Safe Handling and Use of Liquid Nitrogen 2006 Americana Safety Associates, Inc

Safe Handling and Use of Safe Handling and Use of Liquid NitrogenLiquid Nitrogen

2006 Americana Safety Associates, Inc.

2006 Americana Safety Associates, Inc.2006 Americana Safety Associates, Inc. 22

Safe Handling and Use of Safe Handling and Use of Liquid NitrogenLiquid Nitrogen

This awareness training is intended for This awareness training is intended for laboratory users of Liquid Nitrogen.laboratory users of Liquid Nitrogen.

The training covers Oxygen Deficiency, The training covers Oxygen Deficiency, Handling of Liquid Nitrogen, Personal Handling of Liquid Nitrogen, Personal Protective Equipment, Emergencies, and Protective Equipment, Emergencies, and Trouble Shooting.Trouble Shooting.

All new and current laboratory personnel should All new and current laboratory personnel should review this information and refer to it review this information and refer to it periodically.periodically.


Manufacture of Liquid GasesManufacture of Liquid Gases

Normal air is cooled.Normal air is cooled.As the temperature drops, the gases will As the temperature drops, the gases will drop out separately, according to their drop out separately, according to their boiling points. Liquid nitrogen will drop boiling points. Liquid nitrogen will drop out at –320 F (-196 C)out at –320 F (-196 C)The liquified gas is collected.The liquified gas is collected.The liquid boils violently in trying to get The liquid boils violently in trying to get back to its normal gaseous state. back to its normal gaseous state.


78% of Atmosphere78% of Atmosphere

Colorless, Odorless, Tasteless and NontoxicColorless, Odorless, Tasteless and Nontoxic

Boils at -320 degrees Fahrenheit (-196 C)Boils at -320 degrees Fahrenheit (-196 C)

Non-FlammableNon-Flammable

WILL NOT SUPPORT LIFEWILL NOT SUPPORT LIFE

Gas is slightly lighter than airGas is slightly lighter than air

Characteristics of NitrogenCharacteristics of Nitrogen


Oxygen DeficiencyOxygen Deficiency

Liquid nitrogen, when returned to the Liquid nitrogen, when returned to the gaseous state, can displace oxygen from the gaseous state, can displace oxygen from the air and can create an oxygen-deficient air and can create an oxygen-deficient atmosphere under the right conditions.atmosphere under the right conditions.

It may be prudent to install oxygen It may be prudent to install oxygen monitors in areas where liquid nitrogen is monitors in areas where liquid nitrogen is stored and ventilation is minimal.stored and ventilation is minimal.


Characteristics of Oxygen DeficiencyCharacteristics of Oxygen Deficiency

Physiological Effects:Physiological Effects:– Asphyxia develops slowly as the oxygen Asphyxia develops slowly as the oxygen

content of air is gradually reduced from 21%. content of air is gradually reduced from 21%. – The victim will not be aware of a problem and The victim will not be aware of a problem and

generally will not recognize the symptoms of generally will not recognize the symptoms of gradual asphyxia from decreasing oxygen gradual asphyxia from decreasing oxygen levels.levels.


Characteristics of Oxygen DeficiencyCharacteristics of Oxygen Deficiency

Oxygen Deficiency Precautions:Oxygen Deficiency Precautions:– All cryogenic liquids should be used and stored All cryogenic liquids should be used and stored

in well-ventilated areas.in well-ventilated areas.– High concentrations of nitrogen reduce the High concentrations of nitrogen reduce the

breathable oxygen in the air. breathable oxygen in the air. – Filling between containers, leaking valves, and Filling between containers, leaking valves, and

liquid tank venting are some examples that liquid tank venting are some examples that could lead to an oxygen deficient atmosphere.could lead to an oxygen deficient atmosphere.


