GAS PROPERTIES ALWAYS REFER TO SAFETY DATA SHEETS

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4 GAS PROPERTIES ALWAYS REFER TO SAFETY DATA SHEETS FLAMMABLE ACETYLENE C 2 H 2 PROPANE C 3 H 8 BUTANE C 4 H 10 HYDROGEN OXIDISING OXYGEN O 2 NITROUS OXIDE FLUORINE CHLORINE INERT NITROGEN N 2 ARGON Ar CARBON DIOXIDE HELIUM CORROSIVE CHLORINE AMMONIA TOXIC CARBON MONOXIDE SULPHUR DIOXIDE AMMONIA PYROPHORIC SILANE SPECIFIC 15 C IN RELATION TO AIR Helium 0.1 Hydrogen 0.06 Nitrogen 0.9 Acetylene 0.9 Oxygen 1.1 Argon 1.4 Carbon Dioxide 1.5 Propane 1.5

5 CRYOGENIC GASES GAS PROPERTIES This table is for guidance only. Refer to manufacturer s data sheets for full details. Gas Boiling Point Liquid - Gas Ratio Rises / Falls Gas C Specific Gravity Where Air = 1 Nitrogen -196 C 683 Rises 0.96 Argon -186 C 824 Falls 1.38 Hazards Inert. Asphyxiant. Inert. Asphyxiant. Oxygen -183 C 843 Falls 1.12 Helium -269 C 739 Rises 0.13 Liquid Carbon Dioxide Solid Carbon Dioxide Gas above -78 C Solid below -78 C Sublimates no liquid phase 10kg of Dry Ice sublimates to 5.4 cubic metres of gas Falls 1.5 Falls 1.5 Oxidising. Supports combustion. Reacts violently with hydrocarbons. Inert. Asphyxiant. Asphyxiant. Slight pungent odour at high concentrations. Notifiable under COSHH STEL: 1.5% LTEL: 0.5% Exposure may lead to rapid breathing & increased heart rate. STEL: Short Term Exposure Level LTEL: Long Term Exposure Level All these products may cause cold burns on contact & lung damage if the cold vapour given off during evaporation is inhaled.

6 CRYOGENIC GASES LIQUID TO GAS RATIOS Compression At Atmospheric pressure & room temperature a gas occupying a volume of 10 M 3 (10,000 Ltr) may be compressed at 200 bar to occupy a.05 M 3 (50 Ltr) cylinder of gas. The Advantage of Liquification The equivalent of 1,900 cylinders of pressurised Oxygen is contained in one cryogenic bulk tank making liquefied gas easier to transport & store. Evaporation Gaseous Oxygen will occupy an area 843 times larger than the initial volume of Liquid Oxygen. If 1 Litre of Liquid Oxygen (-183 C) is heated to a room temperature of 15 C at atmospheric pressure, the resulting gas will occupy a volume 843 times as big. Therefore 1,000 Litres (1M 3 ) of Liquid Oxygen (-183 C) heated to a room temperature of 15 C at atmospheric pressure the resulting gas will occupy a volume of 843,000 litres (843 M3). Evaporated Gas 843,000 ltrs 843cm3 Storage Tank 1,000 ltrs 1 cm3

7 CRYOGENIC GASES OXYGEN ENRICHMENT & DEFICIENCY Oxygen Enrichment & Nitrogen Transfer Hoses Nitrogen turns from gas to liquid at approximately -196 C. Oxygen turns from gas to liquid at approximately -183 C. The consequences are that Oxygen enrichment will take place around a hose containing Liquid Nitrogen as the gaseous Oxygen in the atmosphere begins to condense into liquid on contact with the cold surface of the Nitrogen hose. Resulting Hazards Oxygen enrichment around the hose area. The Liquid Oxygen may drip from the hose giving the impression there is a leak. The formed cryogenic liquid may then drip from the hose onto other surfaces causing embrittlement. Precautions NO SMOKING or naked flames around cryogenic transfer operations as there may be an increased fire risk. Oxygen Deficiency The air we breathe normally contains 20.9% Oxygen by volume. Increasing asphyxiant gases will reduce the concentration of Oxygen in the air. People vary in their reaction to Oxygen deficiency. Symptoms are: 21 g 14% Increasing pulse rate, tiredness 14 g 11% Physical movement & intellectual performance becomes difficult 11 g 8% Possibility of headaches, dizziness & fainting after short period of time 8 g 6% Fainting within a few minutes, resuscitation possible if carried out immediately 6 g 0% Fainting almost immediate, death or severe brain damage

