GB2549064A

GB2549064A - Oxygen depletion test apparatus and method

Info

Publication number: GB2549064A
Application number: GB1603091.8A
Authority: GB
Inventors: Burke Daniel
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-02-23
Filing date: 2016-02-23
Publication date: 2017-10-11
Anticipated expiration: 2036-02-23
Also published as: GB2549064B; GB201603091D0

Abstract

An oxygen depletion test apparatus 1 comprises a chamber within a housing 3 for reception of an oxygen depleting sample 25, an access opening 4 for loading the chamber, a cover 5 which seals the access opening, and a vacuum measurement device 6 connected to the chamber interior. The vacuum device may be a manometer tube connected to the cover. With the cover removed, a quantity of steel scrap material 25 such as nails, steel, or swarf, is mounted within the chamber, and the cover replaced. Over a time period, the material 25 within the chamber will deplete oxygen thus generating a vacuum or lower pressure within the chamber which is indicated the manometer. The apparatus may be used to demonstrate depletion of oxygen in enclosed spaces, such as on board a ship.

Description

“Oxygen Depletion Test Adi^yMus and Method”

Introduction

The present invention, i& diteSfc towards an oxygen depletion: test apparatus arid method, in particular fer use as an educational aid which Simuiatos iffi®. depletion Of oxygen within enclosed: spies on hoard a ship.

The: general: sense that people have is that most of the dry balk cargoes are; !n everyday use, sometimes as foodstuffs and therefore of benign nature:, and also within fresh water tanks and ballast tanks where the water is used for drinking or for swimming in, and perhaps people are lulled into a Seise Sense of security because of this everyday usage apialfegedly ipnlgn nature of the cargo and tank contents.

It Is nepeaoafy to acutely raise people's awareness feat onee the hatch covers or tank lids are cldsld, the oxygon contained in the space jp immediately befog absorbed by the cargo or due to rusting within.a space. Beathsio: enclosed spaces appear to rpn at a rate of o*-e per day in the shipping industry.

Air contains Id different gases with four main components;

NitrogeOi Oxygen, Argon, and Carbon cfoxide are the main components with seven additional gases of very IdWpphtent. andflye other gaseSi With traoegelemants..

Detection eguipmenf1 is readily available to ascertain the; oxygen level; within an enclosed space at any specific Hhi®, however it is raf® to have continuous moniiteringot' these spaees>

The purpose of the present Ihyentionns to ilpstrafe fc depletion by rusting or absorption into sorap; metal canoes and also to illustrate the speed; at which the oxygen depletion takes place, with a view to Improved safety by making people acutely aware of the oxygen depletion that takes place in such enclosed spaces.

Summary of the Invention &®refe§ to the mventldh, there is provided an oxygen depletion test apparatus

Including: a chamber for reception dif an oxygendepleting sample material the chamber having an access opening for loading the sample material in the champers a courier sealing engagementMth the access opening, and a vacuum fn^ lo an interior of the chamber. iln one embodimentoithe invention, the access opening Is cylindrical and the ceteris a oompiernepiary disc having a circumferential seal for sealing engagement with a Side waif of the access opening when lie cover is mounted in the access opening.

In another 'embodiment,rtheseat;:te resifsently deformabte.

In another embodiment, the volume pf the chamber te adjustable. ih another embodiment, the cover Is slidably engagahie with a side ^ilpflie access; opening for adjustment of the velum® df the chamber in another embodiment,: the chamber comprised a Cylindrical hoysing having an Interior which forms the chamber, the housing having a closed inner end and an open outer end, the qpyer Pelngi engagebie within a lore of the bousing to close the outer ehdl

In another embodiment, the cover Is axially movable through the housing to adjust the yoluroe of the chamberi

In another embodiment, IWheretn: the cover comprises a pair of Overlapping circular plates and the seefccrhprtsesia; resilienfiy deformable ^tielemant^pun^edli^^eein: the plates, said circular plates being movable tQptherihdidbartIdr radiat detormatiori of the seat dement

In another emhqdimeni, a: screw fasfeoerIs minted between: the plates, said screw ladenei: being: operable to fiovdside plafee together and; apart.

In another embedfspepf^ the screwifasfenec is centrally' mounted on the plates,:

In another embodiment, the vacuum .ai'^rtpiSatef.'

