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HAZARDSOF
INERT GASES
IGC Doc 44/00/EReplaces IGC Doc 44/90/E
EUROPEAN INDUSTRIAL GASES ASSOCIATION
AVENUE DES ARTS 3-5 • B – 1210 BRUSSELSTel : +32 2 217 70 98 • Fax : +32 2 219 85 14
E-mail : [email protected] • Internet : http://www.eiga.org
EIGA 2000 - EIGA grants permission to reproduce this publication provided the Association is acknowledged as the source
EUROPEAN INDUSTRIAL GASES ASSOCIATIONAvenue des Arts 3-5 B 1210 Brussels Tel +32 2 217 70 98 Fax +32 2 219 85 14
E-mail: [email protected] Internet: http://www.eiga.org
IGC Doc 44/00/E
HAZARDSOF
INERT GASES
Prepared by: SAG 1990
Reviewed by: SAG 1999
Disclaimer of warrantyAll technical publications of EIGA or under EIGA's name, including Codes of practice, Safety procedures and any other technicalinformation contained in such publications were obtained from sources believed to be reliable and are based on technicalinformation and experience currently available from members of EIGA and others at the date of their issuance.
While EIGA recommends reference to or use of its publications by its members, such reference to or use of EIGA's publications byits members or third parties are purely voluntary and not binding.
Therefore, EIGA or its members make no guarantee of the results and assume no liability or responsibility in connection with thereference to or use of information or suggestions contained in EIGA's publications.
EIGA has no control whatsoever as regards, performance or non performance, misinterpretation, proper or improper use of anyinformation or suggestions contained in EIGA's publications by any person or entity (including EIGA members) and EIGA expresslydisclaims any liability in connection thereto.
EIGA's publications are subject to periodic review and users are cautioned to obtain the latest edition.
IGC Doc 44/00/E
Table of Contents
1 Introduction ........................................................................................................................................1
2 Scope and purpose ............................................................................................................................1
3 Definition ............................................................................................................................................1
4 General ..............................................................................................................................................1
4.1 Oxygen means life......................................................................................................................1
4.2 Inert gases give no warning........................................................................................................1
4.3 Inert gases act quickly................................................................................................................2
4.4 Ambiguity of inert gases .............................................................................................................2
4.5 Watchfulness with regard to inert gases ....................................................................................2
5 Typical situations................................................................................................................................2
5.1 Work in confined or potentially confined spaces .....................................................................2
5.2 The use of liquid nitrogen ...........................................................................................................2
5.3 Stay in areas where inert gases can flow out .............................................................................2
5.4 Erroneous use of nitrogen instead of air ....................................................................................2
6 Preventive measure ...........................................................................................................................3
6.1 Information, training....................................................................................................................3
6.2 Installation and operation ...........................................................................................................3
6.3 Ventilation and atmosphere monitoring......................................................................................3
6.3.1 Areas where people regularly work or enter.....................................................................3
6.3.2 Entry into enclosure or vessels..........................................................................................3
6.3.3 Entry into confined spaces ................................................................................................4
6.4 Testing of oxygen content ..........................................................................................................4
6.5 Work permit................................................................................................................................5
6.6 Lock-out procedure ....................................................................................................................5
6.7 Protection of personnel...............................................................................................................5
7 Rescue and first-aid ...........................................................................................................................5
7.1 Basic rules ..................................................................................................................................5
7.2 Equipment ..................................................................................................................................6
7.3 Procedure ...................................................................................................................................6
8 Conclusions........................................................................................................................................6
9 References.........................................................................................................................................6
Appendix A ......................................................................................................... Summary for operators
Appendix B .................................................................................. Accidents involving oxygen deficiency
Appendix C.....................................................................................................................Example of sign
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1 Introduction
EIGA continues to be very concerned thatevery year fatalities and serious accidents arereported by industrial gas companies andusers of inert gases where the direct causehas been the lack of oxygen leading toasphyxiation. EIGA identified that existinginformation on the hazards of inert gases wasnot sufficiently directed at the users who weremost at risk. This document sets out theessential information that is necessary toprevent asphyxiation accidents involving inertgases.
2 Scope and purpose
This document is intended to be used as atraining package suitable for supervisors, linemanagers and direct workers at anyinstallations where inert gases are produced,stored or used, or where oxygen depletioncould occur.
This document has 4 parts:
The actual document is intended for linemanagers and supervisors and gives thebackground of the subject, the typicaldescription of oxygen deficiency accidents andthe recommended rescue procedure in case ofaccident.
Appendix A is a resume of the actualdocument suitable to be produced as apamphlet to be handed over to workers.
Appendix B lists some actual accidents whichhave taken place in recent years and whichcan be used as examples underlining thehazards of inert gases.
Appendix C gives an example of a specialsign or poster highlighting the hazards of inertgases.