8 CRYOGENIC GASES OXYGEN ENRICHMENT & DEFICIENCY Carbon Dioxide Enrichment 1% Possible slight increase in breathing rate. 2% Breathing becomes deeper - 50% above normal. After several hours may cause headaches & feeling of exhaustion. 3% Breathing becomes laboured - 100% above normal. 4 g 5% Effects as the above after 30 minutes signs of intoxication & slight choking feeling. 5 g 10% Characteristic pungent smell noticeable. Breathing heavily laboured leading to: Physical exhaustion Headaches Visual disturbances Ringing in the ears Loss of consciousness within minutes 12% Characteristic taste. 10 g 100% Loss of consciousness more rapid with risk of death from respiratory arrest. Increased concentration - greater hazard to life. Atmospheres containing: less than 20% Oxygen or more than 0.5% Carbon Dioxide should not be entered. REMEMBER The main 5 cryogenic gases are colourless, odourless & tasteless. Human reactions to Oxygen deficiency & Carbon Dioxide enrichment occur in a short space of time without the person s knowledge & without prior warning under some circumstances it can prove fatal. Do not attempt to enter gas filled areas without specialist breathing apparatus & training.

9 CRYOGENIC GASES OXYGEN MONITORS Human physiology may not detect Oxygen deficiency or enrichment Local atmospheres (confined spaces or small workspaces) can easily become highly Oxygen deficient or enriched as a result of the very high liquid to gas (LTG) ratios of Cryogenic gases. Oxygen monitors (either personal or for working area) must be available where cryogenic gases are being used. Oxygen monitors are normally set to activate at 1.5% deviation by the manufacturer. A typical response time for a 1% change in atmospheric oxygen to set off the alarm is seconds. Urgent investigation should be made if the alarm sounds at 19.5%. Immediate evacuation of the area must take place at 18% oxygen level. TYPICAL AREA MONITOR TYPICAL PERSONAL MONITOR

10 CRYOGENIC GASES HAZARDS OF COLD Frostbite Operators should be aware that continued exposure to cold may lead to frostbite, extreme cold destroys body tissue. The amount & duration of exposure are important factors in determining the amount of damage done. Destruction of body tissue is not always immediate or obvious. Remember cold surfaces present operator contact hazards. Skin may freeze instantly to cold surfaces, attempts to remove the skin from such surfaces could cause serious damage. Effects on Lungs Short exposure to breathing cold air will result in some discomfort, can provoke asthma attacks. Inhalation of cold mists, gases or vapours can be serious & lung damage may result. Hypothermia Possible in environments below 10 C Symptoms: Slow mental and physical response Unreasonable behaviour and irritability Speech or vision difficulties Cramps and shivers Treatment for Cold Burns Immerse or flush the affected skin with tepid water. Do not use direct heat sources such as hot water or room heaters. Remove casualty to a warm place & reassure. Seek medical attention immediately & if required arrange for casualty to be transported to hospital. Loosen any restrictive clothing. Continue flushing the affected skin with tepid water. Protect affected parts with bulky, dry, sterile dressings applied lightly so as not to cause restriction of blood circulation; an alternative is to use lightly applied kitchen clingfilm. Keep casualty warm & rested. Advise ambulance crew or hospital of first aid already administered. Do not administer alcohol or allow smoking as these reduce blood supply to affected parts.