In another aspect, the invention: provides a method for rneasuring oxygen depletion in an enclosed spaced, comprising: mounting ;;ap:· oxygen dspief ing sampiemsterial in aiphamber, sealing: tbechamder,; measuring the vacuum generated within an Interior of the chamber due to oxygen depletion w|hifi fie sealedchamber.

The invention will be more clearly understood by the fplkwying description; of some embodiments thereof, glyph by way of example Only, With reference to the: accompanying d· swings, in which:

Rg. 1 is a schematic ifcsimtibn ci an oxygen depletion test apparatus according to the invention,

Flg,; 2 is a table of experimental results using the apparatus of the Invention, and Rig, 3 is a: Schematic ilysfitlbmof time elongation for replacement am

Detailedration of the Preferred Embodiments

Referring fit the: drawings, fears is Illustrate an oxygen depletion lest fgggrgtus according Id fee invention, Indidatsl; lenetaiy by the referenci: numeral ii. The apparatus 1 comprises a chamber 2 In a container or bousing 3, An access opening 4 M a top Of the housing 3 is dosed by a cover I rtlch seals the access opening; sfe A manometer^1 is connected by a flexible tube 7 with a vent p-patiilrii the covers which oOiiifebnicatis with the chamDer 2.

The housing 3 comprises a circular base 10-with -atf o^fedric# aide wail 11, An open upper end -of fee side wail 3 forms the access Opening 4 and fee cover | is formed by a complementary disc haying a circumferentsai seat 12 for sealing engagement with a n inner face 14 of fee side wail 11 when the cover 5 is mounted in the access opening 4. It will be noted that the cover 5 can be moved axially through the housing 3 to. adjust fee volume ofthe chamber 2.

The cover f roompnles; | pafr Of Overlapping circular plates 16, 17 and the seal 12 Csmpnses d seal ring mounted between the plates Id, 17. The plates 16, 17 are movable together and apart for radial deformation of the seal |2. Thus, when fee plated 16, IT move together, the seal 12 deforms moving iradlalty outwardly to sealingiy engage with the inner face 14 of the housing 11. Tpreieese fee cover 5, the plates 16, 17 are moved apart, allowing the seal 12 to coliape Inwardly again:, so the cover | can be readily easily removed from the housing ft.

The plates· 1 β, 17 may conveniently be doonsoted by means of a: screw fastener 2§ comprising a holt; |f centrally: mounted on one piate; "11: end extending through a: central hole In the other plate 17 for edpgerodbf by a look out 22. Art axial through hole extending through the bolt 21 connects with the vent pip 8 to allow communicationbetween fed chamber 2 and manometer 6 through the tube 7.

The manometer 6 may conveniently he formed1 by a length of dear plastic tubing arranged in a U-shape, as shown, and mounted on a supporting board or the like (not shown), The clear plastic tubing is partially filled with water in fee usual way fef^iSte :a.feahcsit>ejir: A scale may be provided on this board. ti CSb, -§8th the cover 5 removed, a quantity of steel scrap malarial 26 such Ss oats, steel, swart: or the fsk% is mounted within the chamber 2. The coyer 5 is Inserted into the access opening 4 at a top of the housing 3 and the plates 16, 1? are moved together by tighfenmq the iock nut 22 on the bolt 21 of the fastener 20. Thus, the seal 1:2: is deformed outwardly to seahngiy engine' w*th the inner side Wall 14- Of the housing 3, Over a time period, the scrap; steel 25 within the chamber 2 will deplete oxygen within the chamber 2, thus generating a vacuiim within the chamber 2, which is indicated on the manometer 6,

If desired:,: the housing 3 could be made of a dear plastibsimafehihor a window might be provided in the side waii 11 to view; the contents of the housing 11 Various stiff plastics containers could be used.

White an adjustable cover 5 has been described, it is also possible to use a fixed cover which might be.hinged on the: Side wail 11, for example, with an appropriate seal between the covermhd the access opening %

While the manometer 6 Is particularly convenient for illustrating the oxygen dipietibn within the chamber 2, .other types, of vacuum measurement devices might be employed in alternative constructions of the apparatus.

The only constituent: of air that is absorbed through : tfee: rusting process is oxygen and tfmmfpm; with the other constituents of air being of an inert nature any reduction in pressure internaiiy In the container will be as a direct result of oxygen depiction due to rusting and will be as reiiabie as any other type of monitoring from an experimental point of view.

Electronic or other constant monitoripgiwould necessitate the extraction of a sample of the contents and would therefore decrease the oxygen levels causing unreliable results.