3 Definition
Inert gas: A gas which is not toxic, whichdoesn’t support human breathing and whichreacts scarcely or not at all with othersubstances. Inert gases are mainly nitrogenand the rare gases like helium, argon, neon,xenon, krypton.
4 General
Accidents due to oxygen depletedatmospheres are often very serious, and inmany cases fatal.
In spite of the wealth of information available,such as booklets, films and audio-visual aids,we still have reports of serious accidents dueto asphyxia caused by the improper use ofinert gases or by oxygen depletion.It is therefore absolutely essential to draw theattention of our personnel, as well as that ofour customers, to the hazards of inert gasesand oxygen depletion.Although carbon dioxide is not an inert gas,most of the information in this document isapplicable. The specific hazards of carbondioxide are more complex than those of inertgases and this document does not cover theseaspects. (More details about hazards of carbondioxide see in IGC Doc. 67/99 “CO2 cylindersat user’s premises”).
4.1 Oxygen means life
Oxygen is the only gas which supports life. Thenormal concentration in the air which webreathe is approximately 21 %.
If the oxygen concentration in air decreases or(what amounts to the same), if theconcentration of inert gases increases, asituation is rapidly reached where the hazardsof asphyxia become very great. Any depletionof oxygen below 21 % must be treated withconcern:
NOTE
• The situation is hazardous as soon as theoxygen concentration is less than 18 %.
• The risk of death due to asphyxia is almostcertain at an oxygen concentration below10 %.
• Immediate loss of consciousness occurswith less than 6 % of oxygen.
• Inhalation of only 2 breaths of nitrogen orother inert gas can cause sudden loss ofconsciousness and death.
4.2 Inert gases give no warning
It is to be strongly stressed that with such inertgases as nitrogen, argon, helium, etc.,asphyxia is insidious since there are nowarning signs. (Lack of oxygen may causevertigo, headache, speech difficulties but thevictim doesn’t recognise these symptoms asasphyxiation.)
• Inert gases are odourless, colourless andtasteless. They can therefore be a greatdeal more dangerous than toxic gasessuch as chlorine, ammonia, or hydrogen
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sulphide, which can be detected by theirodour at very low concentrations.
• For an unaware person, the asphyxiatingeffect of inert gases takes place withoutany preliminary physiological sign thatcould alert the victim. This action is veryrapid: only a few seconds for very lowoxygen contents. Stated clearly, “you donot notice that you are passing away!”
4.3 Inert gases act quickly
In the case of an accident, it is to be noted thatthe rapidity of emergency rescue is particularlycritical to save the victim: it is a matter of a fewminutes only if the victim is to be saved fromirreversible brain damage or even death.
Furthermore, and this is often poorlyunderstood, the emergency rescue procedureto save the victim must be carefully thought outin advance to avoid a second accident, wheremembers of the rescue team can becomevictims.
4.4 Ambiguity of inert gases
Finally, and especially with customers, onemust be aware of the ambiguity of theexpression “inert gas” (sometimes called“safety gas”, when it is used to prevent fire orexplosion), whereby an “inert gas” is oftenperceived, understood and wrongly taken to bea harmless gas!
4.5 Watchfulness with regard to inertgases
Considering the hazards mentioned above, it isessential to provide all those who handle oruse inert gases (both our own personnel aswell as that of our customers) with all theinformation and training necessary regardingsafety instructions. This includes means ofprevention and procedures to be respected toavoid accidents, as well as rescue proceduresto be implemented in the event of an accident.
5 Typical situations
5.1 Work in confined or potentiallyconfined spaces
Particularly dangerous are these situationswhen an inert gas has accumulated and hasnot been vented or purged, and the renewal ofair is poor or inadequate.
Examples for such spaces:
• Confined spaces: tanks, vessels,reservoirs, underground galleries, theinside of “cold boxes” of liquefactionequipment, cold storage rooms, spaces,where welding protective gas is used, etc.
• Potentially confined spaces: the internalrooms of a building, laboratory rooms,machine pits, culverts, basements,trenches for piping, or the room where adeep-freezing tunnel has been installed forfood freezing, or under a roof wherehelium (lighter than air) might haveaccumulated, etc.
5.2 The use of liquid nitrogen
It is to be noted, that the use of liquid nitrogenis accompanied by two hazards:
• Firstly it is a very cold fluid (-196°C), whichcan cause serious burns on contact withthe skin.
• Secondly it becomes, after vaporisation, abig volume of cold inert gas (1 litre liquidnitrogen yields 700 litres gaseous nitrogen)which has a tendency to accumulate in lowpoints.
In processes where liquid nitrogen is handledand vaporisation takes place, special caremust be taken to avoid exposure of personnelto oxygen deficiency.
