API Publ 4650:1997 pdf download

API Publ 4650:1997 pdf download.ANALYSIS OF HiGH-MILEAGE- VEHICLE EMISSIONS DATA FROM LATE-MODEL, FUEL-INJECTED VEHICLES.
INFLUENCE OF MILEAGE ACCUMULATION RATES AND VEHICLE AGE ON EMISSIONS
A final evaluation performed in this study was a comparison of FTP-based emission rates from the EPA’s Hammond, indiana, 1M240 and emission factors test program and the emission rates from the HMV study.’ One complicating factor related to this comparison is that the HMV study was conducted about 4.5 years after the Hammond data were collected; thus, it represents a newer fleet of vehicles (on a model-year basis) relative to the Hammond project. In addition, although vehicles in the HMV project were limited to a maximum mileage accumulation rate of 33,000 miles per year, some of those vehicles accrued mileage at a much faster rate than modeled by MOB[LE5a. In particular, vehicles in the 3- to 6-year age range had accumulated 40,000 to 60,000 more miles than would have been predicted by MOB[LE5a.
To determine if emission control system in-use performance has improved with more recent model years, as the data from the HMV project suggest, emission rates from vehicles in EPA’s Flammond, Indiana, emission factors program were compared to those from the HMV project at equivalent ages and mileages (i.e., only vehicles with more than 100,000 miles from the Hammond database were included in this comparison). The results of this comparison for HCs are illustrated in Figure ES-3, which shows that vehicles in the HMV database have lower HC emissions, on average, than vehicles in the Hammond database, at least up through about 8.5 years of age. This age corresponds to a mean model year of 1982.7 in the Hammond database and 1987.2 in the HMV database
The vehicles tested in this program were procured at three locations – an TIM lane in Chicago Heights, Illinois, and two different IJM lanes in Phoenix, Arizona. Once procured, the vehicles were transported to Automotive Testing Laboratory’s (ATh’s) facilities in South Bend, Indiana (for the Chicago Heights vehicles) or Mesa, Arizona (for the Phoenix vehicles) for FTP testing. The test program began in April 1995 and continued through August 1996,
Based on a previous analysis of the U.S. Environmental Protection Agency’s on-road motor vehicle emission factors model, MOBILE5a, it appeared that the assumptions built into the development of the base emission rate equations were resulting in an over-prediction of emissions at high mileage for late-model vehicles (Sierra Research, 1994) EPA’s rationale for using some of those assumptions was related to the sparsity of data for vehicles at high-mileage.