The experiments should be .parried out psingan air tight container to prevent any ai' from outside leaking -n and distorting fhd ypsijym readings. The container should be of adegtiile strength so as to pmveht distortion due to the partial vacuum ereetedi by the oxygen depletion. ideaify the experiment should be commenced at the beginning of an enclosed spaces course. During the course, the progress of the vacuum can be observed and act as an added heightening o-r awareness of the dangers involved. This will be extremely relevant when the minimum permissible oxygen level is reached and the related time involved.

Something seen:wlir|^5.^!i^'bared: for fdngpr than something said. it is the speed of the oxygen depletion that should shock the course participants or at the very least help to raise their awareness of the unseen dangers within enclosed spaces: and other spaces linked for access purposes to the cargo spaces. Whilst it would be ideal after an appropriate pressure drop (Illustrating that the oxygen level has reduced) to be able to ascertain the oxygen level using an oxygen meter to cross-check the theory of the experiment, however, as the air space is relatively small in the experiment container compared to a cargo hold or tank, any monitoring by sampling that would further use up the oxygen level during the measuring process will give inaccurate results.

Dalton’s Law of Partial Pressure:

For a mixture of gases in any container, the total pressure exerted is the sum of the pressures that each gas would exert if it were alone in that container.

When the total pressure of dry air is 100 kPa or one fear, the partial pressures; of each of Its components (in kPa) are numerically equal to the percentage of that component.

Normal Air containing some moisture is composed of 15 different gases however the following are the largest constituents:; %: Partial Pressure

Oxygen (02) 20.9%, 2Q.9kPa

Nitrogen (Nj) 78.1%, 73.1kPa

Argon {Ar) 0.07%, 0.97kPa

Carbon Dioxide (C02) 0.05%, G,Q6kPa wateniH^O} :ii.28%, tmm: ffta standard atmosphere Is a unit of pressure equal to 101.325 kPa or 14.098 psi. This is equivalent to the pressure exerted fey a column of 763,2 millimetres of Mercury (Hg), or 30.047 inches of Mercury (Hg.

With mercury having a density of 13.5338 these figures translate into a column of water giving 10285 5 mm of Water or 404.942 inches of Water.

The Partial Pressure of the Oxygen would then fee represented by 2188 J rnm idf water or 85.39 Inches of water. (21 % of an atmosphere)

Theory· of Tfep e^pe|is©nt:·

Assuming that the pressure of dry air is TOO kPs, ami if all the Oxygen were used up in corrosion or absorption, the pressure in the container would be the atmospheric pressure reduced by the Partial Pressure of Oxygen being 20.9kPa. therefore the pressure would be 79.1kP&>

For the purpose of the measurements, the oxygen percentage is assumed to fed; jf.. I /v*

In the experiment it is assumed that there would be some moisture therefore the atmospheric pressure would be 101 325 kpa..

To illustrate this, on a mmmmel&r using water a& the indicating ΙιφΜ* tfre partial· pressure would be reprmaMed by a column of water as sei out M the MMmmg tables:

It is important to note that the experiments were carried out under ideal eondiionsp and will differ from the actual rate of depletion in cargo holds and tanks. This is dealt with later.

However the purpose of these results will be Ip highlight: the problems and particularly the speed of the oxygen depletion Involved as dMhot to a mathematical evaluation, and this should raise a person’s awareness of The dangers involved in enclosed spaces.

PsMng an ongoing rusting process;

A number 0Γ were baffled out using apparatus of the invention, the; results:of; which are shown in the Appendices hereto.

Experiment Mo.3 used a containerly with, swarf., wire brushed steel effects and 20kg of clean nails giving an almost ®iif oentiihaf IS., This would ;realisii©d!iy be much doser to simulating the pargo hdil όοηΙόΡίδιίιΛόρ: carrying scrap Steel:cargo! or fhaf of a fealiast tank. The contents were ||tl·moist after cieart||ng wMn the which again could probably replicate loading cbndltfehO.

