Session: 10-09-01: Industrial Flows

Paper Number: 144222

144222 - Oxygen Delivery System for Closed-Circuit Escape Respirators 

In the design of self-contained breathing apparatus (or respirators), using the closed-circuit principle where the breathing gas from the user is recirculated and reconditioned in a closed loop within the apparatus is the most efficient and leads to a small size. Therefore, the closed-circuit design is favored, especially when such a respirator must be carried by the user at all times for quick deployment in an emergency or when storage for these devices is limited. The National Institute for Occupational Safety and Health, National Personal Protective Technology Laboratory is leading an effort to develop the next generation of closed-circuit escape respirators (CCERs) for use to egress in the case of an emergency. As part of this research, a unique oxygen delivery system (ODS) for these type of breathing apparatus was developed through inter-agency agreements with the United States Navy (USN) and contracts with industry. The ODS in the breathing apparatus comprises a carbon composite cylinder storing pure oxygen, a valve integrated pressure reducer (VIPR), and a demand valve (DV) that delivers the breathing gas to the user. To minimize the physical size while retaining the performance characteristics required, we employed direct metal laser sintering (DMLS) manufacturing for the VIPR body using metal alloys and very high oxygen pressures of up to 10,000 psi. This paper outlines the design, function, testing, and performance of the ODS. After a thorough analysis, initial prototypes were built and subjected to various tests, some destructive, by the USN and with third parties. Unique design features were developed and incorporated such as delayed pressurization of the high-pressure chambers within the VIPR to mitigate oxygen fires and dual-use gauge and fill ports to reduce VIPR size and eliminate high -pressure leak paths. After improvements to the initial design, final prototypes were made and successfully tested to meet the design criteria. Important results achieved included receiving DOT permits for 10,000 psi and 5,000 psi carbon composite cylinders for oxygen duty. The VIPR body bust pressure had a safety factor of 4, the maximum flow rate was 195 L/min, and the DV activation was at -150mm H₂O column in line with CCER requirements outlined in 42 Code of Federal Regulations Part 84 Subpart O. Overall, the flow characteristics of the VIPR and the system work of breathing (WOB) performance are adequate and met the design requirements for the ODS. Applied in a future design, this ODS should contribute to development of smaller CCERs than current devices and deliver oxygen according to the regulations.

Presenting Author: Rohan Fernando CDC-NIOSH

Presenting Author Biography: Senior Research Engineer at NIOSH – National Personal Protective Technology Laboratory, and based in Pittsburgh, PA. Principal investigator for respirator and other life support system technologies. Currently conducting research and studies in elastomeric respirators and their use in Healthcare settings and investigating enabling technologies for improvement of breathing air supplies for escape, rescue and shelter systems for use in emergencies. Project Office for a number of research contracts and interagency agreements.
Mechanical engineer by profession with more than 30 years’ experience in breathing protection/ life support technology involved in individual apparatus and collective protection system design, production, installation, servicing and marketing in the government and commercial sectors. Employed by NIOSH since mid-2011. Formally worked at Draeger Safety both in USA and Singapore as Technical Manager, Product Manager, Portfolio Manager in Breathing Gas, Diving and Aerospace divisions. Also, at Avon Protection Systems as Program Manager for Closed-Circuit respirators. Mechanical engineering degrees from University of Nebraska- Lincoln (M.S.), research area being experimental multi-phase flow with mathematical modeling and the University of Manchester, England, UK (BSc.(Honors)). Member of ASME and IMechE (UK). Registered as a chartered engineer (CEng) in the UK. Peer reviewed publications in respirator technology and in fluid mechanics in refereed and other journals.

Authors:

Rohan Fernando CDC-NIOSH
Brian Toole Naval Surface Warfare Center, Panama City Division
Jacob Cornman ATOR Labs