Development of the New Diving Apparatus Klos R/% Majchrzycka A

Development of the new diving apparatus

Klos R/% Majchrzycka A .^, Poleszak S/^

^ The Naval Academy of Gdynia, 8 1-9 19 Gdynia 19, Smidowicza 71,

Poland, E-mail:klos@amw. gdynia.pl ^Technical University ofSzczecin,70-310 Szczecin, Piastow 19, Poland,

E-mail :anhanmaj@safona. tuniv. szczecin.pl

Abstract: The paper discusses implementation research of the diving apparatus. At the first stage of research, the tests were performed with the use of the breathing simulator and after satisfactory completion of unmanned tests, hyperbaric manned tests were carried out.

1 Introduction

Implementation research of the new types of the breathing apparatus is aimed at: • elaboration of the brief foredesign, • evaluation of the brief foredesign: • in unmanned laboratory tests

• in manned normobaric laboratory tests, • in manned hyperbaric laboratory tests, • in the tests at the work site, • engineering supervision of the diving apparatus.

Above mentioned activites must be a part of implementation research of the diving system that includes: • decompression system, • systems of decompression protection,

• the diver's transportation system, • the breathing mixture supply systems. In order to ensure safety during diving operations simultaneous implementation research of the decompression system and other subsystems is necessary.

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Elaboration of the diving apparatus brief foredesign should be preceeded with the answer concerning the scope of diving system and the tasks of the diving apparatus.

2 Elaboration of the brief foredesign

Diving operations can be divided with respect to the depth into: • shallow diving (7,5-20m), • medium depth diving (30-40m), • great depth diving (50-60m),

• typical large depth diving (up to 200m), • typical very large depth diving (up to 300m), • very large depth diving (up to 350-470m),

• very large depth experimental diving (up to 500-600m), • very large depth experimental breaking diving record (record 701m). According to the diving tasks diving operations are subdived into: • recreational diving: mainly air diving at the shallow depth, decompression

procedures are standarized, • sport diving: usually is a record breaking diving without support from the diving base. In sport the divers usually use the mixed-gas diving air apparatuses, that have been adapted to these purposes. Special individual decompression treatment procedures are being elaborated for each of diving

operation. • commercial diving: covers a wide scope of the diving depth, this diving operation takes an advantage of the great number of standarized diving technologies. As a rule, each diving company has their own standards providing the large number of emergency situations.

• military diving: • operational combat diving with the use of oxygen diving apparatus, • technical diving with the use of the special features diving apparatuses (reduction of magnetic field, semiclosed circuit),

• rescue diving for different tasks even down to the large depth in saturation and beyond saturation zone, special decompression treatment procedures are often used. • rescue diving: the same as military rescue diving but the only difference is

in the object and individual decompression treatment procedures.

A number of division criteria for diving operations have been proposed. Some authors have made an attempt to put in order [7] diving operations but experience based on a wide scope of operations indicates that effective underwater activity usually needs to employ the unique diving system adjusted only to special tasks [1]. Elaboration of the diving apparatus brief foredesign should take into consideration all the functions of the diving apparatus in the diving system. The functions of the diving apparatus in diving system are focused on:

• basic function concerning the gas supply to the diver during routine work of diving system. In order to perform that function the diving apparatus can operate as self contained (scuba) apparatus or tethered i.e. dependency

linked to a source of the breathing gas, • bail out function of the diving apparatus relies on its use at the moment of hazard while the apparatus failures (failure of basic gas supply, failure of external gas supply or regeneration systems). In order to enable immediate

use, the apparatus should be accessible to the diver i.e. attached and connected at the place that enables easy access. Bail-out apparatuses are usually short functioning self-contained apparatuses that enable the diver to escape from the work site to the diving bell or rescue submersible.

• emergency function of the apparatus relies on the long lasting supply of the diver in case of the diving system failure (while the diving bell or underwater vehicle is lost or immobilised). That function enables to maintain the diver at the extreme circumstances, but as the rule it does not let him work.

In order to elaborate the brief foredesign of the breathing apparatus it is necessary to take into consideration human factors, as well. Some parameters concerning human factors are available in the literature but most of them are usually determined in experimental studies. At this stage of research often the mathematical simulation of the diving apparatus functioning is performed. The simulation is based on the mathematical models of ventilation space and decompression treatment (particularly at designing of the special diving apparatus). In order to determine the probability of the diving apparatus failure and reliability parameters, mathematical modelling is performed [3,4]. As a rule, the procedures that have been mentioned above are not available in the literature. However, there are some companies publishing the final consequences and general information concerning research. For these reasons it is impossible to take full advantage of research that has been carried out earlier.