Expe®rpettt 4 used a container 3. in order to replicate Experiment 3, with the same swarf, wire brushed steel offcuts and 20kg of dean nails giving an almost full container as in Experiment 3. The contents were well vent Ha ted using a blower and a little wafer spray was: used to moisten the contents after the ventilation. There was sufficient space or permeability for air to |e distributed throughout the simulated cargo. This would realistically be reasona bly close to simulating the cargo hold conterits when carrying scrap sfeei cargo. The contents were still moist after cleansing when the container was closed.. this moistness oboldipmbibly replicate folding conditions,

Experiment;! S was again necessary in order to repiicate;: or further prove Experiments 3 and 4, and this again proved what had already bepn fgund during Experiment# 3 & 4 that the rapid reduction ot oxygen level is a sipftioaffttfaotpr:; A water sgraypn the contents:mm:!ogt used in Experiment: 5.

Experiment 8 was used as a furthirmeans cf proving the results ft&m Experiments 3:, Aond 5, and also 10 enableiMMip: personnel to observe the: rate of change of the results as tney^progressed!

Experiment 12 This experiment was carried out to enable a sequence of photographs to be taken at one minute Interval over a period of five hours that will act as a record of the experiment

Experiments 1 to 11 and Experiments 13 to 1§ were carried out to test the behaviour of a smaller and more oompact version of the apparatus 1.

These experiments utilised a :smai transportsble apparatus I with; approximately M kg of Nails to simulate a scrap metal cargo. The apparatus 1: is made from a 150mm plastic sewer pipe with one sealed end and the other end with a screw on pap apd: seal, ip addition a pipe test plug was used that wouid enable a reduction of the free: air spade within the containment to simulate a full or pari cargo. in addition the manometer 6 was of a smaller range fried the full 2.4 metre Manometer, however it would :he eapabierof representing oxygen depletion down to a level of 11%. The entire lit^ wpuld he ppntaihad within thecontainer 3 and could he eassly carried. Trie kit would require ah assembly time ofabout 20 minutes,

Comments;:

Note the comments made above re preparation. All surfaces to be free of oil / gfoase and surfaces of steel off-cute to be wire brushed or ideally grit; blasted to remove any coating. New: nails will have a coating of milhsoaiefcil and need: Cleaning In order to be efiecltye.

Constant temperature is advised as large temperature swings will cause the air in the container to expand or contract., thereby slightly raising or lowering the internal pressure. Ensure that a!l components have stabilised at room temperature prior to comfnenci ng experiment. insure thetitrieimshdrrieiir is standing: vertically: and that the iwater level id centred in trie working section of the manometer prior to: start of experiment as trio water movement within the manometer is substantial,

Spadingt sriould be taken at regular Intervals preferably on an hourly basis from an accuracy; point of view.

PartteuiPr empriasis: is to be placed on the first few hours of the experiment iron) an impact point of iew pariicuiariy during the time frame within the safe oxygen levels.

The time taken for the oxygen: level to drop to dangerouslevels will be important sn getting trie g-ressage across fo studoo& oud to crew members. (Using Larger Apparatus 1]

Experiment 3: The experiment proved very satisfactory in that the container 3. had sufficient strength to withstand any flexing or deforming in addition to being airtight, and therefore valid results could be expected. M, restart of the experiment about 50 minutes after commencement where it was necessary to ©pen the hose connection thereby causing; a 'top uc of air into the contether 3 which slowed down the initial spaed reabtiOri but did not invalidate the general: thrust of the findings as: the msting: process is continuous and wm riot overly disturbed*

The results proved to be quite startling in that the speed of the more rapid than had been anticipated. /L reduction of the oxygen level of 0.83% after just two and a half hours was not expected and within five hours of the experiment commencement the Oxygen level had dropped below the minimum permissible level of 19.5% and into the danger zone and then continued on a very steady rate of oxygen percentage reduction thereafter. This is reflected in very close monitoring of the rate of change after the initial observation and over the ensuing hours however monitoring; then became less frequent and settled down to an hourly observation thereafter.

There was a very steady rate of change of oxygen level during the experiment averaging approximately 25 mm of water vacuum on the manometer per hour. During day 2 of the experiment there was a slight reduction in the rate of change however this could have;been due to an increase in tire ambient temperature during the middle of the day.

The extremely rapid: reduction of the oxygen level within five hours of the commehcement of the experiment to below the safe level must be utilised in. training courses as a shock tactic that should make participants take notice and understand: just how dangerous enclosed spaces are. This time frame will be s u perseded by further experirne nfs.

Whilst preparation of the experiment does take some effort before an enclosed spaces course iebmfheriies, the effect of being able to illustrate end observe the

Clangers as ihe^ happen would far outweigh the effort end give huge value addedTp the impact it should have pn the participants.