11 CRYOGENIC GASES PPE Hazards of Cryogen Substances may enter the body by inhalation, absorption or ingestion. Risk Assessment To have an appreciation of the risks involved in handling cryogenic liquids; consider the hazards created from oxygen deficiency or enrichment caused when gases boil off cryogenic liquids at ratios in the region of 1:700 liquid to gas. For the purposes of risk assessment consider wherever it is possible to spill, absorb or collect water it is also possible to do so with cryogenic liquids, which will have a temperature of below -160 C. Exposed skin is at risk & must be protected. Personal Protective Equipment Non absorbent waterproof gown (No pockets) Appropriate apron Correct gloves Face mask/eye protection Appropriate footwear Additional Safety Precautions Suitable vessels & equipment Product data sheets Adequate ventilation Emergency procedures Rescue procedures Personal or fixed oxygen monitoring Formal operator training Protective Outer Garments These should be of non absorbent waterproof material - materials that will become wet or damp are hazardous as they may become frozen. Laboratory garments should preferably not have pockets to prevent the collection of spilled cryogen. Aprons may prove to be a suitable alternative, covering pockets & areas where spillage may collect.

12 TEMPERATURE SHIELD CRYOGENIC GASES PPE Trousers Avoid trousers with turn-ups in which spilled cryogen could collect. The preference should be for trousers which cover footwear preventing spillage flowing off trousers & into shoes. Apron for Cryogenic Use / Standard EN340 Gloves / Standard EN511 - protection to temperature of -50 c These should be of non absorbent waterproof material. Gloves should be banded securely at the wrist or arm - not of the gauntlet variety. Gloves approved for cryogenic use are available in various forms & sizes from appropriate suppliers. Face Mask / Standard BS EN B After a local risk assessment appropriate PPE such as face masks or goggles should be selected. Footwear It is easily possible for cryogenic liquids to enter shoes from spillage off benches or down the operator s front. Consider footwear that extends up to the ankle allowing the trouser to fit over the footwear. CRYO Steel toe caps may be required subject to APRON local conditions - a full risk assessment should be carried out.

13 CRYOGENIC GASES VESSELS Types 1. Self pressurising storage vessels supplying liquid or gas 2. Non-pressurised vessels (flasks, dewars) Decanting from self pressurising storage vessels at pressures below 3 bar is more efficient than above 3 bar. Use appropriate vessels for the task. Self Pressurising Vessels - Medium/High Pressure Referred to as liquid cylinders. Fitted with internal vaporiser to facilitate the conversion of stored liquid to gas. Typically holds 200 litres of liquid. Supply gas at bar pressure dependent upon the operation & volume required. Self Pressurising Vessels - Low Pressure Self pressurising with a built in pressure raising circuit for vessels up to a maximum of 3 bar pressure. Normal usage is from litres, some have 1,000 litres capacity. Mounted on castor wheels for ease of mobility. Non Pressurised Vessels Range from litres known as working vessels. Constructed from stainless steel with wide neck opening. Supplied with carrying handle & loose fitting lid as a safety device. Larger vessels known as refrigerators are available with up to 500 litre capacity; used for storage of biological specimens in both liquid or gaseous phase.

14 CRYOGENIC GASES VESSELS Typical High Pressure Liquid Cylinder This is an Internal Heat Exchanger 1 that acts to convert the liquid product to a gas via the Gas Use Valve 2 (not present on all vessels) Liquid product is added or withdrawn via the Liquid Withdrawal Valve 3 and tube. 2 This connection must never be removed or exchanged. The Pressure Gauge 4 displays the internal container pressure, not the volume of product contained. The Vent Valve & Line 5 controls a line into the vapour space to vent during the filling process & to remove any unwanted pressure when in use & during storage. Pressure Building Valve 6 and regulator controls the pressure building circuit that is used to create sufficient operating pressure. Relief Devices (Valve & Burst Disc) 7 protect the container from over-pressurisation. Never plug, restrict, Liquid Withdrawal / Fill Valve 4 Pressure Gauge 5 Gas Vent (Trycock) Valve 6 Pressure Build Valve & Regulator 7 Relief Valve 8 Burst disc outlet

15 CRYOGENIC GASES VESSELS Typical Non Pressurised Container - Dewar 0.5 to 50 Litres Dust/Moisture cap Neck Tube Insulation Aluminium Inner Vessel Steel Outer Vessel Vessels and Dewars should be Labelled

16 CRYOGENIC GASES MOVEMENT OF VESSELS Guidance For The Movement of Cryogenic Gases (200 litres or less) All cryogenic storage vessels will produce a small percentage of gas as a result of heat transfer into the vessel. The condition & movement of a vessel may create additional boiling of liquid -producing gas. Release of product may lead to Oxygen deficiency or enrichment Remember: An atmosphere containing less than 18% oxygen is potentially hazardous. Oxygen enrichment levels above just 23% increase the risk of rapid burning. The release of Carbon Dioxide can result in a toxic & Oxygen deficient atmosphere. Spillage of cryogenic liquids leads to cold burns, frostbite & embrittlement of some materials. For the movement of vessels only use approved trolleys that are in good condition & well maintained. Caution Oxygen Depletion! Caution Frostbite!

