Evaluation and Control of Carbon Monoxide Exposure from Propane-Fueled Forklifts

Abstract

As reported in the literature, the use of forklifts with propane-fueled motors may be one of the major sources of exposure to carbon monoxide in the workplace. Quebec regulations specify basic ventilation flow rates under conditions in companies where propane-fueled forklifts operate. These regulations are based on Industrial Ventilation, published by the American Conference of Governmental Industrial Hygienists (ACGIH). Contrary to ACGIH, however, they do not require any preventive maintenance program for these vehicles, including a tune-up based on an evaluation below 1 percent of the carbon monoxide emission in the exhaust gases, nor do they set any lower limit for the room volume below which a propane-fueled forklift should not be used. The aim of the study was to find an acceptable solution for reducing the carbon monoxide emitted by propane-fueled forklifts in order to reduce workers' exposure to carbon monoxide and maintain a good power efficiency. A strategy is then proposed for measurement and control of the carbon monoxide emitted by propane-fueled forklifts. This was done by: (1) comparing the measurement technique using an exhaust gas cooler and indicator tubes with the exhaust gas measurement technique used by mechanics, which is a four-gas analyzer with BAR-90 specifications; and (2) demonstrating the effect of routine forklift maintenance (including tune-ups based on reducing carbon monoxide emissions) on forklift operator exposure and on the contamination of forklift traffic areas. A field study was carried out during the winter on 69 propane-fueled forklifts with an average age of approximately 10 years. A portrait of propane-fueled forklift maintenance was developed using the results of the evaluation of the forklift carbon monoxide emissions, operator exposure, and traffic area contamination. To reduce carbon monoxide exposure, action was taken which consisted of information sessions and the development of a technical data sheet mainly for mechanics for tuning the carburetor systems of propane-fueled forklifts. It outlines and describes the tuning sequence as well as the importance of measuring the exhaust gases according to specific criteria and using the proper instrumentation. The preventive maintenance program's means of control, which includes the measurement of exhaust gases, may result in a reduction in carbon monoxide emissions, and consequently, a reduction in worker exposure. Compared with the alternative of increasing the ventilation rate, this is also a rather inexpensive way of maintaining the ambient air at acceptable concentrations. The situation encountered in companies demonstrates the concentrations of carbon monoxide emitted by propane-fueled forklifts and the impact of these emissions on forklift operator exposure and on the contamination of these vehicles' traffic areas. Although dilution of the contaminant by general ventilation in the working areas may result in significant reductions in concentrations, correction at the source is necessary through preventive maintenance of the propane-fueled vehicles, which in turn is based on the carbon monoxide measured by a mechanic during tune-up.