The experiment will be replicated as soon as possible after the conclusion of Experiment 3 without any further cleansing or preparation of the container contents so that«; conclusion pan be reached that rusting is both rapid and a pintinuous process. Ventilation of the space will occur using arrfhppwef that woUSb: cause circulation of air to clear out any inert gases that

Experiment 4: The experiment: was vital in order:: to IrepCate or further prove Experiment irendi this proved to be even:more etarllhg in that the results were far more rapid than Experiment 3. The oxygen level had dropped below the safe limit Within 2 hours and had reached an oxygen level of 1i:3&f§ at this early stage. Within 4§ hours the level had dropped into She Black; lone |Qxygen level below 6%.)

The speed of rusting in Exp, 4 may be due to the fact that the surface of the nails may have been sufficiently broken down id as to permit mans rapid oxidation, A slowing of the progress occurred at 4.90% and observation of the contents rnay pxptai n this: slowing down, fiowever, again suiloient information has been gathered to enable me to terminate the experiment at this stage and to proceed further with Experiment 5, It is felt that it may be; necessary to wash out the contents in addition to ventilating the contents again prior to recommencing Exp. 5.

Experiment 5 was again necessary in order to replicate or further prove Experiments 3 and 4, and; this proved what had already been: found during Experiments 3 & 4 that the rapid reduction of oxygen level is a significant factor that Administrations. Companies, Crew members, and Teaching and Training Establishments should highlight;;Id trying to prevent deaths in oases of entry Into ehdldsed spaces. A water spray on the contents was notused in Experiment 5.

The oxygen leyei had dropped very close to the safe smlt m lust over 2 hours and: had reached an oxygen level of 19,09% in 3 hours.

Exiteidmeni i; was necessary In order to further prove Experiments % 4 and 5, and alao to:allow observation by NMCI person net who intend to replicate the experiment during: enclosed spaces courses, and this again proved what had already bean found during Experiments 3, 4 and 5. k water spray 'pniihf^ppntents was used in Experiment 6,

The oxygen level had dropped below thetSSfe limit in just 2 hours and hpd reached: an oxygen leVetof 19.41% in this 11A The: oxygen level dropped te: Sate: In SS tours. The steel swarf was omitted: fh: this cam the steel off-cuts were wire brpshpdyand the nails were cleaned using dry plastering sand in a rofafeg drum tp· give Clean surfaces for rusting.

The relulis: ate consistent with the previous experiments except that this was the only experiment to reach a zero oxygen: level, probably due to cleaning of the contents allowing fora mote aggressive oxidation to take place.

Experiment 12 This experiment was carried out to enable a sequence of photographs to he taken at one minute Interval over a: period of five hours that will : act as a record of the experiment.

Experiment Observations fUsmg Smaller Apparatus 1)

These experiments utilised a small transportable apparatus 1 with approximately 10 kg of Nails to simulate a Scrap metal cargo. The apparatus Is mad© from a 150mm plastic sewer pip© wfe poe seated end and the other end with a screw on cap and seal, In addition a pipe test plug:was used that, would enable a reduction of the free air spaa© within the containment to simulate a full or part cargo.

In addition the manometer would be of a smaller range than the full 2,4 metre Manometer, however it would be capable of representing oxygeh depletion down to a level of 11%. The entire kit would be contained within the container: and epuid b© ©asTy carried, The kit would require an assembly time of about 20 minutes,

Sss^rimertt 7 showed a very quick reaction with the oxygen level dropping betas? the 19.5% in a iiltle over an hour, and dropped to 5.18% in just 28 hours. a greater air space was given in the experiment and it showed a four hour period was needed to reach the 19.5% level, however it reached 9:7¾ in 47 hours,

Expert meet 9 was carried out as a trial to enable a series of photographs takers on a timer system that would show the rate Oh Change of the oxygen level within the container over a perfed of throe hours. The photographs session ceased when the water levels has gone outside the camera focus and: this was after 3 hours. No physical measurements were taken during this time. Physical measurements were liken after- 5 & 8 hours. The experiment was stopped after 8 hoars when the oxygen level had reached 16.06%.

Experiment 10 was carried out to enable a senes of photographs taken on a timer system ilpf wpyid show the rate of change ofthe oxygen level within the container over a pedod of three hours, This sequence of photos couid then be shown hi a video clip to act as an alternative mothod df raMhg awareness.

