Frequent Questions

Today, and with the Phase I complex model, there is effectively a 1 RVP difference between the Region 1 and 2 standards. In Phase II, this difference basically drops to 0 RVP. Was this intended, and why?

The Phase 2 Volatility Standards (55 FR 23658 (June 11, 1990)) provided the basis for the different RVP standards, depending on VOC Control Region, for reformulated gasoline under the Simple Model. The standards for VOC emissions performance for Phase I RFG under the Complex Model were based on the Simple Model standards, which were translated into equivalent VOC emission performance standards under the Complex Model. The Phase II RFG standards for VOC emissions performance, however, were derived using the Complex Model, which takes into account RVP and several other factors in determining VOC emissions performance. Since the Complex Model already evaluates the effect of RVP on VOC emissions performance, there was no need to make any additional RVP distinction between the two regions. (11/10/97)

This question and answer is posted at The original was posted in the Q&A posted on 11/10/97 which can found at" See Question ID 3857 for RFG (Taken from the first question on
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