Tightening Exhaust Control

Motor vehicles account for an esti mated 60% of the pollutants that contaminate the nation's atmosphere. To combat this growing menace, Congress empowered Health, Education and Welfare Secretary John W. Gardner to limit such pollutants. As a result automobile manufacturers have installed exhaust controls on 1968 model cars. To meet this year's HEW standards, the new control devices must reduce the emission of hydrocarbons and carbon monoxide, major sources of automotive pollution, by 60% and 50% respectively. But even this improvement will be more than counterbalanced as the number of U.S. cars increases each year. Faced with that fact, Gardner last week proposed even tighter standards for 1970.

Gardner's proposals call for an elimination of 77% of the hydrocarbons and 68% of the carbon monoxide released through an automobile's exhaust pipe. How close has U.S. industry come to producing a device that would satisfy the proposed 1970 standards? At least one control system, said Interior Secretary Stewart Udall last week, has shown that "technology already exists that can be adapted to the internal-combustion engine to meet the air-pollution standards proposed for it."

Within Limits. The new device, now undergoing tests by the Interior Department's Bureau of Mines, is called an exhaust-manifold reactor. Developed by Du Pont over the past two years, the reactor system would replace the regular manifold unit on U.S. vehicles. It consists of two 4 1/2-in. by 22-in. alloy-coated stainless-steel cylinders that fit over the sides of a standard V-8 engine. (Only one reactor is required for a six-cylinder model.) As high-temperature exhaust gases flow into the reactors, air is blown into them by a small pump, causing a more complete burning of the fumes. Reduced in hydrocarbons and carbon monoxide as a result, the vapors are then piped out through the car's conventional exhaust system.

Tests of the device, conducted at the bureau's Bartlesville, Okla., petroleum research center, will continue through July. Thus far, they have demonstrated that the reactor can cut automotive hydrocarbon exhaust to less than 70 parts per million, compared with an average of 900 p. p.m. in exhaust from cars unequipped with pollution-control units. Carbon monoxide has been reduced to less than .7% of the total exhaust from a car equipped with the reactor. Both figures are well within the 1970 standards proposed last week. Nonetheless, said one Du Pont official, the unit is far from commercially feasible. Yet to come: additional testing, reduction of the reactor's size, and selection of low-cost durable materials.

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