3 Verification of the brief foredesign in unmanned laboratory tests

This stage of research includes an experimental verification of assumptions and models accepted at elaboration of brief foredesign. Satisfactory results of this research stage enable the beginning of manned laboratory tests. The following basic parameters are being investigated in unmanned laboratory tests:

• respiratory parameters: positive-pressure breathing, negative- pressure breathing, respiratory work, changes in respiratory resistance due to hydrostatic influences , protection time of the diving apparatus, • stability parameters: (mass of the diving apparatus, mass distribution and displacement elements, apparatus buoyancy, bending moments while centre

of buoyancy does not cover the centre of diving apparatus gravity, head resistance) • producibility parameters: dimensions and mass of the diving apparatus elements , the level of generated noise and magnetic field, amount of gas

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venting to water, resistance to corrosion and mechanical stroke, time of protective activity related to wear margin of the breathing gas and absorption of carbon dioxide. • ergonomic parameters: valves accessibility and handling comfort, elimination of mistakes at valve handling, facility of manometers

observation, facility of communication, mask visibility, fit and form, selection of materials. • fatigue and reliability parameters (resistance of the diving apparatus harness configuration to damage while immersing to water, resistance to corrosion

and fire with the respect to the high percentage oxygen mixture, valve resistance to handling and resistance of breathing regulator to freezing, strength of gas cylinders, • work parameters of constructional elements of the utmost importance and

the diving apparatus (i.e. investigation of: the regeneration system and output of breathing regulator or entrance nozzle, measuring elements, investigation of the breathing gas contamination , investigation of the dead space ventilation and investigation of the inspired gas composition at fixed emission parameters of carbon dioxide).

Fig.l and Fig.2 present the laboratory sets for the unmanned tests of the diving apparatus that have been built in the hyperbaric laboratory, of The Naval Academy of Gdynia.

Fig. 1: Laboratory set for research of the diving apparatus [photo: The Naval Academy of Gdynia]

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The hyperbaric laboratory of The Naval Academy of Gdynia is the accredited testing laboratory equipped with laboratory sets that enable to carry out an experimental investigations of the diving apparatus prototypes for different tasks. Successful implementation of the safe diving systems should be preceeded with multistage laboratory tests.

4 Normobaric manned laboratory verification of the brief foredesign

This part of research can be carried out in two stages: without immersion and at shallow immersion. The procedure of normobaric laboratory verification of the diving apparatus and respiratory systems for the deep diving purposes is very difficult because they gain their top effectivity at a certain depth. Normobaric testing of the semiclosed diving apparatus of the constant gas flow is usually carried out with the use of breathing gas of the higher oxygen percentage.

Fig. 2: Laboratory set ,,breathing machine" for investigation of the resistance and respiratory work [photo:The Naval Academy of Gdynia]

Parameters of the special diving apparatus that are being investigated: dead space with the limited gas exchange, the composition of the inspired gas, cumulative contamination of the breathing gas, regeneration system functioning, ergonomy, leak tightness. The first stage of research includes diver's exercise on a cycloergometer while respiration is from the unloaded apparatus. Medical

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examination of the divers is essential for the beginning of the experiments. It enables to control the activity level, which is as a matter of fact lower than in water. Each test of the diving apparatus is preceeded by examination of the diver at the same work loads as during the tests of the diving apparatus. Tests of the diving apparatus are carried out while the diver exercises on a cycloergometer.

The range of research tests includes: investigation of ventilation (the composition of inspired and expired gas as well as the composition of the gas in the alleged dead space, gas flow), the work temperatures ( inside scrubber, of inspired and expired gas, inside the respiratory volume), investigation of the regeneration systems (the protective time of scrubber functioning, humidity and the temperature effect on the scrubber functioning, packing resistance to ventilation changes). The next stage of normobaric research is, as a rule, carried out in immersion at the small depth, often in the shallow basin. Simulator of swimming is the most convenient but very expensive device that enables to fix the diver's work load [6]. Simulator keeps the subject stationary and gives him possibility of careful monitoring the diving apparatus and medical parameters. In case of the lack the of simulator, the tests are carried out by the other means. The next stage of the diving apparatus research relies on investigations of the diver swimming at certain distances and fixed work load. In order to determine the composition of inspired and expired gas measurements are carried out periodically, while the diver works and rests. Often telemetric monitoring of the oxygen partial pressure and medical monitoring of the diver are simultaneously carried out. Unfortunately, particulars concerning that stage of research are rarely given in the literature. Laboratory unmanned verification of the brief foredesign and satisfactory final tests of the diving apparatus are fundamental for the further implementation investigations.

5 Hyperbaric laboratory manned verification of the brief foredesign

Hyperbaric laboratory manned tests of the brief foredesign are aimed at verification of the decompression assumptions, concerning the composition of inspired gas and taking into consideration dead space of the breathing apparatus. Investigations should be carried out and elaborated statistically for all predicted possible situations i.e. emergency. Unfortunately particulars concerning the safety of decompression are not given [8] in the literature. However, Watch [9] reported that typical accident rate that is accepted by safe decompression system should be less than 0.1-0.01%. Decompression accident rate is defined as the ratio of the number decompression incidents that have been documented to the total number of decompression treatments. Most often there is no information concerning means and procedures of decompression tests. It seems that information concerning the details of decompression research (laboratory hyperbaric tests, implementation or at the work site) is not of the utmost importance but in reality such statement can not be forgiven. Most of the hyperbaric manned tests are performed in land- based hyperbaric facilities for biomedical and diving research. Fig. 3 presents the hyperbaric land-based diving

complex with ,,wet pot". Fig.4 presents the hyperbaric laboratory set for research of the diving apparatus for different tasks