17 CRYOGENIC GASES MOVEMENT OF VESSELS Handling Vessels Always transport vessels in an upright position. Secure vessels on a pallet, cradle or other device designed for the purpose. Load /unload vessels from a vehicle by using mechanical means such as a crane, fork lift truck or power-assisted tailgate. Do not roll Do not roll PUSH DON T PULL Keep the load close to the body Push with arms bent to absorb stress of sudden changes. The legs are used as the driving force. Back is straight with the body well balanced over the legs. DON T PULL By pulling & leaning away, the weight of the vessel becomes the driving force. Straight arms puts stress on shoulders & back. Your balance is off-centre Your feet may get caught under the vessel. IF THE CONTAINER TIPS OVER - LET IT GO!

18 CRYOGENIC GASES MOVEMENT OF VESSELS Vessel specifically designed for pulling Vessel with handle grip to aid pushing

19 CRYOGENIC GASES MOVEMENT OF VESSELS IN LIFTS Pressurised Vessels Below 60% Rule Vent the vessel to atmosphere in a safe area until the pressure falls below 60% of the relief valve set pressure. Liquid Withdrawal Vessels Below 50% Pressure Rule Dewars fitted with liquid withdrawal devices should be vented to less than half the relief valve set pressure. 90% Fill Dewars should only be filled to 90% of the net capacity to reduce spillage risks. Liquid Stability Close all valves & check the liquid has stabilised using the pressure gauge. Excessive Boil Off Open dewars must be checked for excessive boil off. Leaking Vessels Vessels with leaks from any part of the system or evidence of excessive boil off must not be used. Neck Plug Ensure correct neck plug is fitted before moving the vessel. Ice Formation Do not transport dewars that have ice forming on the outside, this may be a sign of internal damage to the dewar. Warning Do not move vessels in lifts or confined spaces if the pressure increases above 60% of the relief valve set pressure.

20 CRYOGENIC GASES MOVEMENT OF VESSELS IN LIFTS Lifts constitute a confined space. Accompanying cryogenic vessels in lifts is not recommended - where this is unavoidable a full risk assessment should be made refer to BCGA CP27 Para Fan Extraction Where extraction fans are fitted they should be switched on before entry into the lift & during vessel movement. Key Controlled Lifts If movement of vessels in lifts is unavoidable key controlled lifts should be used where available. With this system the lift should not stop between floors & the vessel should be unaccompanied. Standard Lifts Be aware of unauthorised personnel entering lifts containing the cryogenic product - consider the use of additional personnel & use barriers & notices to prevent entry into the lift. Unauthorised Lift Access No unauthorised persons shall be permitted to enter the lift during the transfer of vessels. Oxygen Monitoring The operator should have an operational oxygen monitor in use if accompanying the product. Lift Control The operator should have the ability to control the lift to allow immediate escape at the next available floor in the event of an emergency. Alarms/Telephones The lift should be fitted with an emergency alarm or telephone. Additional Personnel Use the buddy system & have additional personnel outside the lift trained in the hazards of the product & actions to take in the event of an emergency.

21 CRYOGENIC GASES ICE PLUGS Formation Ice plugs may form in the neck of dewars when moisture comes into contact with the cold gas in the neck of the dewar. The resulting ice plug may form a complete seal across the dewar neck, preventing normal venting of gas. In these circumstances liquid boiling off into gas through natural heat seepage into the dewar, creates increasing gas pressure behind the plug of ice. Hazards 1. Pressure build up behind the ice plug may eject it at high velocities. 2. Sufficient pressure may build up to cause the dewar to explode. Prevention Always fit the dewar s protective cap. Ensure caps are in good condition. Do not leave dewars uncapped outdoors & in moist environments. Always ensure that dewars are fully emptied after use. Should an ice plug be found sealing the neck of a dewar immediately evacuate the area. Contact the dewar supplier for specialist advice.

