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For the past several years, manufacturers have been developing emission measurement systems for Super Ultra Low Emission (SULEV) measurements. The Bag Mini-Diluter (BMD) with an advanced exhaust flow measurement device is designed as an alternative to the traditional method for sampling vehicle exhaust, the constant volume sampler (CVS). Exhaust sampling instruments require system verification tests. The system verification test described and mandated for the CVS in the Code of Federal Regulations (CFR) §86.119-90(c) is a simulated test with propane. The very low concentration measurements required for SULEV regulations demand a more enhanced and accurate verification technique and procedure than the method described in the CFR. This investigation focuses on the technique and necessary equipment for verifying system integrity of the entire emission sampling system, including the Bag Mini-Diluter and the exhaust flow measurement device in the test cell.

As automakers begin to develop and certify vehicles that meet the California Air Resources Board LEV II and Environmental Protection Agency Tier II Regulations, emissions test cells must be designed and implemented that are capable of accurate low-level measurements. A new test cell has been installed at Ford Motor Company for use in testing vehicles that meet the stringent Partial Zero Emission Vehicle tailpipe requirements (NMOG = 10 mg/mile, NOx = 20 mg/mile). This test cell includes a redesigned Bag Mini-Diluter (BMD), improved analytical benches, an ultrasonic exhaust flow meter with an integrated tailpipe pressure control system, a conventional constant volume sampler (CVS), and a moveable electric dynamometer. The Bag Mini-Diluter will be used as the primary sampling system for the tailpipe measurements. The moveable electric dynamometer enables the test cell to be configured so that the vehicle is moved to the test equipment rather than moving the test equipment to the vehicle.