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Our Vision: Experience Our Passion for Flow!®




In 1991, Caterpillar Inc. and Sierra formed a joint agreement to commercialize several Caterpillar patents to produce the Model BG-1 Partial Flow Sampling System (PFSS). Sierra followed this effort up with the Model BG-2 PFSS which features advanced software.

The flagship Sierra Model BG-3 transient PFSS is protected by nine patents with several pending. The BG-3 technology was developed in 2003 in response to pending requirements for transient cycle development and certification of non-road engines. Due to their expanded power output levels, higher mass flow rates and elevated test cycle exhaust heat content, off-road engines present a unique set of challenges to the continued use of CVS systems. Further, a need was expressed by after treatment and engine development personnel for a transient particulate sampling system deployable upstream and downstream of after treatment systems for concurrent particulate sampling to enable particle removal device efficiency studies. Read More…



Engine Particulate Emissions Products & Services:
• Transient Partial Flow Sampling Systems (also steady-state): Model BG-3

• Filter & Air Handeling Tools & Accessories: Filters, Filter Holders, Automatic Filter Changers, Air Handeling Packages, Heated Sample Lines, Filter Weighing Chambers

• Instrumentation & Measurement: Mass Flow Meters & Controllers

• Test Cell Automation: Cell Environment, In-Cell Equipment, Dynamometers

• Field Services & Consulting



Local Service & Lifetime Support

By combining superior product quality with a talented global support network of experts in over 150 locations in over 50 countries, Sierra consistently delivers quality measurement solutions for each customer and supports customers for the life of the product.




Our Mission: To be the leading manufacturer in the world of fluid flow and environmental flow measurement and control instrumentation in terms of: QD PICS (Quality, Delivery, Price, Innovation and Customer Support.)
Founded in 1971 by Dr. John G. Olin, Sierra has long been well known as a manufacturer of high-performance fluid flow measurement and control instrumentation for use in numerous industries and applications throughout the world. Adding to Sierra's expertise in fluid flow and systems integtration, Sierra founded its fast growing Environmental Flow group in 1991 which specializes in engine particulate emissions measurement and is known worldwide for its flagship partial flow sampling system called BG-3 technology. Sierra's two flow divisions, Fluid Flow and Environmental Flow, continue their leadership with a steady stream of innovative products that help customers meet tough flow challenges every day.