Three-Way Catalyst Systems for LPG-Powered Forklift Trucks

MISSISSAUGA, ON -- June 16, 1997 -- Nett Technologies Inc. developed a retrofit, three-way catalyst system for LPG-powered forklift trucks. The emission control kit includes a three-way catalytic muffler, an oxygen sensor, and a digital air to fuel ratio controller. The system efficiently removes carbon monoxide, nitrogen oxides, and hydrocarbons from LPG exhaust gases. It is intended for forklifts operating in confined areas, where it can improve the air quality and help to meet the occupational safety and health standards.

Three-way catalyst in conjunction with an air to fuel ratio controller is the most effective method of cleaning spark-ignition engine exhaust gases available today. This technology has been used on automobiles since the introduction of electronic fuel injection.; Now, with the availability of digital air to fuel ratio controllers designed for LPG fuel systems, the three-way catalyst technology, with its unsurpassed exhaust gas purification, can be applied on forklift trucks.

The Nett emission control kit includes a platinum-rhodium, three-way catalyst built into a muffler. The catalytic muffler is a direct-fit replacement of the original muffler to reduce the installation cost to minimum. To ensure high efficiency of the catalyst, a digital air to fuel ratio controller, supplied as part of the kit, is installed on the truck. The controller receives a feedback signal from a zirconia oxygen sensor ("lambda" sensor) placed at the inlet to the muffler. Stoichiometric air to fuel ratio is realized by a solenoid valve which biases pressure on the fuel converter membrane using vacuum and, thus, controls the amount of fuel supplied to the mixer. In addition to the emission benefits, the application of the system improves the overall fuel economy of the truck.

Propane exhaust gases contain substantial quantities of carbon monoxide (CO) which is a big problem in all confined space applications. CO is toxic and poses a health hazard to the workers. Typical symptoms include frequent headaches and dizziness but more serious poisoning including fatal accidents may occur after a prolonged exposure to high levels of carbon monoxide. Another important pollutant found in LPG exhaust gases is nitrogen oxides (NOx). NOx levels produced by LPG engines are usually higher than those in gasoline exhaust gases. NOx is very toxic to humans and detrimental to some industrial products, e.g. paper stock. The maximum allowable levels of CO and NOx in the ambient air at the workplace are regulated by the occupational safety and health authorities (OSHA). Nett three-way catalytic mufflers are new and the most effective means of controlling these emissions. Oxidation catalyst systems, traditionally used on LPG forklifts, are not effective in controlling NOx. Lean-biased fuel controllers, sometimes used as a means of CO control, increase NOx emissions and their overall benefit is frequently questionable.

Nett Technologies Inc. specializes in emission control products for engines, vehicles, and machinery used in material handling, construction, and mining industries. A wide range of products available from Nett includes catalytic converters for diesel, natural gas, LPG, and gasoline engines, diesel particulate filters, and fume diluters.