22 TEMPERATURE SHIELD Gas Supplier: Gas Supplier Address: Gas Supplier contact telephone number: IMPORTANT INFORMATION WARNING - This vessel contains a cryogenic liquid at -196 deg. C - Liquid Nitrogen vaporises rapidly to nearly 683 times its liquid volume. - Split Nitrogen can result in cold burns and a reduction of the Oxygen content of the atmosphere nearby. - Only authorised personnel should handle this vessel and its contents. CONTACT Gas Company AT ONCE IF YOU THINK YOU HAVE A PROBLEM MAINTENANCE - REFILL - Nitrogen -N2 (refrigerated liquid) Asphyxiant in high concentrations. Heavier than air. No odour. Do not breathe the gas. COMPRESSED Extremely cold- may cause frost bite GAS Wear suitable gloves and eye /face protection. Keep and use container in a well ventilated place. Use only equipment suitable for nitrogen gas. Follow the suppliers operations instructions. For further safety 2 information see Industrial Gases Data and Safety Sheet UN No 1977 EEC No DO DO NOT Telephone this number to arrange emergency maintenance. Charges will be made for items which are not the responsibility of gas company. Telephone this number to arrange additional deliveries with gas company outside your pre-arranged schedule supply. DEWAR Nominal Capacity Litres The use of this vessel and the critical parts of its operation and maintenance should be fully understood by the user. Refer to the manufacturers literature for liquid withdrawal device valves and safety valves information. CRYOGENIC GASES DECANTING PROCEDURE Decanting procedure from a portable pressurised vessel to a dewar up to 0.5bar Supply Vessel Checks: Regular in-service examination received and within test Appropriate location; stable & secure Check for damage & inappropriate ice formation Correctly labelled for gas type (Nitrogen service) Transfer hose & filling equipment clean & free from damage Fit phase separator where necessary Defective vessels & hose should be removed from service & reported to maintenance Check liquid level is sufficient Check pressure gauge reading is 1 to 1.5 bar If above 1.5 bar consider venting down gas pressure in a safe area outdoors If pressure is insufficient to decant consider opening pressure build circuit 5 Ensure full PPE is worn CRYO APRON 1 9 NITROGEN Keep the vessel upright and clear from obstructions. Site in a safe area to prevent damage. Ensure adequate ventilation at all times. Where a liquid withdrawal device is fitted check connections for leaks. Use only the manufacturer s recommended methods to move cylinders. Wear Personal Protective Equipment. Where a liquid withdrawal device is fitted ensure all valves are closed securely when the vessel is not in use. Seek immediate medical assistance in the event of direct contact with cold liquid. Tamper with safety relief devices Carry out any repairs or modifications to any part of the vessel. Fit liquid withdrawal devices to vessels which are not marked as suitable for such devices. Operate withdrawal devices above.05 bar. Allow oil or grease to come into contact with the vessel or withdrawal device. Permit direct flame or heating devices near the vessel. Transfer liquid into vessels other than those constructed for the purpose. Enter vapour clouds. Take risks At no time must the vessel and dewar be left unattended during the filling procedure

23 CRYOGENIC GASES DECANTING PROCEDURE Receiving Vessel (Dewar) Checks: In good condition Undamaged neck Insulating dust/moisture cap present/in place 7 Labelled for gas usage service 8 A liquid withdrawal device should not be fitted Filling Procedure: Place the end of the transfer hose into the open neck of the dewar Open the fill valve slightly and purge air from the hose 9 Just as the liquid appears, feed the transfer hose further into the dewar Control the decant allowing sufficient time for the dewar to cool Minimise mists and vapours through control of the fill valve Avoid inhaling mist and vapour clouds where possible When the dewar is full, close the fill valve on the vessel Slowly remove the transfer hose and allow residual liquid and gas within the hose to vent off Store hose correctly on vessel Replace dust/moisture cap on the dewar Return vessel to appropriate location Do not fill if: The dust/moisture cap has fallen into the dewar The dewar contains ice/water or excessive frosting is present around the neck The dust/moisture cap is missing, do not use unapproved bungs, seals or rags as stoppers 4 LIQUID NITROGEN 8 7

