THE PROMISE OF CLEANER AIR

In the early 70’s, the U.S. Environmental Protection Agency was formed in response to growing national concern about air quality. It wasn’t long before the EPA developed emissions regulations that targeted the carcinogenic impact of dirty engine exhaust and set tough regulatory standards for engine manufacturers to develop much cleaner engines. Engine makers needed an instrument that could accurately measure the quantity of particulate pollution produced in engine exhaust. Throughout the 80’s, expensive and cumbersome full-flow constant volume sampling (CVS) systems the size of a city bus were the only measuring device the EPA would accept data from.

Rob Graze, senior engineering specialist at Caterpillar, contacted Sierra in 1991 with a proposition. Familiar with the successful relationship Sierra had forged with Caterpillar in the 80’s, providing mass flow instruments, he suggested a new exclusive instrument development partnership based on his patented Partial-Flow Dilution Tunnel design. With a strong background in particulate measurement and flow,Sierra saw the great potential. Within twelve months, the Model BG-1, a highly efficient and accurate Partial-Flow Sampling System (PFSS), the size of a refrigerator, was testing non-road engines at Caterpillar for a fraction of the cost of their CVS systems. Sierra was now in the fast growing engine emissions sampling business.

Three years later, Sierra introduced the Model BG-2. Upgraded software greatly enhanced its ability to perform precise and accurate steady-state particulate measurements. Through a worldwide technology licensing
agreement with Caterpillar, Sierra customers around the world were now able to save tens of millions of dollars through the ability to develop and certify cleaner engines faster and more efficiently.

In 2002, Sierra teamed with technology partners Caterpillar and CP Engineering to successfully develope the Model BG-3, a revolutionary PFSS advancement that was capable of both steadystate measurements for non-road engines and
transient measurements for the much larger on-road diesel market. In 2005, sufficiently impressed with both its accuracy and repeatability, the United States EPA, for the first time in history, certified Sierra’s BG-3 for use in the certification and compliance of on-road engines without need for full-flow CVS systems of the past.

The Sierra BG-3 became the first non-CVS system in history to be certified by the EPA for use in the certification and compliance of on-road engines.