cosh_carbon_dioxide.pdf

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Issued October 2000Page 2 of 7

Specification and typical analysis

Bulk liquid carbon dioxide supplied by Distillers MG Limited will meet the followingspecifications:BS 4105: 1990 Type 2 EEC Council Directive 65/66 EEC E290Miscellaneous Additives in Food Regulation 1980

Specification Typical analysisResidual gases 0.025% v/v 0.005%Water 50 mg/kg 9 mg/KgOil 2 mg/Kg 0.2 mg/KgSulphur compounds 0.5 mg/Kg < 0.1 mg/KgOxides of nitrogen 1 mg/Kg < 0.1 mg/KgCopper * < .01 mg/KgZinc 25 ppm * < 0.1 mg/KgCarbon monoxide passes the E290 test < 1.0 mg/KgTotal hydrocarbons 1.5 mg/KgHalogens < 0.1 mg/KgAmmonia < 1.0 mg/KgArsenic < 0.001 mg/KgCadmium < 0.1 mg/KgMercury < 0.01 mg/KgLead < 0.1 mg/KgSoda water taste satisfactory satisfactoryOdour of solid CO2 satisfactory satisfactory

* The total concentration of copper and zinc together shall not exceed 50 ppm.

Physical properties (pure)

Molecular weight 44.01

Vapour pressure (15C) 50.85 bar

Density of gas (15C, 1 bar) 1.8474 g/l

Specific gravity, gas (air = 1) 1.528Critical temperature 31.1CCritical pressure 73.825 barTriple point (5.185 bar) -56.6C

Solubility of gas in water (15C, 1 bar) 1.9786 g/l

ColourlessOdourless

Note: All pressures are absolute

WARNING: EXTREMELY COLD, ASPHYXIANT VAPOUR

Hazardous properties

Toxicity: Occupational exposure standard (OES)5,000 vpm

Short term exposure limit: 15,000 vpm (1.5%) calculated as a 10 minutetime weighted average.

Asphyxiant vapour: Vapour heavier than air.


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Liquefied gas in a pressure vessel under avapour pressure:

Approx. 20.7 bar g.

Note:Carbon dioxide cannot exist as a liquid at atmospheric pressure.

Large volume increase on phase change one volume of liquid will instantly produce 250volumes of gas plus a further 250 volumes once the solid has sublimed to gas under ambientconditions.

Slightly corrosive in the presence of moisture.

Solid carbon dioxide or cold vapour may cause cold burns or frost bite.

Safety Precautions

Responsibility: All users of bulk liquid dioxide shouldpossess a copy of the Health & SafetyExecutive Guidance Note CS9 entitled BulkStorage and Use of Liquid Carbon DioxideHazards and Procedures which states thatthe person in control of a carbon dioxideinstallation is responsible for its safetywhether the plant is owned, hired, leased orloaned. The user should therefore familiarisehimself with the recommendations made inCS9 and ensure that the carbon dioxide plantis properly maintained and operated in acorrect and safe manner. Distillers MGLimited may refuse to make deliveries intoany storage installation which has beenmodified or inadequately maintained andwhich is considered to be unsafe forcontinuing operation.

Fire and explosion hazards: Carbon dioxide is not flammable and doesnot constitute a fire hazard. However, bulkliquid carbon dioxide is stored under pressurein liquid storage vessels and it isrecommended that precautions are taken tolessen the risk of fire in the vicinity of thestorage vessel.eg. Combustible materials should not bestored near the vessel.

Should a fire occur then, if the refrigerationplant associated with the vessel is unable tooffset any heat ingress, the pressure within

the storage vessel will rise and ultimately thepressure relief valves will operate.

Material compatibility: Normal materials of construction are suitablefor dry gas at ambient temperature. Below


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30C only use low temperature carbon steel,austenitic stainless steels, aluminium andcopper and their alloys. If carbon dioxide isdissolved in water particularly at elevatedpressures, and in the presence of oxygen,use materials resistant to carbonic acid, eg.

18-8 stainless steel or Monel

Leak detection: Large leaks can usually be heard or can bedetected by noting the build up of frost at thedischarge point. For the detection of smallerleaks, apply soap solution to suspect sites ongas lines and equipment. Bubbling willindicate leaks.

Toxicity and symptoms: Carbon dioxide, which is normally present inatmospheric air at the level of approximately350 vpm (0.035%), regulates the breathingfunction and an increase in concentration willcause increased breathing rate. The

occupational exposure standard (OES) is5,000 vpm (0.5%), but changes in thebreathing rate may not be noticed until thereis a concentration of 20,000 vpm (2%) whenthe rate will increase to about 50% above thenormal level. Prolonged exposure at this levelfor several hours may cause a headache anda feeling of exhaustion.

At high concentrations carbon dioxide maycause asphyxiation and can paralyse therespiratory centre. Breathing an atmosphererich in carbon dioxide can cause immediateloss of consciousness and rapid death.Symptoms of asphyxiation may include rapidand gasping respiration, rapid fatigue,nausea, vomiting, cyanosis and may lead toloss of consciousness or death from anoxia.