5.3 Stay in areas where inert gases canflow out
Asphyxiation risk can arise in the vicinity of
• gas leaks,• vent exhausts,• outlet of safety valves and rupture disks,• openings of machines in which liquid
nitrogen is used for freezing,• in rooms, where dewars are filled and/or
stored.
5.4 Erroneous use of nitrogen instead ofair
In factories, there are often compressednitrogen distribution networks used for safetypurposes, e.g. inerting/purging or usingnitrogen as a pressure source to operatepneumatic tools (such as jackhammers) or asinstrument fluids.
Pneumatic tools can be operated either withcompressed nitrogen or compressed air, as isalso the case for instrument fluids.
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In the case of instrument air it’s worth notingthat, if the instrument air compressor fails,nitrogen gas is often used as a substitute. Onemust not forget that most pneumatic operatedinstruments vent continuously and that thevented nitrogen accumulated behind thecontrol panel presents a serious asphyxiationrisk.
Should a need arise for breathing air, andproper training and information have not beengiven, there is a risk that the breathingapparatus is connected into the nitrogensystem with fatal results.
6 Preventive measure
6.1 Information, training
The very first preventive measure is to informall persons who handle or who use inert gases:
• of the hazard represented by the depletionof oxygen in the atmosphere,
• of preventive measures to be adopted,• of procedures to be observed should an
accident occur.
This information and training should besystematically and periodically renewed inorder to maintain a state of watchfulness withregard to these hazards.
6.2 Installation and operation
Apparatus used for manufacture, distribution oruse of inert gas must be installed according tothe recommendations of the industrial gasindustry and must comply with all applicableregulations.
Newly assembled equipment for inert gasservice must be leak-checked by a suitableprocedure.
Each inert gas pipeline entering a buildingshould be provided with an isolation valveoutside the building.
Discontinued inert gas lines shall be physicallydisconnected from the supply system when notin use.
At the end of each work period, all valveswhich stop inert gas supply, shall be securelyclosed to avoid possible leakage between workperiods.
6.3 Ventilation and atmospheremonitoring
There are typically 3 situations where the typeand quantity of ventilation must be determinedin order to avoid asphyxiation accidents.
6.3.1 Areas where people regularly work orenter
Examples of this category would include:
• Rooms in which liquid nitrogen foodfreezers are operated.
• Rooms in which cryogenic deflashingequipment is operated.
• Control rooms (control/analyser panels).• Compressor houses (inert gases).• Rooms containing inert gas pipelines with
possible leaks.• Rooms in which dewars are filled and/or
stored.
Building size, ventilation capacity, systempressures, etc. must each be determined forspecific cases to which the following guidelinesapply:
• Ventilation must be continuous. This canbe achieved by interlocking the ventilationsystem with the process power supply.
• Ventilation system design should ensureadequate air flow around the normaloperating areas.
• Minimum ventilation capacity of 6 airchanges per hour.
• Other indicating devices may include:- warning lights- “streamers” in the fan outlet,- flow switches in the suction channels
(ideally monitoring should not rely onlyupon secondary controls like “poweron” to the fan motor).
• Exhaust lines containing inert gases to beclearly identified, and piped to a safe, wellventilated area.
• Consideration should be given to the useof atmosphere analyser, e. g. personaloxygen analyser or an analyser in the workarea.
6.3.2 Entry into enclosure or vessels
These would include enclosures or vesselswhich:
• are not routinely entered and• are known to have contained inert gas or• may contain inert gas
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Examples in this category would include:
• vessels designed to contain compressedor liquefied gases,
• filter vessels,• any vessel not known and verified to
contain atmospheric air.
In these cases the following guidelines applyprior to entry:
• The vessel or enclosure must beadequately purged with air (i. e. removethe inert gas and substitute with air).
• It is necessary to have at least 3 airchanges within the enclosure involved.
• Purging shall continue until analysisconfirms that the quality of the vesselatmosphere is safe for personnel entry. Ifthere is any doubt that effective purginghas taken place, the analysis should bemade in the interior of the vessel by takinga sample at several locations by probe, orif this is not possible, by a competentperson using a self contained breathingapparatus.
• The purge system must ensure turbulencefor adequate mixing of air and inert gas totake place (to avoid “pockets” of dense orlight inert gases remaining or to avoid“channelling” of gases due to inadequatepurging).
• Removal of argon or cold nitrogen fromlarge vessels and deep pits can be difficultdue to the relatively high density of the gascompared with air. In that case the gasshould be exhausted from the bottom ofthe space.
• Ventilation should never be carried out withpure oxygen, but exclusively with air.
• Another method of removing inert gases isto fill the vessel with water and allow air toenter when the water is drained off.
• A work permit must be issued and signedbefore entry is allowed.
• Sources of inert gas must be positivelyblinded or lines disconnected. Never relyonly on a closed valve.
