EMISSIONS FROM IN-USE CATALYST VEHICLES

A sample of forty-nine 1975 and 1976 catalyst equipped vehicles operated in the Albany, New York area have been tested idle "as received" condition for gaseous and particulate emissions at approximately 5,000 mile intervals. Each of the 127 tests includes a 1975 FTP, a one-hour 50 mph steady cruise, and five SET-7 (sulfate) cycles, all run on tank fuel. Catalyst vehicles in consumer use frequently exhibit idle CO significantly above levels corresponding to proper converter operation. Representative SET-7 sulfate emissions from catalyst vehicles without air pumps average 1.3 mg/mi while air pump equipped vehicles have an average value of 4.9 mg/mi. These results reflect an average fuel sulfur content of 0.017 weight percent. Vehicles with active catalysts and high idle CO yield a marked SO//2 spike upon deceleration to idle conditions. This purge contains very small amounts of particulate sulfate. Significant amounts of fuel sulfur are stored on catalysts. Except for monolith catalysts without air pumps, sulfate emissions during consecutive SET-7 cycles are reproducible after pre-conditioning by a one-hour, 50 mph steady cruise. For systems with a monolith catalyst without air pump, the pre-conditioning sequence requires a one-hour, 50 mph steady cruise followed by at least one SET-7 cycle.

  • Corporate Authors:

    Society of Automotive Engineers (SAE)

    400 Commonwealth Drive
    Warrendale, PA  United States  15096
  • Authors:
    • Gibbs, R
    • Wotzak, G
    • Byer, S
    • JOHNSON, R
    • HILL, B
    • Werner, P
  • Publication Date: 1977

Media Info

  • Features: References;
  • Pagination: 37 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00158343
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Report/Paper Numbers: SAE 770064 Preprint
  • Files: TRIS
  • Created Date: Oct 13 1977 12:00AM