Characteristics of Characteristics of Cryogenic Liquid NitrogenCryogenic Liquid Nitrogen

Primary HazardsPrimary Hazards– AsphyxiationAsphyxiation– Potential for rupture of containers, pipelines, or Potential for rupture of containers, pipelines, or

systems. When liquid or even cold vapor is systems. When liquid or even cold vapor is trapped between valves there is the potential to trapped between valves there is the potential to cause a pressure buildup to a point of violent cause a pressure buildup to a point of violent rupture to a container or piping. (Reliable rupture to a container or piping. (Reliable pressure relief devices are used to prevent this)pressure relief devices are used to prevent this)


Liquid Nitrogen FactsLiquid Nitrogen Facts

Boiling Point -320 °F (-196 °C)Boiling Point -320 °F (-196 °C)

Volume Expansion Rate = 696Volume Expansion Rate = 696


Comparison to Other Comparison to Other Liquified (Cryogenic) Gases Liquified (Cryogenic) Gases

GasGas NN22 OO22 ArAr HH22 HeHe

BP, °FBP, °F -320-320 -297-297 -303-303 -423-423 -452-452

BP, °CBP, °C -196-196 -183-183 -186-186 -253-253 -268-268

Volume Volume ExpansionExpansion 696696 860860 696696 850850 745745


Example

1 cubic foot of liquid nitrogen will expand 1 cubic foot of liquid nitrogen will expand to 696 cubic feet of 100% gaseous nitrogen to 696 cubic feet of 100% gaseous nitrogen at 70° F.at 70° F.

The nitrogen gas can displace the oxygen in The nitrogen gas can displace the oxygen in the area, leading to asphyxiation.the area, leading to asphyxiation.

This is why cryogenic liquids should This is why cryogenic liquids should always be stored in well-ventilated spaces.always be stored in well-ventilated spaces.


Handling Liquid NitrogenHandling Liquid Nitrogen

Always read the container label prior to use.Always read the container label prior to use.

Cryogenic liquid containers must always be Cryogenic liquid containers must always be stored in the upright position.stored in the upright position.

Cryogenic liquids should not be handled in open Cryogenic liquids should not be handled in open pail-type containers or in unapproved dewars.pail-type containers or in unapproved dewars.

Transfer of liquid into warm lines or containers Transfer of liquid into warm lines or containers must be done slowly to prevent thermal shock and must be done slowly to prevent thermal shock and possible buildup of pressure.possible buildup of pressure.



Precautions:Precautions:– Always wear safety equipment, including Always wear safety equipment, including

cryogenic gloves, and eye and face protection.cryogenic gloves, and eye and face protection.– High concentrations of escaping gas should not High concentrations of escaping gas should not

be allowed to collect in an enclosed area.be allowed to collect in an enclosed area.– Avoid prolonged breathing of cryogenic Avoid prolonged breathing of cryogenic liquid liquid

vaporsvapors . . – TUNL Provides cryogenic gloves and face TUNL Provides cryogenic gloves and face

shields for your protection. shields for your protection.



Prior to use, ensure the fittings on the regulator Prior to use, ensure the fittings on the regulator match the fittings on the liquid containermatch the fittings on the liquid container

Never use adaptorsNever use adaptors

Never attempt to change or remove any fittingsNever attempt to change or remove any fittings


Containers for Holding Liquid Containers for Holding Liquid Nitrogen Nitrogen AfterAfter Dispensing Dispensing

ThermosThermos®® bottles are approved containers bottles are approved containers

Use only containers specially designed to Use only containers specially designed to hold liquid nitrogen. Check with the hold liquid nitrogen. Check with the manufacturer of the container to ensure it is manufacturer of the container to ensure it is approved for holding liquid nitrogen.approved for holding liquid nitrogen.