• Oxygen content of the atmosphere in theenclosure/vessel should be monitoredcontinuously or repeated at regularintervals.
• Consideration should also be given to theuse of personal oxygen monitors.
6.3.3 Entry into confined spaces
A confined space is a space which has any ofthe following characteristics:
• limited opening for entry and exit,• unfavourable natural ventilation,• not designed for continuous worker
occupancy.In the majority of cases the presence of inertgases is not expected when entry into areasbelow ground level is required.The one essential safeguard, in all cases, is tosample the atmosphere in the trench, pit, etc.prior to any entry.The fact that a problem is not normallyanticipated is the greatest danger.
Notes:
The data for air change mentioned above isvalid where nitrogen is the inert gas involvedbecause its density is very near to that of airand oxygen.
If the gas to be purged has a density verydifferent from the density of air, such ashelium, argon or carbon dioxide, etc. theventilating air may not adequately mix and thepurge may be inadequate.
For inert gases of this type the volume of gasto be displaced (air changes) must be at least10 times that of the volume involved. Thepreferred method of removal of very densegases (e.g. argon or cold nitrogen vapour) is tosuck out the gas from the bottom of the space.
In the presence of toxic or flammable gases, itis mandatory to perform an analysis of thegases present in the confined space, beforeentry of personnel. For obvious reasons, themeasurement of only the oxygen content is notsufficient in this case. All other dangerous ortoxic gases must also be analysed.
In the specific case of flammable gases, anitrogen purge must be used first to preventany explosion risk and then subsequentlypurge with ventilating air.
6.4 Testing of oxygen content
Historically, the need to check that anatmosphere is respirable has been consideredto be of the greatest importance. In the past,simple means were employed, such as, forexample, the lighted candle or the canary bird.
At present, various types of oxygen analysersare used, which are often simple and reliably tooperate. The selection of the type of apparatusdepends on the nature of the work in the placeto be monitored (presence of dust,
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temperature and humidity, multiple detectors,portable equipment, etc.).
• Testing of the oxygen content isnecessary, although attention must bedrawn on the fact that an analyser alone isnot an absolute protection, since suchequipment can malfunction or beunexpectedly out of calibration, ordetectors can be improperly positioned.Testing of oxygen content should thereforeonly be considered as an aid to thedetection of a lack of oxygen.
• A simple check to confirm that an oxygenanalyser is operating properly is to checkthe oxygen content of the open air (21%).This check should be part of work permitrequirements.
• All oxygen analysers should be fitted withan alarm device to indicate possibledefects (e.g. low battery).
6.5 Work permit
• For certain types of work, safetyinstructions and a special work proceduremust be set up in the form of a workpermit, in particular for confined spacesentry.
• This procedure is also necessary duringwork carried out by subcontractors in airseparation plants, or where vessel entry isrequired.
• One of the important points that such adocument should deal with is detailedinformation that must be given to thepersonnel and contractor employeesbefore the start of work. This shouldinclude contractual conditions together withdocumented training to site workers beforestarting the job.
6.6 Lock-out procedure
A stringent implementation of a formal lock-outprocedure is necessary before entry to aconfined space.
6.7 Protection of personnel
Depending on the type of work to beperformed, and the layout of the premises, thedecision to provide additional protection forpersonnel may be taken on the initiative of theperson in charge. Such additional protectionmay involve:
• The use of warning signs against thepresence of an asphyxiation hazard (An
example is shown in appendix C). Thewarning sign shall be associated withprotective measures.
• The placing of a person on watch on theoutside in the case of work in a confinedspace.
• Having a self contained breathingapparatus on stand by.
• The wearing of a harness so that theworker can be easily and rapidly taken outof an enclosed space in the case of anemergency. Preferably, this harness is tobe connected to a hoist to facilitateremoving the victim. In fact, it is verydifficult for one person to lift up anotherperson in the absence of a hoist.
• The provision of an alarm system in caseof an emergency.
• The wearing of a self contained breathingapparatus (not cartridge masks, which areineffective in a case of lack of oxygen).
• The wearing of protective goggles andgloves when handling liquid nitrogen toavoid cold burns.
• The wearing of all other means ofprotection, such as safety shoes, helmet,etc., depending on the circumstances.
7 Rescue and first-aid
Training in rescue work is fundamental sincequickly improvised rescue without the respectof a formal procedure, often proves to beineffective, if not catastrophic. (The rescueworker lacking foresight becomes a second oreven a third victim).
It is recommended that where rescue is to beperformed, there is in place an annualprogramme of training and rescue drills.
7.1 Basic rules
If a person suddenly collapses and no longergives any sign of life when working in a vessel,a partially enclosed space, a trench, a pit, asmall sized room, etc., assume that the personmay lack oxygen due to the presence of aninert gas (which is, as we mentioned,odourless, colourless and tasteless),but
WARNING. Do not hurry to help him withoutthinking!
