Document ID: chunk:federal_register_of_legislation:F2011C00805:reg:3:p2
Version: federal_register_of_legislation:F2011C00805
Segment Type: reg
Provision Reference: reg 3 (pt 2/18)
Character Range: 302435–305556

IV TEST
(Determination of evaporative emissions from vehicles
with positive-ignition engines)

         1. INTRODUCTION

         This Annex describes the procedure of the Type IV test according to paragraph 5.3.4. of this Regulation.

         This procedure describes a method for the determination of the loss of hydrocarbons by evaporation from the fuel systems of vehicles with positive-ignition engines.

         2.  DESCRIPTION OF TEST

         The evaporative emissions test (Figure 7/1 below) is designed to determine hydrocarbon evaporative emissions as a consequence of diurnal temperatures fluctuation, hot soaks during parking, and urban driving. The test consists of these phases:

         2.1. test preparation including an urban (Part One) and extra-urban (Part Two) driving cycle,

         2.2. hot soak loss determination,

         2.3. diurnal loss determination.

         Mass emissions of hydrocarbons from the hot soak and the diurnal loss phases are added up to provide an overall result for the test.

         3.  VEHICLE AND FUEL

         3.1.  Vehicle

         3.1.1.  The vehicle shall be in good mechanical condition and have been run in and driven at least 3,000 km before the test. The evaporative emission control system shall be connected and have been functioning correctly over this period and the carbon canister(s) shall have been subject to normal use, neither undergoing abnormal purging nor abnormal loading.

         3.2.  Fuel

         3.2.1.  The appropriate reference fuel shall be used, as defined in Annex 10 to this Regulation.

         4. TEST EQUIPMENT FOR EVAPORATIVE TEST

         4.1.  Chassis dynamometer

         The chassis dynamometer shall meet the requirements of Annex 4.

         4.2.  Evaporative emission measurement enclosure

           The evaporative emission measurement enclosure shall be a gas-tight rectangular measuring chamber able to contain the vehicle under test. The vehicle shall be accessible from all sides and the enclosure when sealed shall be gas-tight in accordance with Appendix 1 to this Annex. The inner surface of the enclosure shall be impermeable and non-reactive to hydrocarbons. The temperature conditioning system shall be capable of controlling the internal enclosure air temperature to follow the prescribed temperature versus time profile throughout the test, and an average tolerance of  1 K over the duration of the test.

         The control system shall be tuned to provide a smooth temperature pattern that has a minimum of overshoot, hunting, and instability about the desired long-term ambient temperature profile. Interior surface temperatures shall not be less than 278 K (5 C) nor more than 328 K (55 C) at any time during the diurnal emission test.

         Wall design shall be such as to promote good dissipation of heat. Interior surface temperatures shall not be below 293 K (20 C), nor above 325 K (52 C) for the duration of the hot soak rest.

         To accommodate the volume changes due to enclosure temperature changes, either a variable-volume or fixed-volume enclosure may be used.