Appraisal method for identifying the cause of molten beads in electrical circuits in fire

Abstract

The invention discloses a method for identifying causes of melted bead formation of an electrical circuit in fire. The method comprises the following steps of (1) utilizing an electronic analysis balance to weigh mass m of a melted bead; (2) taking off the melted bead, placing a beaker filled with appropriate water on the electronic analysis balance, immersing a supporting basket hung on a tripod into the beaker, and enabling the supporting basket not to be contacted with the cup wall and the cup bottom without water overflowing; (3) enabling the electronic analysis balance to return to zero, placing the melted bead into the supporting basket to obtain reading m1 of the balance; and (4) calculating volume of the melted bead according to m and m1. Pressure of the melted bead on water, namely F-pressure is equal to buoyance of the water on the melted bead, namely F-buoyance. F-pressure= F-buoyance= m1g= Rho-watergV-water drainage, hence, V-water drainage= m1 / Rho-water, and V-water drainage is the volume of the melted bead. According to the formula Rho= m / V, Rho-melted bead= mRho-water / m1. Data obtained through a density method is visible, so that the measurement and judgement of the density of the lead melted bead have strong reliability.

Description

technical field [0001] The invention relates to a method for identifying physical evidence of fire traces, in particular to an identification method for identifying the cause of the formation of molten beads in electrical circuits in a fire. Background technique [0002] For a long time, after many years of research and exploration, my country's fire science and technology workers have established the national standard "Technical Appraisal Method for Electrical Fire Traces and Evidence". The identification of the molten beads or melt marks extracted from the fire scene provides evidence for the relationship between the cause of the molten beads and the occurrence of the fire. In the macro method (GB / T16840.1-2008), the cause of the formation of the molten bead is determined according to the void in the cross-section of the molten bead. There are cavities inside, the number of cavities is small, and most of them are distributed in the middle of the molten bead; there are cavi...

AI Technical Summary

Problems solved by technology

[0007] In order to solve the problem that the identification of the cause of the formation of wire beads cannot be quantitatively or repeatedly identified, the present invention first proposes and develops a new method for judging the cause of the formation of wire beads—the density method, which is determined by measuring the density value of wire beads The reasons for its formation successfully solved the above problems