The risk is that you will become the secondvictim, which obviously must be avoided at allcosts.
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You can only be the person who will save thevictim if you proceed in an orderly manner andif you have the necessary equipment andrestrain yourself against your natural impulses.
Get proper assistance and support.
7.2 Equipment
For a successful rescue action you need inwhole or in part:
• A self-contained breathing apparatus forthe rescue worker. WARNING: Cartridgemasks for toxic gases are not suitable.
• A resuscitation kit supplied with oxygen forthe victim. In general, such a kit includes asmall oxygen cylinder, a pressureregulator, an inflatable bag, and a mask tocover both the nose and mouth of thevictim (not compulsory).
• A safety belt or harness connected to aline on a hoist to attach to the victim.
• A portable audible alarm device, e. g.personal horn, whistle, klaxon etc. to alertnearby people that assistance is required.
• Possibly a source of air or oxygen, suchas, for example:- a compressed air hose connected to
the plant compressed air network,- an oxygen cylinder from an
oxyacetylene work station, which mightbe located in the vicinity of the victim(only to be used in this special case ofemergency rescue).
- A ventilation device.
It is to be noted that all this equipment isnecessary for emergency rescue in placeswhere the rescue work might prove difficultdue to the narrow space. Where thisequipment is not available, a rescue should notbe undertaken.
7.3 Procedure
The procedure to be followed (as describedwith illustrations in pages 8 to 13) includes 3distinct situations:
1st situation It is possible to take the victimout into the open air in a few minutes (lessthan 3 minutes) without any additionalassistance and without penetrating into thedangerous atmosphere.Be aware that it is almost impossible for oneperson to lift another person out of a vessel.So in this situation a lifting device is necessary.
2nd situation It is possible to take the victimout into the open air in a few minutes (lessthan 3 minutes) without any additionalassistance, although it is necessary topenetrate into the dangerous atmosphere. Inthis situation the rescuer must use selfcontained breathing apparatus when enteringthe confined space.
3rd situation It is impossible to take thevictim out into the open air in a few minutesand without additional help.
In all situations, if there is in the immediatevicinity of the victim a source of air or oxygen(see above) and if it is possible for you to veryrapidly use it, then inject the compressed air oroxygen into the enclosed space where thevictim is to be found.WARNING: Inject oxygen only, if there is noignition source.
8 Conclusions
At this time, it is necessary to recall theessential two points relative to accidents due toinert gases:• Accidents due to inert gases always
happen unexpectedly and the reactions ofpersonnel may be incorrect. Because ofthis awareness of personnel with regard tothe hazards of inert gases must bepermanently maintained.
• Furthermore, when such an accident doesoccur, it is always serious, if not fatal andhence, the absolute necessity to carry outregularly and periodically training andawareness sessions for personnel, as wellas rescue work drills.
Use this document to train your employees andyour customers.
9 References
[1] Accident prevention in oxygen-rich andoxygen-deficient atmosperesCGA Doc. P14, 1992
[2] Oxygen deficiency awareness trainingpackage. Overhead slides series.EIGA, 1997
[3] Oxygen deficiency hazards. Video tape.EIGA, 1997
IGC Doc 44/00/E
RESCUE PROCEDURES
1st SituationIt is possible to TAKE THE VICTIM OUT intothe open air IN A FEW MINUTES, WITHOUTASSISTANCE, and WITHOUT PENE-TRATING into the dangerous atmosphere.
For example:• the victim is inside a CONTAINER;• the victim is wearing the HARNESS;• the LINE and HOIST are in place.
Then: Keep your head out of the confinedspace and....
WITHOUT LOSING ANY TIME
TAKE THE VICTIM OUT into the open air.Place him on his back.
CALL FOR HELP.It is necessary for someone to ALERT asquickly as possible SPECIALIZED RESCUEPERSONNEL (Medical Emergency VehicleService, Doctor, Nurse)
TELEPHONE No.
ORGANIZATION
IWNbt
ItyT
IIBAV
IvO
f you have resuscitation equipment.HETHER THE VICTIM IS BREATHING OROT, open the valve of the cylinder (flowrateetween 3 and 5 litres/min.), put the mask over
he face of the victim.
f the victim is no longer breathing, squeezehe inflatable bag according to the rhythm ofour own respiration, and CONTINUE UNTILHE VICTIM STARTS BREATHING AGAIN
f you do not have resuscitation equipment andF THE VICTIM IS NO LONGERREATHING; carry out MOUTH TO MOUTHRTIFICIAL RESPIRATION, UNTIL THEICTIM STARTS BREATHING AGAIN.
