SONIC SHEAR STABILITY OF POLYMER-CONTAINING FLUIDS: ASTM D6278
EXPLANATION
This test method evaluates the percent viscosity loss for polymer-containing fluids resulting from polymer degradation in the high shear nozzle device. Thermal or oxidative effects are minimized. This test method is not intended to predict viscosity loss in field service in different field equipment under widely varying operating conditions, which may cause lubricant viscosity to change due to thermal and oxidative changes as well as by the mechanical shearing of the polymer.
Test Method ASTM D2603 has been used for similar evaluation of shear stability, but no detailed attempt has been made to correlate the results by two methods. Test Method ASTM D5275 also shears oils in a diesel injector apparatus, but may give different results. This test method has different calibration and operational requirements than Test Method ASTM D3945. This test method uses test apparatus as defined in CEC L-14-A-93 Test Method, but differs in the period of time required for calibration.
TEST SUMMARY
The test method measures the percent viscosity loss at 100° C of polymer-containing fluids when evaluated by a diesel injector apparatus procedure that uses European diesel injector test equipment. The fluid is passed through a diesel injector nozzle at a shear rate that causes polymer molecules to degrade. The resultant degradation reduces the kinematic viscosity of the fluid under test. The percent viscosity loss is a measure of the mechanical shear stability of the polymer-containing fluid.
TEST PRECISION
Repeatability: 1.05 %
Reproducibility: 2.68 %
No estimate of bias for this test method can be justified.
