New Database to Ease Hazard Assessments on Oxygen Systems
The Oxygen Compatibility Assessment (OCA) team at NASA’s White Sands Test Facility (WSTF) created a Web-based OCA database that will be available agency-wide within the next year.
The database houses engineering notes from past OCAs, which provide a systematic approach for identifying and addressing fire hazards in oxygen systems.
The biggest risk of using oxygen at elevated concentrations and pressures is that materials become more flammable — easier to ignite at a faster burn rate — making an event, should one occur, much more intense. When assessing an oxygen system, the OCA team looks at the materials being used as well as the configuration, and tests to see whether the materials burn and if so, how easily. This data is then used to determine if a system is safe.
The database, which will be available behind the firewall on nasa.gov, provides an easy-to-search archive of all past OCAs. The WSTF team developed the database to allow quick responses when problems arise during testing, flight readiness reviews or missions themselves. The team can review the original OCA, see what was and wasn’t analyzed, and determine the probability of ignition under various circumstances.
“Having that data on hand and easily searchable is almost priceless because it allows us to get back to people with answers,” said Stephen Peralta, OCA team project manager at WSTF.
The database includes OCAs from propulsion systems for the military, valve support for Kennedy Space Center, and flight hardware such as the shuttle and Space Station, among others.
The group chose to collect engineering notes instead of raw data because assessing oxygen systems is very subjective; for this reason, a collection of rationale is more appropriate than a tool that uses entered data to calculate an answer.
“Because of the way that oxygen systems are assessed and the way the data has to be generated, the application is subjective,” said Peralta. “Flammability and ignition test data needs to be interpreted and can rarely be applied objectively due to configuration differences between the test and real application. The engineer’s notes in the database provide the rationale and application of the data.”
The engineering notes provide database users with the engineer’s insights on the applicable risks, how the data was applied and details of what was taken into consideration. Being able to reference previous engineers’ rationales allows engineers to complete assessments of new systems much faster. The database also produces a report for each assessed oxygen system based on the entered notes, saving the engineer from having to hand-write it. These advantages have cut the time it takes for the WSTF team to complete an OCA in half.
Developing the Database
The Web tool is not the first rendition of the oxygen database. The team first realized the need for a collection of OCAs in the early 2000s.
“What we noticed [when completing an assessment] was [that] we kept borrowing data from previous analyses of other assessments we’d performed,” said Peralta. “So if we are always going back-and-forth getting data, why not build something to hold all of that?”
The team built a software program to hold all the data. Although the archive was helpful, the team was updating the information constantly, and every time an update happened, every user had to be given the new software.
This drove the team to look at Web-based options with database management on the backend and an easily accessible website for the frontend. The Web tool allows the team to update the content whenever they need to without creating downtime for the users.
The database has been working well at WSTF, and soon will be available agency-wide. Users will be able to review content in the system and also add their own OCA data.
“A lot of people were asking for some of our assessments [that] we’d done in the past, so we thought, ‘Why not open up the tool in a way that gives people access to it, and hopefully [allows them to] contribute to it as well,’” said Peralta.
Although the primary users of the database will be engineers or designers designing a new oxygen system, other groups may be interested in the data. Engineers working on large propulsion systems like Space Launch Systems or smaller environmental and life support systems like those for Orion or multi-purpose crew vehicles could benefit from the available information.
Peralta notes that others may use the system when considering components that have been used before, but they need to keep in mind that this information is based on past systems and is not the be-all and end-all for every system.
“We caution them that just because something was analyzed and assessed safely, doesn’t mean it’s also safe for their operation,” he said.
Although the audience for this database is small, the potential impact is immense. It will allow the agency to build on and learn from its past experience while improving the efficiency and effectiveness of OCAs.