7
f resuscitation equipment has been used, theictim should keep it on UNTIL THE ARRIVALF SPECIALIZED EMERGENCY RESCUE
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PERSONNEL, even if the victim startsbreathing again.
Inform very clearly the Medical EmergencyVehicle Service doctor or nurse that it is amatter of ANOXIA (for example, pin on theclothing of the victim a LARGE LABEL withthe wording ANOXIA* LOSS OFCONSCIOUSNESS AT ........O’CLOCK).
*Anoxia is the medical term for lack of oxygen.
IGC Doc 44/00/E
RESCUE PROCEDURES
2nd Situation
It is possible to TAKE THE VICTIM OUT intothe open air.
IN A FEW MINUTES, and WITHOUTASSISTANCE;with the need to penetrate into the dangerousatmosphereIf possible CALL for HELP before penetratingwith the breathing equipment.
Then
PUT ON THE RESPIRATOR(Check that it is operating properly) and thengo to the victim.
TAKE HIM OUT into the open air. Put him onhis back and remove your mask.
CALL FOR HELP: It is necessary to ALERTas quickly as possible SPECIALIZED RESCUEPERSONNEL (Medical Emergency VehicleService – MEVS, doctor, nurse)
TELEPHONE No.
ORGANIZATION
.
If you have resuscitation equipment
WNbt
IioV
IaIBcRB
HETHER THE VICTIM IS BREATHING OROT, open the valve of the cylinder (flowrateetween 3 and 5 litres/mn); put the mask over
he victim’s face.
f the victim is not breathing, squeeze thenflatable bag according to the rhythm of yourwn respiration and CONTINUE UNTIL THEICTIM STARTS BREATHING AGAIN.
f you do not have resuscitation equipmentndF THE VICTIM IS NO LONGERREATHING;arry out MOUTH TO MOUTH ARTIFICIALESPIRATION UNTIL THE VICTIM STARTSREATHING AGAIN.
9
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If resuscitation equipment has been used, thevictim is to keep it on UNTIL THE ARRIVALOF SPECIALIZED MEDICAL RESCUEPERSONNEL, even if the victim startsbreathing again.
Inform very clearly the Medical EmergencyVehicle Service doctor or nurse that it isprobably a case of ANOXIA (for example, pinon the clothing of the victim a LARGE LABELwith the wording ANOXIA* LOSS OFCONSCIOUSNESS AT ..........O’CLOCK).
*Anoxia is the medical term for lack of oxygen
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RESCUE PROCEDURES
3rd Situation
It is IMPOSSIBLE TO TAKE THE VICTIMOUT very quickly and without assistance.
ThenWITHOUT LOSING ANY TIME
CALL FOR HELP, as you will surelyNEED ASSISTANCE
PUT ON THE RESPIRATOR (check that it isoperating properly).
If necessary attach yourself to a line.
Take the RESUSCITATION EQUIPMENT as itis indispensable.
Without losing any time, go to the victim.
Open the valve of the resuscitation equipment(flowrate between 3 and 5 litres/min.) ; put themask over the victim’s face (as soon as youcan, attach VERY FIRMLY the head strap).
IF THE VICTIM IS NO LONGERBREATHING, squeeze the inflatable bagaccording to the rhythm of your own respirationand CONTINUE UNTIL THE VICTIM STARTSBREATHING ONCE AGAIN.
HOWEVER, IF YOU HEAR THE CYLINDEROF YOUR MASK WHISTLE, YOU MUSTRETURN TO THE OPEN AIR WITHOUTDELAY
RESCUE WORKERS who have come toprovide ASSISTANCE and remain IN THEOPEN AIR ARE TO ALERT immediatelySPECIALIZED RESCUE SERVICES: MedicalEmergency Vehicle Service doctor or nurse.
TELEPHONE No.
ORGANIZATION
They will do what is necessary to BRING thevictim BACK OUT into the open air.
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For example:
A. If this is possible, make the atmosphererespirable by sending in LARGEQUANTITIES OF AIR with a large fan.
B. Or organize REMOVAL with a LINE andHOIST.
C. Or organize the TRANSPORTATION inthe ARMS of rescue workers EQUIPPEDwith RESPIRATORS
D. Or drill an OPENING in a GOOD PLACEin a container.
If resuscitation equipment has been used, thevictim is to keep it on UNTIL THE ARRIVALOF SPECIALIZED RESCUE PERSONNEL,even if the victim has started breathing again.
Inform very clearly the MEVS, doctor or nursethat it is probably a case of ANOXIA.
(For example, pin onto the clothing of thevictim a LARGE LABEL with the wordingANOXIA* LOSS OF CONSCIOUSNESS AT......O’CLOCK).
APPENDIX A
SUMMARY FOR OPERATORS
1 Why do we need oxygen?
OXYGEN IS LIFE
WITHOUT ENOUGH OXYGEN YOUCANNOT LIVE
When the natural composition of air ischanged, the human organism can be affectedor even severely impaired.
