodegradation of a mixture such as a hydraulic fluid. It is possible that a mixture could undergo rapid biodegradation until one or more biodegradable components are depleted, and then the rate could significantly slow as less biodegradable components make up a larger and larger fraction of the remaining fluid.
6.4.2 The tests in Table 4 are to be used as stated in their respective test procedures with one exception. The OECD tests explicitly do not allow the use of a pre-adapted inoculum, while this classification allows the use of pre-adaptation. If a hydraulic fluid is being tested for classification using any of the OECD tests, the pre-adaptation procedure as described in one of the other test methods may be followed.
6.4.3 Biodegradation tests shall include a positive control, for example, low erucic acid rapeseed oil (LEAR) or sunflower oil or another vegetable oil which has been shown to be the equivalent of LEAR in the test being used. The purpose of the positive control is to verify the viability of the test inoculum. Viability of the inoculum is verified if the positive control produces at least 60 % theoretical CO2 or consumes at least 60 % theoretical O2.
6.5 Table 5 gives tests recommended for the acute ecotoxicity classification. Other tests which can be shown to be equivalent are also allowed.
6.5.1 All aquatic toxicity testing of hydraulic fluids which are poorly soluble in water shall be done using a water accommodated fraction (WAF) except that testing on aquatic vertebrates may be done using mechanical dispersion. Practice D6081 shall be used to prepare WAFs and mechanical dispersions and to interpret these results. All test systems shall contain oxygen levels above 60 % saturation at all times. This may be accomplished with renewals of the test system on a daily basis or at other interval necessary to maintain the required oxygen level. Testing on algae will not be done with daily renewal. Testing of aquatic invertebrates may be done using static methods. Testing for both terrestrial invertebrates and terrestrial plants may be done using direct additions of the hydraulic fluids to the soil. The results shall be calculated and reported in a manner appropriate for the testing method.
7. Keywords
7.1 biodegradation; ecotoxicity; environmental persistence; hydraulic fluid; insoluble material