Cold burns and frost bite: When bulk liquid carbon dioxide underpressure is released to the atmosphere thedischarge will consist of gaseous and solid

carbon dioxide at 78.5C. Exposure to thecold gas or solid carbon dioxide can causecold burns or frost bite. Local pain usuallygives warning of freezing but sometimes nopain is experienced. Shock may occur if theburns are at all extensive. Thawing frozentissues can cause intense pain.

Precautions

Protective clothing: Protective clothing is only intended to protectthe wearer handling cold equipment or fromaccidental contact with cold gas or solidcarbon dioxide. Non-absorbent insulatedgloves, goggles or a face mask should beworn to protect otherwise unprotected parts


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of the skin.

Atmosphere: It is essential that operations involving theuse of carbon dioxide, particularly when largequantities are used, are conducted in wellventilated areas to prevent the formation of

oxygen deficient atmospheres.Ideally, carbon dioxide should be vented intothe open air well away from areas frequentedby personnel. Carbon dioxide should NEVERbe released or vented into enclosed areas,pits, cellars or buildings where the ventilationis inadequate.

Carbon dioxide gas at ambient temperaturesis denser than air and can accumulate in lowlying areas such as pits and trenches.

Before entering areas, vessels or otherequipment, for maintenance or otherpurposes, in which the atmosphere is, or maybecome, deficient in oxygen, action shouldbe taken to make the equipment safe.Preparatory work will include equipmentisolation from hazardous processes, purgingand contained ventilation with air asappropriate.

Due to asphyxiation hazards any suspectatmosphere should be monitored for carbondioxide and lack of oxygen. There are anumber of both carbon dioxide and oxygenmeasuring devices available on the market todetect the level of carbon dioxide and ifnecessary oxygen in the atmosphere. Thesedevices will help warn the operator ifdangerous levels are present.

If it is necessary for a person to enter anoxygen deficient atmosphere formaintenance or other purposes it is essentialthat he wear and be trained in the use of selfcontained breathing APPARATUS.

Persons entering an oxygen deficient areaare recommended to wear a safety belt witha manned safety line attached. Standbypersonnel should have ready access to selfcontained breathing apparatus.

Over pressurisation: Care must be taken to ensure that all pipesor other closed systems in which bulk liquidcarbon dioxide can be trapped are protectedby a suitable relief valve. Otherwise,extremely high pressure, well in excess of thesafe working pressure of the system will begenerated as the system warms up


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creating a dangerous rupture hazard.

Emergency action

Inhalation (asphyxiation conditions): Minimising personal risk, immediately remove

the victim to an uncontaminated area. Ensurethere is no obstruction to the airways. Ifbreathing is weak or stopped, apply artificialrespiration with simultaneous administrationof oxygen, preferably using oxygenresuscitator. Summon am ambulance. Keepwarm and rested.

Cold burns and frost bite: In severe cases summon medical assistanceimmediately, Apply first aid as follows:Loosen or remove any clothing that mayrestrict circulation. Flush affected areas withcopious amounts of lukewarm (tepid) wateror place affected part in a container oflukewarm water. Move person to a warm (nothot) place. Do not apply direct heat to theaffected areas. Protect the affected areaswith dry, sterile, bulky dressings looselyapplied so as not to restrict circulation. In allcases seek medical attention as soon aspossible. Do not give affected personscigarettes or alcohol.

Hypothermia: Move person to a warm place and wrap inblankets. Do not apply direct heat. Do notgive cigarettes or alcohol. Seek medicalattention.

Carbon dioxide leak: In the event of a serious leak which couldgive rise to high levels of carbon dioxide:

Evacuate the area Post warning notices and seal off the

area

If it is necessary to enter the area, useappropriate breathing equipment such asself contained breathing apparatus, orother type of independent air supply.Absorptive respirators MUST NOT beused.

Fire fighting: Carbon dioxide is not flammable and nospecial fire fighting precautions or equipmentare needed. If an outbreak of fire occurs inthe vicinity of carbon dioxide storageequipment, the local Fire Brigade should besummoned at once. Effort should be made tokeep the heat of the fire away from thecarbon dioxide storage vessel.


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References H&SE Guidance Notes CS9: 1985 BulkStorage and Use of Liquid Carbon Dioxide:Hazards and Procedures.

H&SE Code of Practice

the Operational Provisions of the DangerousSubstances (Conveyance by Road in RoadTankers and Tank Containers) Regulations1981

H&SE Guidance Note EH40Occupational Exposure Limits

H&SE Code of PracticePressure Systems and Transportable GasContainers Regulations 1989

British Compressed Gas Association CP9(1982)The Safe Filling, Handling, Storage andDistribution of Gases in TransportableContainers.

Distillers MG LimitedSafety Data Book Bulk Carbon Dioxide

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