If gases other than oxygen are added ormixed with breathing air, the oxygenconcentration is reduced and oxygendeficiency occurs.
If oxygen deficiency occurs by the presence ofinert gases (e. g. nitrogen, helium, argon,etc.) a drop in physical/mental efficiencyoccurs without the person’s knowledge; atabout 10 % oxygen concentration in air(instead of the normal 21 % concentration)fainting occurs without any prior warning.
Below this 10 % concentration death due toasphyxia occurs within a few minutes, unlessresuscitation is carried out immediately.
2 Causes of oxygen deficiency
a) When liquefied gases (such as liquidnitrogen, liquid argon, liquid helium)evaporate, one litre of liquid producesapproximately 600 to 850 litres of gas.This enormous gas volume can veryquickly lead to oxygen deficiency unlessthere is adequate ventilation.
b) In the event of gases other than oxygenleaking out of pipework, cylinders, vessels,etc., oxygen deficiency must always beexpected. Checks should be madeperiodically for possible leaks.
Spaces with inadequate ventilation (e.g.vessels) must not be entered unless airanalysis has been made and a workpermit has been issued.
c) If work has to be carried out in the vicinityof ventilation openings or vent pipes,personnel must be prepared to encountergases with upper case low oxygenconcentration or without oxygen at allleaking out of these openings.
d) Oxygen deficiency will always arisewhen plant and vessels are purged withnitrogen or any other inert gases.
Detection of oxygen deficiency
HUMAN SENSES CANNOT DETECTOXYGEN DEFICIENCY
Measuring instruments giving an audible orvisual alarm in case of oxygen deficiency onlyindicate the oxygen content.
These instruments should always be tested inthe open air before use.
APPENDIX A
If the presence of toxic or flammable gases ispossible, specific instruments should be used.
3 Breathing equipment
Breathing equipment must be used insituations where oxygen deficiency has to beexpected and which cannot be remedied byadequate ventilation.
Cartridge gas masks necessary for use in thepresence of toxic gases (such as ammonia,chlorine, etc.) are useless for this purpose.
Recommended type of breathing equipmentare:
• Self contained breathing apparatus usingcompressed air cylinders;
• Full face masks with respirator connectedthrough a hose to a fresh air supply.
NOTE:! It should be born in mind that when
wearing these apparatus, particularly withair filled cylinders, it may sometimes bedifficult to enter manholes.
! Periodic inspection of the correctfunctioning of the equipment shall becarried out in accordance with localregulations.
! Practice in handling of the equipment shallbe carried out regularly.
4 Confined spaces, vessels, etc.
Any vessel or confined space where oxygendeficiency is expected and which is connectedto a gas source shall be disconnected fromsuch a source:
by the removal of a section of pipe;orby inserting a blanking plate before andduring the entry period.
NOTE. Reliance on the closure of valves alonemight be fatal.
A space or vessel should be thoroughlyventilated, and the oxygen content shall bemeasured periodically before and duringentry period.
If the atmosphere in such a vessel or space isnot breathable, breathing equipment shall beused by a qualified person.
Permission to enter such a space shall begiven only after the issue of an entry permitsigned by a responsible person.
As long as a person is in a vessel or confinedspace, a watcher shall be present andstationed immediately outside of the confinedentrance.
He shall have a self contained breathingapparatus readily available.
A harness and rope shall be worn by theperson inside the confined space to facilitaterescue. The duty of the watcher should beclearly defined. A hoist may be necessary to liftan incapacitated person.
5 Emergency Measures
In the event of a person having fainted due tooxygen deficiency, he can only be rescued ifthe rescue personnel are equipped withbreathing apparatus enabling them to enterwithout risk the oxygen deficient space.
Remove the patient to the open air and withoutdelay administer oxygen from an automaticresuscitator if available or supply artificialrespiration.
Continue until patient revives or advised tostop by a medical doctor.
APPENDIX B
ACCIDENTS INVOLVING OXYGENDEFICIENCY
1. An argon tanker had its top accessmanhole cover removed. An apprenticeaccidentally dropped a securing nut insidethe tank. He entered the tank to recover itand died from lack of oxygen.
2. A new pipeline in a trench was being prooftested with nitrogen. A chargehand enteredthe trench to investigate the cause of anaudible leak. He was overcome by nitrogenand died.
3. A workman was overcome by lack ofoxygen after entering a large storage tankwhich had been inerted with nitrogen. Twoof his workmates who went to his aid,without wearing breathing equipment, werealso overcome and all three died.
4. A man was overcome on entering a steeltank which had been shut up for severalyears. The atmosphere inside the tank wasno longer capable of supporting life due toremoval of oxygen from the air by therusting of steel.
