(494a) Hands-on Hydro Proof Experiment Development

This presentation will examine the details of a novel hydrostatic failure test developed for undergraduate chemical engineering unit operations courses. The experiment is was developed by both university and community college as part of a NASA MUREP project aimed at educating students through hands-on experiences and meet NASA education goals by strengthening the future workforce for NASA and the nation.

Initially, the hydrostatic test apparatus was created to support the development and testing of a 1U CubeSat green propulsion system including a polymer electrolyte membrane (PEM) electrolyzer, hydrogen and oxygen tanks and combustor. Each component of the propulsion process was custom made and required hydrostatic-pressure testing to establish operating safety margins. Furthermore, the Hydro Proof experiment contributes to the ever-increasing need for additional safety training in engineering curricula due to the significant numbers of industrial accidents each year. In 2020, someone died every 111 minutes from a work-related injury in the United States (Hess, 2021).

The experiment’s background materials, pre-lab assignments and activities emphasizes the importance of lab safety education and prioritizes a hands-on approach. There are far too many examples of pressure-related accidents such as the accident in Florida where a pressure vessel ruptured and killed several employees (Johnson, 2008). There were car door-sized pieces of quarter inch-thick steel thrown several hundred yards from the locus of the blast (Figure 1).

The Hydrostatic Failure Analysis Experiment provides opportunities for hands-on experiences with safety testing techniques. As part of the experiment, students hydrostatically test commercial polyethylene (PET) bottles to failure. As part of pre-lab activities, students calculate hoop and axial stresses and explore the importance of safety factors in process operation. Following the experiment, they compare the theoretical predictions to experimental data.

The experimental equipment including pressurization pumps (pneumatic and battery powered), pneumatic controller, inlet water filter and hydraulic lines are presented in Figure 2. Images of the pre- and post-test water bottle are shown in Figure 3.

Topics include lab safety, equipment set up, pressure testing safety, and experimental procedures. Student data obtained during a beta-test run of the experiment from Fall semester 2023 will be reviewed. The pre-lab contains several questions regarding design safety, pressure testing and the advantages of using water as opposed to compressed air. This is followed by quick calculations to determine the equivalent force in the soda bottle failure when over pressurized with air to the explosive energy contained in Trinitrotoluene (TNT). Students were also asked to propose a ‘dry lab-experiment’ to visually compare the hazards/damage potential from an over pressurization event using compressed air vs. water in a one-and-a-half-foot cube. Initial student responses to this question will be presented.

References:

• Hess, Abigail, “13 U.S. workers die on the job per day, on average—and these are the most dangerous jobs”, BLS estimates that 13 U.S. workers die on the job per day, on average (cnbc.com), accessed 3/11/2023
• Johnson, J. “Florida Explosion Investigation Yields Preliminary Results”, C&EN, 2008. http://pubsapp.acs.org/cen/news/86/i02/8602news1.html, accessed 1/21/2023