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The safety relevance of standardized tests for diving equipment
Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences. Försvarsmakten. (Marin Teknik)ORCID iD: 0000-0002-4629-6324
2020 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Vital components are more or less prone to fail in a diving apparatus. This thesis examines the performance of oxygen sensors, carbon dioxide scrubber monitoring and composite gas cylinders. A partial pressure of oxygen sensor authentication is suggested in a published patent and poster, weaknesses in carbon dioxide scrubber monitoring systems near surface are revealed in a published paper and potential harmful gas permeability properties of a composite gas cylinder, altering the gas composition and decreases the oxygen fraction, is measured and determined in a submitted paper.The importance of adequately and thoroughly performed safety tests that are standardized becomes even more relevant when managing personal protective equipment. The European Committee for Standardization have ratified relevant standard for the work in this thesis;EN-14143 Respiratory equipment – Self-contained re-breathing diving apparatus,EN-12245:2009+A1:2011 Transportable gas cylinders – Fully wrapped composite cylinders, andISO 11119-3:2013 Gas cylinders – Refillable composite gas cylinders and tubes – Design, construction and testing.These tests form a base-line for the methods, tests and result evaluations performed here and are considered safe; however improvements to the tests and standards can be made and are here suggested.

Place, publisher, year, edition, pages
Karlskrona: Blekinge Tekniska Högskola, 2020. , p. 134
Series
Blekinge Institute of Technology Licentiate Dissertation Series, ISSN 1650-2140 ; 5
Keywords [en]
Diving, rebreather, underwater breathing apparatus, unmanned testing, hyperbaric, scuba, oxygen sensor, composite gas cylinder, carbon dioxide monitoring
National Category
Other Engineering and Technologies not elsewhere specified
Identifiers
URN: urn:nbn:se:bth-20419ISBN: 978-91-7295-408-3 (print)OAI: oai:DiVA.org:bth-20419DiVA, id: diva2:1470427
Presentation
2020-11-06, Vallhallavägen 1, Karlskrona, 15:00 (English)
Opponent
Supervisors
Funder
Swedish Armed ForcesAvailable from: 2020-09-25 Created: 2020-09-24 Last updated: 2020-10-16Bibliographically approved
List of papers
1. Safety algorithm for predicting PO2 in electronic closed circuit rebreathers
Open this publication in new window or tab >>Safety algorithm for predicting PO2 in electronic closed circuit rebreathers
2016 (English)Other (Other (popular science, discussion, etc.))
National Category
Signal Processing
Identifiers
urn:nbn:se:bth-20481 (URN)
Note

Poster at UHMS Annual Scientific Meeting 2016

Available from: 2020-09-25 Created: 2020-09-25 Last updated: 2020-10-05Bibliographically approved
2. PPO2 sensor authentication for electronic closed circuit rebreathers
Open this publication in new window or tab >>PPO2 sensor authentication for electronic closed circuit rebreathers
2017 (English)Patent (Other (popular science, discussion, etc.))
National Category
Signal Processing
Identifiers
urn:nbn:se:bth-20469 (URN)
Patent
WIPO/PCT WO 2017/212464 A1 (2017-12-14)
Available from: 2020-09-25 Created: 2020-09-25 Last updated: 2023-08-07Bibliographically approved
3. The performance of 'temperature stick' carbon dioxide absorbent monitors in diving rebreathers
Open this publication in new window or tab >>The performance of 'temperature stick' carbon dioxide absorbent monitors in diving rebreathers
Show others...
2019 (English)In: Diving and Hyperbaric Medicine, ISSN 1833-3516, Vol. 49, no 1, p. 48-56Article in journal (Refereed) Published
Abstract [en]

INTRODUCTION: Diving rebreathers use canisters containing soda lime to remove carbon dioxide (CO2) from expired gas. Soda lime has a finite ability to absorb CO₂. Temperature sticks monitor the exothermic reaction between CO₂ and soda lime to predict remaining absorptive capacity. The accuracy of these predictions was investigated in two rebreathers that utilise temperature sticks. METHODS: Inspiration and rEvo rebreathers filled with new soda lime were immersed in water at 19°C and operated on mechanical circuits whose ventilation and CO₂-addition parameters simulated dives involving either moderate exercise (6 MET) throughout (mod-ex), or 90 minutes of 6 MET exercise followed by 2 MET exercise (low-ex) until breakthrough (inspired PCO₂ [PiCO₂] = 1 kPa). Simulated dives were conducted at surface pressure (sea-level) (low-ex: Inspiration, n = 5; rEvo, n = 5; mod-ex: Inspiration, n = 7, rEvo, n = 5) and at 3-6 metres' sea water (msw) depth (mod-ex protocol only: Inspiration, n = 8; rEvo, n = 5). RESULTS: Operated at surface pressure, both rebreathers warned appropriately in four of five low-ex tests but failed to do so in the 12 mod-ex tests. At 3-6 msw depth, warnings preceded breakthrough in 11 of 13 mod-ex tests. The rEvo warned conservatively in all five tests (approximately 60 minutes prior). Inspiration warnings immediately preceded breakthrough in six of eight tests, but were marginally late in one test and 13 minutes late in another. CONCLUSION: When operated at even shallow depth, temperature sticks provided timely warning of significant CO₂ breakthrough in the scenarios examined. They are much less accurate during simulated exercise at surface pressure. Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.

Place, publisher, year, edition, pages
South Pacific Underwater Medicine Society, 2019
Keywords
Equipment, Hypercapnia, Monitoring, Soda lime, Technical diving
National Category
Respiratory Medicine and Allergy
Identifiers
urn:nbn:se:bth-17764 (URN)10.28920/dhm49.1.48-56 (DOI)000463069300008 ()2-s2.0-85062856026 (Scopus ID)
Available from: 2019-04-04 Created: 2019-04-04 Last updated: 2023-08-07Bibliographically approved
4. Permeability properties of a pressure induced compacted polymer liner in gas cylinder
Open this publication in new window or tab >>Permeability properties of a pressure induced compacted polymer liner in gas cylinder
2021 (English)In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 138, no 18, article id 50335Article in journal (Refereed) Published
Abstract [en]

The permeability properties of composite gas cylinders for breathing gas with polymer inner-liner are investigated. The cylinder wall can be described as a composite membrane consisting of two layers. The permeability properties of the cylinder are presented as permeability coefficient and permselectivity. Deviation from the expected gas components might lead to incidents and potentially harmful situations when breathing gas from a compressed gas cylinder. Hence, gas permeability and potential changes in gas composition, must be considered when choosing cylinder materials. Cases of decompression sickness initiated this study. Experimental data show that pressure and oxygen fraction in the gas cylinder drops and that the permeability coefficient varies depending on the inner pressure. Permeability coefficients of 0.62–0.90 Barrer for oxygen and 0.44–0.56 Barrer for nitrogen are measured. Cracks in the inner-liner have caused an accentuated drop in of oxygen fraction and pressure. © 2020 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals LLC.

Place, publisher, year, edition, pages
John Wiley & Sons, 2021
Keywords
composites, copolymers, theory and modeling, thermoplastics
National Category
Textile, Rubber and Polymeric Materials
Identifiers
urn:nbn:se:bth-20479 (URN)10.1002/app.50335 (DOI)000593037300001 ()2-s2.0-85096852865 (Scopus ID)
Note

open access

Available from: 2020-09-25 Created: 2020-09-25 Last updated: 2023-08-07Bibliographically approved

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