5. A worker from a contractor company hadto carry out welds inside a vessel. Thevessel had been under a nitrogen blanket,but was ventilated with air before workstarted. In order to be on the safe side, thewelder was asked to wear a fresh airbreathing mask. Unfortunately a fellowworker connected the hose to a nitrogenline and the welder died from asphyxiation.
This accident happened because thenitrogen outlet point was not labelled andhad a normal air hose connection.
6. Welding work with an argon mixture wasperformed inside a road tanker. Duringlunchtime the welding torch was left insidethe tank, and as the valve was not properlyclosed, argon escaped. When the welderre-entered the tank, he lostconsciousness, but was rescued in time.
Equipment that is connected to a gassource, except air, must never be leftinside confined spaces during lunchbreaks, etc. Merely closing the valves isnot a guarantee against an escape of gas.If any work with inert gas is carried out invessels, etc. take care with adequateventilation or the use of proper breathingequipment.
7. A driver of a small-scale liquid nitrogendelivery service vehicle was making adelivery. He connected his transfer hose tothe customer installed tank which wassituated in a semi-basement. After he hadstarted to fill, one of the customer’semployees told him that a cloud of vapourwas forming around the tank. The driverstopped the filling operation and returnedto the area of the tank to investigate. Onreaching the bottom of the stairs, hecollapsed, but fortunately he was seen byone of the customer’s staff who managedto put on breathing apparatus, go in anddrag the man to safety. The driver fullyrecovered.
Unknown to the driver, the bursting disc ofthe storage tank had failed prior to the startof his fill and as soon as he started filling,nitrogen escaped in the vicinity of thestorage tank. He was overcome by theoxygen deficient atmosphere when hewent down to investigate without wearinghis portable oxygen monitor which wouldhave warned him of the oxygen deficiency
The installation has been condemned andis no longer being used. Not only was thetank situated in a semi-basement, but therelief device was also not piped to a safearea.
8. In a gas mixing unit the glass of a nitrogenflow meter ruptured while nobody wasinside the room. When passing that room,a worker heard the noise of the escapinggas and he entered the room to see whathad happened. As he immediately feltunwell, he tried to leave the room. He felloutside the door and called for help just intime.
In order to prevent a repetition, all-metalflow meters will be used in future and ashut-off device that trips at a rapidpressure drop will be installed in the fillline.
9. During a routine overhaul of an ASU plant,a maintenance technician had the task ofchanging the filter element on a liquidoxygen filter. The plant was shut down anda work permit was issued each day foreach element of work. In spite of theseprecautions, the technician collapsed whenhe inadvertently worked on the filter after ithad been purged with nitrogen. The fittercollapsed apparently asphyxiated bynitrogen. All efforts to revive him failed.
APPENDIX B
10. A paint sprayer’s breathing air hood wasconnected to a nitrogen supply instead ofair. Saved by mouth to mouthresuscitation.
11. Reaching inside a refractory lined verticalvessel under nitrogen purge to remove agrating for maintenance, a man collapsedand was saved by mouth to mouthresuscitation.
12. Two contractors entered an enclosureunder nitrogen purge to start work withoutpermission. Both saved by cardiacmassage and mouth to mouthresuscitation.
13. Two fatalities at a hospital during freezingof a pipe with liquid nitrogen formaintenance.
14. Two men became dizzy and nearlycollapsed while descending into a sewageejector pit operated by nitrogen instead ofcompressed air.
15. Two fatalities from asphyxiation when twotechnicians went to investigate, why anatural gas pipeline they were pressure-testing would not hold nitrogen pressure.
16. A food freezing machine did not properlyvent off the waste nitrogen because aplastic bag was wrapped around the fanblades. Oxygen deficiency alarm from theanalyser warned personnel.
17. At a cryogenic application, the equipmentpressure relief valve located on theequipment inside the building opened
because the pressure in the storage tankoutside increased above the setting of theequipment pressure relief valve. Personnelabout to enter the room the next morningwere warned by the frosted appearanceand did not enter.
18. At a customer location where liquidnitrogen dewars were filled from a storagetank, the customer built a shed to protectpersonnel against wind and rain. In theclosed shed one person lostconsciousness.
19. A customer was supplied with 2 lowtemperature grinding machines which werelocated in the same area in the factory.The customer installed a joint nitrogenextraction system between the twomachines.
One machine was switched off for cleaningwhile the other machine was left running.One of the operators who had entered theunit for cleaning fell unconscious and wasasphyxiated before help arrived.
The linked extraction system had allowedexhausted nitrogen from the operatingmachine to flow into the unit to be cleaned.
These examples from the recent past, highlightthat it is absolutely essential to regularly drawthe attention of our personnel, as well asthose of our customers, to the hazards ofinert gases and oxygen deficiency.
APPENDIX C