Different Types of Liquid CylindersDifferent Types of Liquid Cylinders


Cryogenic Liquid ContainersCryogenic Liquid Containers(aka Liquid Cylinders)(aka Liquid Cylinders)

Advantages:Advantages:

Contain large volumes of gasContain large volumes of gas

Provides a source of Cryogenic Liquids which can Provides a source of Cryogenic Liquids which can be easily handledbe easily handled

Two general types:Two general types:

Low PressureLow Pressure: For dispensing of : For dispensing of liquid liquid only.only.

High PressureHigh Pressure: For dispensing of liquid : For dispensing of liquid andand gas gas


Construction of Liquid ContainersConstruction of Liquid Containers

Liquid containers are Liquid containers are made made somewhatsomewhat like like ThermosThermos®® bottles with bottles with a vacuum space and a vacuum space and special insulation, but special insulation, but they are they are notnot Thermos Thermos bottlesbottles®®

Annular Space


Construction of Liquid ContainerConstruction of Liquid Container

Even with the vacuum and insulation, heat Even with the vacuum and insulation, heat leaks in to the cylinder causing the leaks in to the cylinder causing the cryogenic liquid to vaporize and build cryogenic liquid to vaporize and build pressure. pressure.

The vaporization rate will depend on The vaporization rate will depend on several factors including the product itself, several factors including the product itself, ambient temperature, condition of the ambient temperature, condition of the cylinder’s vacuum, etc.cylinder’s vacuum, etc.


Pressure Relief DevicesPressure Relief Devices

The liquid-to-gas conversion The liquid-to-gas conversion rate is about 2.3% per day rate is about 2.3% per day under perfect conditions, so under perfect conditions, so the actual vaporization rate the actual vaporization rate experienced can vary.experienced can vary.If gas product is not used, If gas product is not used, pressure will build until it is pressure will build until it is released by a released by a control valvecontrol valve..Note that this is a high Note that this is a high pressure container, with the pressure container, with the gauge marked for 350 psig.gauge marked for 350 psig.


Pressure Relief DevicesPressure Relief Devices

Hearing a slight hiss from a liquid cylinder Hearing a slight hiss from a liquid cylinder is usually the normal operation of its is usually the normal operation of its pressure relief device.pressure relief device.Liquid cylinders should always be stored Liquid cylinders should always be stored and used in areas with appropriate natural and used in areas with appropriate natural or mechanical ventilation.or mechanical ventilation.Never adjust, block, plug or attempt to Never adjust, block, plug or attempt to repair anything on a liquid cylinder.repair anything on a liquid cylinder.


Liquid-to-Gas ConversionLiquid-to-Gas Conversion

Since liquid is converted to gas at about Since liquid is converted to gas at about 2.3% per day even under ideal container 2.3% per day even under ideal container conditions, if the liquid is not used conditions, if the liquid is not used regularly, the vessel will be empty in a regularly, the vessel will be empty in a certain amount of time.certain amount of time.

It is important to estimate your use so the It is important to estimate your use so the liquid will not be wasted.liquid will not be wasted.


Content Gauge on Liquid CylindersContent Gauge on Liquid Cylinders

The container contents gauge is a float-type The container contents gauge is a float-type liquid level sensor that indicates the level of liquid level sensor that indicates the level of the liquid.the liquid.

The gauge is an indication of approximate The gauge is an indication of approximate container content, and should not be used for container content, and should not be used for judging the judging the weight weight of the container. of the container.

Containers are always filled by Weight!Containers are always filled by Weight!



Cryogenic Liquid ContainersCryogenic Liquid Containers(Liquid Cylinders)(Liquid Cylinders)

Make sure you know the type of container Make sure you know the type of container that is used by your lab!!that is used by your lab!!

Low pressure is used only for the delivery Low pressure is used only for the delivery of of LIQUIDLIQUID, not gas, not gas

It’s operating pressure is 22 psigIt’s operating pressure is 22 psig

TUNL uses ONLY this type!TUNL uses ONLY this type!


