UL Standards free download UL 1439 2021 pdf download – Tests for Sharpness of Edges on Equipment UL 1439 2021 pdf download - Tests for Sharpness of Edges on Equipment. 6 Calibration of Tester 6.1 The sharp edge tester is to be calibrated so that a 1-1/2 ±0.03 lbf (6.672 ±0.133 N) is present... 02-11 Download Now