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Measurement and modeling of oxygen content in a demand mass ratio injection rebreather
KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology.
KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology.
2015 (English)In: Undersea & Hyperbaric Medicine, ISSN 1066-2936, Vol. 42, no 6, 573-592 p.Article in journal (Refereed) Published
Abstract [en]

Mechanical semi-closed rebreathers do not need oxygen sensors for their functions, thereby reducing the complexity of the system. However, testing and modeling are necessary in order to determine operational limits as well as the decompression obligation and to avoid hyperoxia and hypoxia. Two models for predicting the oxygen fraction in a demand constant mass ratio injection (DCMRI) rebreather for underwater use were compiled and compared. The model validity was tested with an IS-MIX, Interspiro AB rebreather using a metabolic simulator connected to a breathing machine inside a water-filled pressure chamber. The testing schedule ranged from 0.5-liter (L) to 3-liter tidal volumes, breathing frequencies from five to 25 breaths/minute and oxygen consumptions from 0.5 L/minute to 4 L/minute. Tests were carried out at surface and pressure profiles ranging to 920 kPa(a) (81 meters of sea water, 266 feet of sea water). The root mean squared error (RMSE) of the single-compartment model was 2.4 percent-units of oxygen for the surface test with the 30% dosage setting but was otherwise below 1% unit. For the multicompartment model the RMSE was below 1% unit of oxygen for all tests. It is believed that these models will aid divers in operational settings and may constitute a helpful tool when developing semi-closed rebreathing apparatuses.

Place, publisher, year, edition, pages
Undersea and Hyperbaric Medical Society , 2015. Vol. 42, no 6, 573-592 p.
National Category
Physiology
Identifiers
URN: urn:nbn:se:kth:diva-172946ISI: 000368748500005PubMedID: 26742257Scopus ID: 2-s2.0-84954574239OAI: oai:DiVA.org:kth-172946DiVA: diva2:850842
Note

Updated from Manuscript to Article. QC 20160118

Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2017-12-04Bibliographically approved
In thesis
1. Oxygen content in semi-closed rebreathing apparatuses for underwater use: Measurements and modeling
Open this publication in new window or tab >>Oxygen content in semi-closed rebreathing apparatuses for underwater use: Measurements and modeling
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The present series of unmanned hyperbaric tests were conducted in order to investigate the oxygen fraction variability in semi-closed underwater rebreathing apparatuses. The tested rebreathers were RB80 (Halcyon dive systems, High springs, FL, USA), IS-Mix (Interspiro AB, Stockholm, Sweden), CRABE (Aqua Lung, Carros Cedex, France), and Viper+ (Cobham plc, Davenport, IA, USA). The tests were conducted using a catalytically based propene combusting metabolic simulator. The metabolic simulator connected to a breathing simulator, both placed inside a hyperbaric pressure chamber, was first tested to demonstrate its usefulness to simulate human respiration in a hyperbaric situation. Following this the metabolic simulator was shown to be a useful tool in accident investigations as well as to assess the impact of different engineering designs and physiological variables on the oxygen content in the gas delivered to the diver by the rebreathing apparatuses. A multi-compartment model of the oxygen fractions was developed and compared to the previously published single-compartment models. The root mean squared error (RMSE) of the multi-compartment model was smaller than the RMSE for the single-compartment model, showing its usefulness to estimate the impact of different designs and physiological variables on the inspired oxygen fraction.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. x, 48 p.
Series
TRITA-STH : report, ISSN 1653-3836 ; 2015:6
Keyword
Diving, rebreather, underwater breathing apparatus, unmanned testing, hyperbaric, metabolic simulator, scuba, semi-closed
National Category
Other Medical Engineering
Research subject
Medical Technology
Identifiers
urn:nbn:se:kth:diva-172949 (URN)978-917595-616-9 (ISBN)
Public defence
2015-09-25, D2, Lindstedtsvägen 5, KTH, Stockholm, 09:00 (English)
Opponent
Supervisors
Note

QC 20150903

Available from: 2015-09-03 Created: 2015-09-02 Last updated: 2015-09-03Bibliographically approved

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