Cryogenic Liquid Containers Cryogenic Liquid Containers (Liquid Cylinders)(Liquid Cylinders)

Head pressureHead pressureResults when heat leaks into the container;Results when heat leaks into the container;The safety valve will periodically release this The safety valve will periodically release this pressure;pressure;If the safety valve malfunctions, a backup disk If the safety valve malfunctions, a backup disk will rupture and relieve the pressure; andwill rupture and relieve the pressure; andThe rupture of the backup disk will produce a loud The rupture of the backup disk will produce a loud sound and may release a large quantity of liquid sound and may release a large quantity of liquid and gas. and gas. Evacuation of the area is required to Evacuation of the area is required to prevent asphyxiationprevent asphyxiation..


Low Pressure Liquid Low Pressure Liquid Container ComponentsContainer Components

Liquid Withdrawal Valve:Liquid Withdrawal Valve:– Liquid is withdrawn through this valveLiquid is withdrawn through this valve

Pressure Gauge:Pressure Gauge:– Displays internal pressure of the containerDisplays internal pressure of the container

Contents Gauge:Contents Gauge:– A float-type liquid level gauge-indicates approximate A float-type liquid level gauge-indicates approximate

level of liquidlevel of liquid




Vent ValveVent Valve– Primarily used in the fill process to vent the Primarily used in the fill process to vent the

vapor space while filling. Can be used to vent vapor space while filling. Can be used to vent unwanted pressure during storage and use.unwanted pressure during storage and use.

Pressure Relief Devices (2)Pressure Relief Devices (2)– Protect vessel from over-pressurizationProtect vessel from over-pressurization

Re-seating spring-loaded relief valve releases at 22 psigRe-seating spring-loaded relief valve releases at 22 psig

Burst disk rated to protect the inner vesselBurst disk rated to protect the inner vessel



Outlet RestraintsOutlet Restraints– These are to prevent the dangerous practice of changing These are to prevent the dangerous practice of changing

outlet connections at user sites. These restraints may outlet connections at user sites. These restraints may be twist ties, wire, or other.be twist ties, wire, or other.

– Removal of these restraints will void all product Removal of these restraints will void all product warranties!!warranties!!

– Changing outlet connections is an extremely dangerous Changing outlet connections is an extremely dangerous practice and can result in serious injury or death if an practice and can result in serious injury or death if an incompatible product is introduced into a user’s system.incompatible product is introduced into a user’s system.


Warning !Warning !

Never plug, restrict, or remove any relief device.Never plug, restrict, or remove any relief device.

Never attempt to cap or seal a venting relief Never attempt to cap or seal a venting relief device in any way.device in any way.

Ice or frost buildup on a pressure relief valve can Ice or frost buildup on a pressure relief valve can be removed with a damp cloth. (Wear proper be removed with a damp cloth. (Wear proper Personal Protective Equipment (PPE) when Personal Protective Equipment (PPE) when removing the frost.)removing the frost.)

Contact and TUNL Staff Member for assistance! Contact and TUNL Staff Member for assistance! Do NOT attempt repairs by yourself!Do NOT attempt repairs by yourself!


Moving Liquid CylindersMoving Liquid Cylinders

Liquid cylinders range in different Liquid cylinders range in different weights and sizes. They are weights and sizes. They are heavyheavy and cumbersome, especially when and cumbersome, especially when filled with liquid nitrogen.filled with liquid nitrogen.They may require two people to They may require two people to handle in order to do so safely.handle in order to do so safely.Containers can cause crushing injury Containers can cause crushing injury to the feet. Wear proper shoes. to the feet. Wear proper shoes. Tennis shoes and open toed shoes are Tennis shoes and open toed shoes are not proper foot protection!!not proper foot protection!!Contact any Technical Staff Member Contact any Technical Staff Member for assistance if you need a cylinder for assistance if you need a cylinder moved.moved.


Elevator TransportElevator Transport

Use freight elevator if possible.Use freight elevator if possible.

