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US FTP-75 Cycle
The US test procedure known as Federal Test Procedure -75 (FTP-75) is a transient cycle consisting of a typical actual driving trace for the light duty vehicles. It consists of four phases as shown on Fig 4.3.:
- Cold transition phase of 505 seconds with a weighting factor of 0.43
- Stabilized phase of 867 seconds with a weighting factor of 1.0
- Hot soak phase of 10 minutes
- Hot transition phase; repeat of first phase of 505 seconds with a weighting factor of 0.57
| Cycle Details: |
|
|
|
| Length |
11.09 miles (17.85 km) |
Max. Speed : |
56.7 mph (91.2 km/h) |
| Time |
1372 s + (600 s stop) + 505 s The first 505 s are repeated
after a 10 minute stop (hot
soak) |
Idle : |
17.3 % |
| Av. Speed |
21.3 mph (34.3 km/h) |
Steady speed : |
20.5% |
| |
|
Deceleration : |
26.5% |
| Figure 4.3 |
US FTP-75 emission test cycle for light duty vehicles; the driving cycle for motor cycles is shown by dotted line. |
The total vehicle driving schedule is of 31 minutes. In addition, after operation for 1372 seconds engine is switched off in hot condition to allow hot soaking period of 10
minutes. The total distance covered is 11.09 miles. The vehicle is preconditioned before test by soaking it for 12 hours at a temperature between 20 to 30º C. The test begins with cold start. FTP-75 procedure was the first to use CVS (Constant Volume Sampling) method for measurement of the mass of the pollutants emitted per km or mile travelled.. The sample of diluted exhaust gas with air from CVS system is collected in three separate bags, one each for the three phases of vehicle operation. The concentration of pollutant in each bag and total volume of diluted exhaust gases for each test phase is determined to calculate the mass of pollutants emitted.. Weighting factors corresponding to each phase are used to give mass emission values for the total cycle.
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