Design reviews are crucial to the success of a project. During the review process, design objectives, possible discrepancies, and requirements can be identified that impact function, performance, safety, cost, and installation. The design review allows these factors to be weighed and incorporated into the project before attempting to build working systems.

Jonna Tarpoff recognized the importance of reviews when asked to design new fluid network connections to a cooling system originally designed by an outside engineering firm. While designing new auxiliary cooling branches, Tarpoff discovered that the original design lacked the equipment to monitor and adjust flow rates in any of the cooling branches. As a result of this finding, she conducted a comprehensive review of the entire system from heat removal targets and pump selection to instrumentation and flow balancing components. Fortunately, the original system existed only on paper and had not been purchased or built, allowing for easy corrections and upgrades.

The system under review consisted of a network of PVC pipe hung from the laboratory roof trusses and powered by a single-stage centrifugal pump. A plate-and-frame heat exchanger removed heat from the local system for transfer to a larger, sitewide cooling system. The network consisted of a main supply header and a main return header with parallel branches of the same flow area but differing lengths and pipe components.

The system was to have a local cooling network branch added for each new heat load. Each new local network branch would then connect to one of the main parallel supply branches hanging from the roof trusses. During the layout process of the new local network, Tarpoff found that the line resistance of one supply branch was now higher than the resistance in any of the other supply branches. This would lead to inadequate cooling flow unless resistances in the other supply branches were raised forcing flow to where it was needed most.

Tarpoff brought the fluid system into compliance with proper network design by adding valves to control or throttle flow. She used butterfly valves because they have a wider throttle range than most PVC-based valves. Butterfly valves were also a cost-effective option. Tarpoff's design change also called for using ultrasonic flowmeters to determine flow rates in the branches. Two ultrasonic flowmeters were purchased to be strapped to the outside of the pipe. This type of flowmeter can be moved from one branch to another branch while providing good accuracy during the balancing procedure. Even though ultrasonic flowmeters require more effort in the flow tuning process, the cost-savings over in-line flowmeters justified the selection.

In summary, design review is a required aspect of engineering design and analysis. As standard practice, Tarpoff includes a preliminary design review of any system before making changes. She also performs a design review of the revised system after design changes to ensure that all modifications are properly integrated into the full system enabling it to function as expected.

Perspective

A P.E. license is a constant reminder of an oath to professional and personal ethics required of all engineers. It reminds me to check my work in order to safeguard life and property. As an independent engineering consultant, I am required by the state to maintain licensure. However, the standards for engineering performance—for industrial/commercial applications, public works, or building projects—are the same: strive for excellence and demonstrate competency. Maintaining a P.E. license reminds me of this commitment on a daily basis."

"When technical candidates contact me for employment, I look to see how they view their engineering training. Is it just an 8-hour-a-day job to them, or is it a career and a profession? They need to demonstrate both the depth and breadth of knowledge and show that they spend extra time investing in their career. This extra time includes working overtime on the job—paid or otherwise—networking with and learning from experienced engineers, attending seminars and conferences, actively participating in professional societies, and overall, continually increasing their knowledge of their technical discipline. "

"Personal pride in my past engineering accomplishments drives me to strive for new and more complex engineering achievements. I value a P.E. license because it is a symbol of my technical achievements and a source of motivation for more progressive engineering experience."

Career Path