If a passenger elevator is used, it should be locked If a passenger elevator is used, it should be locked out to all other users.out to all other users.

Do not transport a liquid container at any time in Do not transport a liquid container at any time in an elevator with any other personnel in the car an elevator with any other personnel in the car

unless theyunless they have a supplied air respirator.have a supplied air respirator.


EmergenciesEmergencies

If there is a large spill or rupture of a container, If there is a large spill or rupture of a container, call 911, warn others in building. call 911, warn others in building.

Evacuate! There may be oxygen deficiency in Evacuate! There may be oxygen deficiency in the area of the spill.the area of the spill.

If there is injury to the body from liquid nitrogen, If there is injury to the body from liquid nitrogen, seek immediate medical assistance.seek immediate medical assistance.


EmergenciesEmergencies

If liquid is splashed in the eyes, flush with If liquid is splashed in the eyes, flush with water for at least 15 minutes. Seek water for at least 15 minutes. Seek immediate medical attention. immediate medical attention. Call 911Call 911Skin contact may cause frostbite and burns. Skin contact may cause frostbite and burns. Soak affected part in tepid water and seek Soak affected part in tepid water and seek immediate medical attention. immediate medical attention. Call 911Call 911Skin contact is a medical emergency. Lack Skin contact is a medical emergency. Lack of prompt medical attention may result in of prompt medical attention may result in amputation. amputation. Call 911Call 911


If you fill cryogenic liquids, the possibility of If you fill cryogenic liquids, the possibility of cryogenic liquid coming in contact with the skin is cryogenic liquid coming in contact with the skin is reduced with the use of proper Personal Protective reduced with the use of proper Personal Protective Equipment (PPE).Equipment (PPE).– Full Face Shield with safety glassesFull Face Shield with safety glasses

– Heavy, Heavy, Loose FittingLoose Fitting leather or Cryogenic Gloves leather or Cryogenic Gloves

– Long Sleeve Shirt, or Arm ProtectionLong Sleeve Shirt, or Arm Protection

– Pants should be cuff-lessPants should be cuff-less

– Do not tuck pants into shoes, boots.Do not tuck pants into shoes, boots.

Personal Protective Equipment (PPE) Personal Protective Equipment (PPE)

for Cryogenicsfor Cryogenics


Liquid WithdrawalLiquid Withdrawal

Caution!Caution!– Always wear a full face shield, goggles, leather or Always wear a full face shield, goggles, leather or

cryogenic gloves, safety shoes, and aprons when cryogenic gloves, safety shoes, and aprons when transferring liquid. transferring liquid.

– Ensure that the liquid cannot collect in pants cuffs or Ensure that the liquid cannot collect in pants cuffs or travel down into shoes. Do not tuck cuffs into pants! travel down into shoes. Do not tuck cuffs into pants! Cuff gloves over sleevesCuff gloves over sleeves..

– Transfer of liquids at pressures higher than 22 psig into Transfer of liquids at pressures higher than 22 psig into open vessels such as small dewars can lead to excessive open vessels such as small dewars can lead to excessive splashing. This could result in injury from freezing of splashing. This could result in injury from freezing of the body part.the body part.


Liquid HeliumLiquid Helium

Super coldSuper cold at - 452 F (- 268 C) at - 452 F (- 268 C)

Special container needed for more insulationSpecial container needed for more insulation

Personal Protective Equipment (PPE) extremely Personal Protective Equipment (PPE) extremely importantimportant

Like Liquid Nitrogen, an inert gasLike Liquid Nitrogen, an inert gas

Will not support life or combustionWill not support life or combustion

Asphyxiation potential same as Liquid Nitrogen Asphyxiation potential same as Liquid Nitrogen

Be SafeBe Safe

Thank you for your participationThank you for your participation

Documents

Safe Handling and Use of Liquid Nitrogen 2006 Americana Safety Associates, Inc