Fig.3: The land-based hyperbaric diving complex DGKN-120 at the [photo:

The Naval Academy of Gdynia]

Details concerning the diving complex will be presented at the Conference. The scope of manned hyperbaric experiments is almost the same as the one of normobaric tests. At the first stage tests are carried out only under pressure, without immersion. Tests are performed on the cycloergometer (fixed workload) placed inside the hyperbaric diving complex. The second stage of the experiments is performed in ,,wet pot", where the diver is immersed. Immersion tests include measurement of the diver's activity level and investigation of the diving system at different temperatures. Usually at that stage of research there are two divers participating in experiment; an experimental diver and attendant diver taking advantage of the another checked diving technology. More that once during experiments it is necessary to exchange the attendant divers. It occurs, as a rule directly before or after decompression. The attendant divers excused from their duty should be exposed to decompression treatment in the separate compartments of the diving facility. For these reasons, testing of the new diving systems and diving apparatus should be carried out in the hyperbaric complex that consists of several compartments.

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Manned testing of the diving apparatus involves also complex monitoring of the diver's biomedical parameters i.e. heart rate, blood pressure, respiratory rate etc.

Fig.4: The hyperbaric laboratory set inside the hyperbaric facility DGKN-120 for investigation of the diving apparatus [photo:The Naval Academy of Gdynia].

Fig. 5 shows the diver during testing of the apparatus and simultaneous complex monitoring of biomedical parameters. Successful completion of the hyperbaric laboratory manned tests enable to start investigations of the diving apparatus at the work site.

6 Tests of the diving apparatus at the work site

That part of the diving apparatus research is aimed at verification of the brief foredesign at the work site. It is usually combined with the diver's training.

That stage of research includes also: • investigations of the storage requirements, preparation and exploitation procedures (regeneration systems resistance to vessel vibration, the diving apparatus resistance to high humidity storage, scrubber cartridge stability

and its grinding resistance to vessel vibration and high air humidity etc.), • organization of diving: preparation and storage of the breathing gases and scrubber cartridges, underwater voice communication, decompression systems, safety during diving operations, transportation of the divers under pressure in case of environmental accidents, mobility, emergency, rescue

situations.

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Successful completion of research at the work site enables to implement the new diving apparatus to the practical use in the diving systems. Nevertheless, engineering supervision is still the essential requirement for exploitation of some complicated diving systems.

Fig.5: The diver testing the new diving apparatus [photo: The Naval Academy of Gdynia]

7 Conclusions

• Research of the diving apparatus and diving systems have been performed for several years [3,4] in the hyperbaric centre of The Naval Academy of

Gdynia, • In order to implement the new diving apparatus for different tasks, the diving experiments have been carried out according to the presented sequence of investigations with special focus on the diver's safety,

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• Satisfactory completion of laboratory and field tests enabled to develop and implement the following diving systems to the practical use :

• semiclosed-circuit diving apparatus, • mixed gas (helium-oxygen-nitrogen) deep diving system beyond the saturation zone, • mixed-gas (helium-oxygen-nitrogen) saturation diving,

• mixed- gas (oxygen-nitrogen) operational diving system.

References

1. B0e, J. ,Hartnung,K.H.,: Employment of the Polycom 101 gas mixing unit for divers in major project in Norway, Drdger Review 51, pp.26-28, April 1983 2. Jastrz^bski, T., Qualitative analysis of pressure hull reliability of a deep

submersible: Ill-rd Symposiuum on Saturation Diving-Technical Problems., The Naval Academy of Gdynia, Poland, 1991,pp. 123-132 3. Klos ,R.: Ventilation of respiratory space in semiclosed diving apparatus of the constsnt gas flow: Ergonomy, 18,1996, pp.49-58. 4. Klos ,R.: An introduction to theory and research of semiclosed diving

appararus of the constant gas flow. Report of The Naval Academy of Gdynia, Poland, 1992. 5. Stone, W.C.,: Designing a redundant life-support system, AquaCorps 12, 1995,pp.29-34.

6. Sterba, J., A.,: Oxygen consumption during underwater fin swimming wearing dry suit: Navy Experimental Diving Unit: NEDU Report, Panama City, 1990, pp. 11-90. 7. The five methods for professional diving. Communicat Dragerwerk AG Ltibeck, October 1987. 8. Vann, R.D.,: Oxygen exposure management: AquaCorps 7, 1993,

pp.54-59. 9. Watch your language: AquaCorps, 2, 1990, p.3. 10. Zwingelberg, K.M., Shwartz H.J.C.: Fofth manned evaluation of the Exl4Modl underwater breathing apparatus: Navy Experimental Diving y, 1989.