24 CRYOGENIC GASES SPILLAGE During filling never leave the vessel unattended Cryogenic Spillage Risk Considerations Refer to BCGA CP27, CP28 & CP30 for calculating gas volumes resulting from spills or leaks. Consider the effect of heavier than air gases permeating into basements, cellars, stairwells, under floors & pits. Ensure that staff not directly involved with the use of cryogenic gases are aware of the dangers of affecting unprotected rescues in cryogenic & gas incidents. Carry out regular practice drills for such eventualities. Spillage Emergency Actions Sound the alarm & evacuate adjacent areas which may be affected by evolved gas. Restrict gas escape by closing doors. Call the Emergency Services. Do not attempt to enter a gas-filled room without specialist training in breathing apparatus rescue techniques. Prevent people entering mists, vapours & clouds. Only if safe to do so, consider opening exterior doors & windows to allow ventilation & encourage evaporation of the liquid & gas - do not undertake this if it compromises immediate evacuation. After any Spillage Check floors & equipment for embrittlement & other damage caused by extreme low temperatures. Give special consideration to areas under floors where maintenance or other human access may be required which could contain heavier than air gases - consider testing these areas with Oxygen monitoring equipment before declaring safe. Consider using Oxygen monitoring equipment to check Oxygen levels before declaring the area safe.

25 CRYOGENIC GASES STORAGE Cryogenic gases & containers should be stored: separately from all other gas types in a well-ventilated area protected from excessive heat protected from mechanical shock away from naked flames or incandescent material away from any form of likely ignition Maintain a register of all vessels & equipment. Vessels kept upright with correct labelling to identify contents. The area should have appropriate warning signage. Access restricted to trained personnel wearing appropriate PPE. Emergency procedures should be prepared, implemented & practiced.

26 DRY ICE SOLIDIFIED CARBON DIOXIDE (CO2) Dry ice is solidified Carbon Dioxide (CO2) at -78 C (-109 F). It does not melt but sublimates releasing CO2 which is substantially heavier than air. Vapour/gas is colourless. May have a slightly pungent odour. Due to the formation of carbonic acid in moisture it may have an acidic or bitter taste. Atmospheres above 0.5% are considered hazardous. (See Page 56) In confined inadequately ventilated spaces, it can displace air, causing asphyxiation. May cause severe cold burns on contact with the skin. 10kg of dry ice produces approximately 4.5 cubic metres of gas. Safety Precautions Ensure adequate ventilation. Avoid contact with skin & eyes. Handle with suitable PPE i.e. insulated gloves; safety glasses. Do not ingest. Dry Ice may be manufactured in the form of pellets, slices or blocks -use in the form suitable for purpose, do not saw or hammer a block into smaller pieces. Do not store in sealed (air-tight) containers or coolers which may result in a rupture or explosion of the container from over pressurisation.

27 DRY ICE SOLIDIFIED CARBON DIOXIDE (CO2) Transportation Ensure load is secure. Preferably transport in vehicles where driver is isolated from load compartment, where this is not possible: Ensure adequate ventilation Leave windows open Disposal Always ensure that Dry Ice is disposed in a safe place. Away from areas accessible to the general public. Allow to sublimate to the atmosphere in a well-ventilated area where no build up of Carbon Dioxide vapour can occur. Identification of Liquid & Vapour CO2 Cylinders NEW COLOURS NEW COLOURS OLD COLOURS OLD COLOURS Liquid withdrawal CO2 cylinders have a dip tube inside the cylinder designed to draw liquid off - this is indicated by the white stripe.

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29 Independently assessed and approved training for users of compressed & cryogenic gases Proactive Gas Safety works with organisations whose concern is the safety of employees and contractors using potentially hazardous compressed gases and equipment. We provide you with the knowledge and tools to ensure a safe working environment so that risk can be minimised. Oxy-fuel Industrial Laboratory Cryogenic Proactive Gas Safety Lt d Tel: admin@pgstr aining.co m m RECOGNISED PARTNER