Experiment 11 An additional sir space of SOmrn or approximately 12% was added; to the previous positioning:; of the test plug. Within one hour the 19.5% oxygen level had been reached. The experiment: was concluded after 8.75 hours as the mid; range manometer limit; had; been reached:

Experiments i;i to 15 were carried out to further test the behaviour of the smaller and mom compact version of the experiment.

Experiment 16: This additional experiment was commenced at 18.20 hours on the 13ih February at a; tempeptup of 9 degrees C in order to fort her observe the oxygen depietion at cooler temperatures. This experiment foilowed on immediately from Experiment 15 and no cleaning was done on the nails the container was refreshed by using the air blower with the contents still in there. The nails were silghtiy damp when the experiment commenced from the previous experiment. The seal was pressed down against the cargo so that there was very little free asr at the top of the containment.

The swiftness of reaction in this case was spectacular with the oxygen level reaching the minimum permissible level in just 15 minutes The nails were used for thelrsfTithe: and :®sepeh!i:Swere guile dean.

Whilst ;t Is proved under experimental conditions that after appfoxlmsfely $ hours or less ifo oxygen level has definitively reduced to below the safe levels* it mu#f he stressed: that trie only conclusion that oho he reached is that if is unsafe at any time fo: enter m enclosed space, and in addition any access way to the hold such aS ih the:1 forecastle area must also be suspected as being devoid of oxygen, Entry cars only be;: undertaken: hy taking the appropriate precautions and thorough yentilation of the space.

This rapid reduction of oxygen level is a significant factor that Administrations, Oompanies, Crew members., and Teaching and Training Establishments should tniM tirifQ to prevent deaths In cases of entry into enclosed spaces. tp the larger type of container the permeability of the space was calculated to be 76% with steel ©icuts; and nails. The steel offcuts per kilogram have a much gmaiier surface area than the nails !n the smaller type of container (Mini version) the permeability was calculated at 03% with naiis only,: This will account for the faster reaction of the Mini version due to a greater surface area of material. The greater the air space the slower the rate of oxyganidapiation.

The main advantage: of the Mini version is that it Is much easier to adjust the amount of free air space above the “cargo* by the use: of the test plug as the sealing; mechanism: as distinct from the screw cap in the keg version. Ih addition the amount of sirnulaiad; mtg% can hid: be varied to give comparisons. The emptying of the Mini versiph f|f οΙβ9^Μ·'1:·ΙΙ·ΙΡ: sfrnpler the larger type of container.

Conclusion;

The almost identical replication of the experiments proves conclusively that this can act as a powerful message for course participants to actually see how rapidly the oxygen depletion Is taking place.

Taw snocK tactic of seeing the depletion of the oxygen content to· below the safe level within 2 hours (keg container) wj! be a message that will be remembered. it is very necessary to acutely raise people’s awareness that once the hatch covers or tank lids are closed, that the oxygen contained within the space is immediately being absorbed by the cargo or due to rusting within a space, and that an enclosed space must at all times assumed to be unsafe.

It is hoped that these experimental findihgs will help to raise this awareness ind result in a reduction of fatalities.

The amount of free air space within the container wiltaffect the depletion rate. The more air the slower the reaction. Temperature seerhs to affeci the rate of depletion and in warm conditions the rate of depletion seems to be greater than in cold conditions.

It must he stressed that any adjacent space that has linkage for access purposes to the cargo spaces must be considered as an extension of the cargo spaces and may suffer from oxygon depletion through leakage Into the cargo hold. tsofnparison of Experiment to a hold or tank situation;

If the experiment results were to be compared to a cargo hold or tank situation my theory is as follows; It is assumed that the rate of rusting would continue at the same rate as in the experiment, and that no forced ventilation is used.

The replacement of the used oxygen by new air top up would be a griduai process however It is simpler fp assume in the following fashion; oxygen within the space were to be consu med then a; ffisl top up of E&O# of the volume would be drawn in to replace the oxygenccnsumed Ibereby adding a further 20.9% of the time to dp resuits {seeRg,3}.

In cue course as this additional top up is again consumed a further fresh charge of 20.9% of the id si top up volume will im added giving an added 4.41% of time arid thereafter top ups of 2thS% of a diminishing amount giving 0.0093%. plus 0,0019%, plus 0 0004%, plus 0.000086% etc. will give an estimated elongation of the time factor by 26.58%. .OriginalContainment·: 1% Refill 2!i<! 3* etc.

