Open AccessGeneration Rate of Carbon Monoxide from CO 2 Arc Welding
Author(s) -
Ojima June
Publication year - 2013
Publication title -
journal of occupational health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 59
ISSN - 1348-9585
DOI - 10.1539/joh.12-0180-br
Subject(s) - carbon monoxide , environmental science , welding , arc (geometry) , materials science , metallurgy , chemistry , engineering , mechanical engineering , biochemistry , catalysis
Generation Rate of Carbon Monoxide from CO 2 Arc Welding: Jun OJIMA. National Institute of Occupational Safety and Health—Objectives CO poisoning has been a serious industrial hazard in Japanese workplaces. Although incomplete combustion is the major cause of CO generation, there is a risk of CO poisoning during some welding operations. The aim of the present study was to evaluate the generation rate of CO from CO 2 arc welding under controlled laboratory conditions and estimate the ventilation requirements for the prevention of CO poisoning. Methods Bead on plate welding was carried out with an automatic welding robot on a rolled steel base metal under several conditions. The concentration of emitted CO from the welding was measured by a real‐time CO monitor in a wellventilated laboratory that was free from ambient CO contamination. The generation rate of CO was obtained from the three measurements—the flow rate of the welding exhaust gas, CO concentration in the exhaust gas and the arcing time. Then the ventilation requirement to prevent CO poisoning was calculated. Results The generation rate of CO was found to be 386−883 m l /min with a solid wire and 331−1,293 m l /min with a flux cored wire respectively. It was found that the CO concentration in a room would be maintained theoretically below the OSHA PEL (50 ppm) providing the ventilation rate in the room was 6.6−25.9 m 3 /min. The actual ventilation requirement was then estimated to be 6.6−259 m 3 /min considering incomplete mixing. Conclusions In order to prevent CO poisoning, some countermeasures against gaseous emission as well as welding fumes should be taken eagerly.