Work Item
ASTM WK89445

Revision of D1238-23a Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer

Rationale

Change timing device tolerances from seconds to percentages. Timing device/system accuracy requirements in section 6.6 & 6.6.1 are currently given in seconds (0.1 for procedure A, 0.01 for procedures B-D). This accuracy is impossible to verify as the uncertainty of measurement due to human error is several times greater than the tolerance, therefore I am proposing the accuracy requirements be changed from seconds to percentage. Percentage tolerance allows for a decreased effect of the human error on verification (by using longer verification times) and is a superior to seconds as a benchmark of actual test accuracy. (eg. If a test extrudes for 5 seconds then 0.1 seconds error is significant to the results, if the test runs for 5 minutes 0.1 seconds is insignificant.)

Details

Developed by Subcommittee: D20.30

Committee: D20

Staff Manager: Alyson Fick

Work Item Status

Date Initiated: 01-27-2024

Technical Contact: Brian Bushey