Chain lockers will closely parallel the experiment findings due to the amount dt surface adea of the chain, dallast tanks will have a slower rate of oxygen depletion however once the ©xvgen has been depleted it thereafter remains at 0% oxygen for months on end until entry is required and ventilation fakes place.

The. 'following appendic&B gim additional information on the experiment findings:

Appendix V Experiments on Scrap Meta/ cargoes (5 Experiments) using a sturdy container with 20kg of nails and steel-off cuts.

Appendix 2: Experiments on Scrap Meiai cargoes (9 Experiments) using a small transportable unit with iOkg of nails,.

Appendix 3: Description of Experiment Equipment

Oxygen Depletion Experiment

Appeaitx 1

To Simulate: The Depletion of Oxygen within enclosed spaces cm hoard ship,

Experimeiits on; Scrap Melal Cargoes (5 Experiments) using a sturdy container with 20kg of nails and steel-offcuts.

To Simulate: The Depletion of Oxygen within enclosed spaces on board ship.

Experiments on: Scrap Metal Cargoes (9 Experiments) using a small transportable unit with 10kg of nails,

Oxygen Depletion Experiment

Appendix 3.

To Simulate; The Depletion of Oxygen within enclosed spaces on hoard ship.

Description of experimentequipment;

Keg type is a strong plastic beer keg with screw on air tight lid:

This ski has been modified to include a tank connection that connects to a 2.4 metre high manometer or water gauge. This manometer ss made from clear plastic hose on a timber hacking and the manometer is graduated to illustrate the level of oxygen depletion taking place. The connection from the container to the hose is by way of copper pipe to the tank connection

Transportable type is made from if plas tic pipe with test pl ug lor sealing;

The transportable type is made from a portion of b” plastic sewer pipe with a plastic cap cemented into place to dose one end. The container is sealed for use by using a sewer pipe test plug that connects to a 40“ manometer or water gauge. This manometer u; made from clear plastic hose on a timber backing, and the manometer Is graduated to illustrate the level of oxygen depletion taking place. The connection from the container to the hose is by way of copper pipe to the tank connection

Claims

Claims |. An oxygen depletion iestiapparatus 'indiudihg: a Phamfeshfbf reception ofane^yg^^ mitedai, the chamber :¾¾ iih; access opening for loading the sample material iri the clamber, a cover for sealing engagement with the access opening, and avacuum measurement device connected to an snfenor oi ihe chamber. f, The apparatus a| claimed in claim 1, wherein tie access opening is cplndhcai and the cover Is a cimpiemeofary disc having a circumferential sea! for sealing engagepeet wlfh: a side wall of theacoess opening when the cover Is mounted in tie access opening.
3, The apparatus as claimed in claim 2f wheretilheseal Is fdsilieritiy deformable. 4 The apparatus as claimed in any preceding; Claim, therein the volam© of fie chamber is adjustable
5. The apparatus as Claimed in any preceding claim, wheiein the cover is slidably engagable with a side wall of the access e^aning for adjustment of the volume of the chamber.
6, The apparatus as Claimed in any preceding claim, wherein the chamber compnses a cytedrieai housing having an Intehorwhjeh forms the chamber, the housing having a closed inner end and an open outer end, the cover being engagaile within a bore: of its© housing to close the outer end . 7» The apparatus as claimed In claim S, wherein the cover is axially movable through the housing to adjust the volume of the chamber.
8. The appretM as daaned in any one of ejialbp 2 : to 7, wherein;, tfm cover comprises; 1, pair of ©verfapping circular plates and the seal oompnips f seal element mounted between the plates, paid cirquiar plates being movaill together and; apart for radial: deformation of the seal element. 9. fbe apparatus as claimed in claim 8, wherein a screw fastener is mounted between the plates, said screw fastener being operable to move the plates together and apart.
10. Tha apparatus as claimed In -dairy* 9, wherein the screw; fastener is centrally :fh&iihi«d on the plates.
11. The apparatus as claimed rh any preceding claim, wherein the vacuum measurement device comprises a manometer: ill, The oxygen depletion test apparatus substantially as hemintjefore described with -reference %the accompanying drawings. I E A method for measuring oxygen depletion in awendipsed spaoecb comprising; iap^^iyiipiefty sample material in a chamber; Sealing the chamber, measuring the vacuum generated within an Inferior of the chamber due to oxygen depletion within the sealed; chamber,: