T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A

Safe Handling and Use of Liquid Nitrogen and Dry Ice

From: Wikimedia Commons. http://upload.wikimedia.org/wikipe dia/commons/d/df/Liquid_nitrogen_ portable_tank_pl.jpg

From: Wikimedia Commons. http://commons.wikimedia.org/wiki/File:Dry_Ice_Sublimation_2.jpg

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A Topics to be Covered Course Method

• Physical and Chemical • Proper Personal Protective • Read through sides Properties of Nitrogen and Equipment (PPE) Dry ice • Safely Moving Liquid • Take quiz • Hazards Cylinders • Safe Handling Liquid • Emergencies • Work safely with liquid nitrogen, dry ice and other Nitrogen and Dry Ice • Elevator Transport cryogenics • Liquid Cylinder • Trouble Shooting Construction • Filling Cryogenic Dewars

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A Properties of Nitrogen

CHEMICAL & PHYSICAL • 78% of Atmosphere

PROPERTIES • Colorless, Odorless, Tasteless and Nontoxic

• Boils at -196 C

• Non-Flammable

• Gas is slightly lighter than air

1 Properties of Dry Ice T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A

• Tasteless and odorless • No residue as solid sublimes HAZARDS • Germ and bacteria-free • Non-poisonous • Non-flammable • Heavier than air • At room temperature Dry Ice sublimates at 14%/hr* • Temperature -78.5 C

* H.L. Gibbons, “Carbon Dioxide Hazards in General Aviation,” Aviation, Space, and Environmental Medicine Vol. 48, No. 3 (March 1977): 261-263.

Hazards of Cryogenic Gasses Hazards - Asphyxiation

• Primary Hazards

– Asphyxiation • Liquid nitrogen and CO 2, when returned to the gaseous – Contact burns state, can displace oxygen from the air and can create an – Shattering of receptacles on contact oxygen-deficient atmosphere under the specific – Potential for pressure rupture of containers, conditions. pipelines, or systems. – Musculoskeletal lifting injuries • It may be prudent to install oxygen monitors in areas where liquid nitrogen or dry ice is stored and ventilation is minimal.

Physical Properties of Liquefied (Cryogenic) Gasses Example:

Gas N2 O2 Ar H2 He CO 2 • 1 litre of liquid nitrogen will expand to 696 litres of 100% gaseous nitrogen at 25 ° C

BP, °F -320 -297 -303 -423 -452 109.3 • The nitrogen gas can displace the oxygen in the area, leading to asphyxiation BP, -196 -183 -186 -253 -268 -78.5 °C • This is why cryogenic liquids should always be stored Volume in well-ventilated spaces Expansion 696 860 696 850 745 540

2 Oxygen Deficiency Oxygen Deficiency

• Normal Concentrations: • Physiological Effects:

– The normal oxygen concentration in air is about – Asphyxia develops slowly as the oxygen 21% by volume. This provides for a safe working content of air is gradually reduced from 21%. environment with respect to the oxygen required to support life. – The victim will not be aware of a problem and generally will not recognize the symptoms of – Oxygen concentration below 19.5% is gradual asphyxia from decreasing oxygen considered an oxygen deficient environment levels.

Oxygen Deficiency Liquid Nitrogen Burn from Unprotected Spill

• Oxygen Deficiency Precautions:

– All cryogenics should be used and stored in well- ventilated areas

– High concentrations of nitrogen and carbon dioxide reduce the breathable oxygen in the air

– Filling between containers, leaking valves, and liquid tank venting are some examples that could lead to an oxygen deficient atmosphere

Musculoskeletal Injury Hazard T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A

SAFE HANDLING PROCEDURES

• Two people should lift Dewars greater than 20 litre capacity

3 Handling Liquid Nitrogen Handling Liquid Nitrogen • Always read the container label prior to use • Avoid rough handling of liquid containers • Cryogenic liquid containers must always be stored in the upright position • A cold outside jacket indicates a loss of vacuum-Contact supervisor or vendor • Cryogenic liquids should not be handled in open pail- type containers or in unapproved dewars – Use approved containers • Liquid cylinders should only be moved with proper handling equipment. • Transfer of liquid into warm lines or containers must be done slowly to prevent thermal shock and possible buildup of pressure.

Handling Dry Ice Handling Liquid Nitrogen

• Prior to use, ensure the fittings on the regulator match • Always store in a well ventilated room the fittings on the liquid container • Always wear insulated gloves when handling dry ice – do not use latex gloves • Never use adaptors • Wear safety glasses and lab coat • Never attempt to change or remove any fittings • Prevent contact with uncovered skin

• Dispose unwanted dry ice in a fume hood

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A Lab Use: Containers for Holding Liquid Nitrogen After Dispensing LIQUID CYLINDERS • Use only containers specially designed to hold liquid nitrogen

• Check with the manufacturer of the container to ensure it is approved for holding liquid nitrogen

4 Different Types of Liquid Cryogenic Liquid Cylinders Containers • Contain large volumes of liquid / gas

• Two general types:

– Low Pressure • For dispensing of liquid only

– High Pressure • For dispensing of liquid and gas

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A Construction of Liquid Containers

• Liquid containers are made somewhat like LIQUID CYLINDER Thermos ® bottles with a vacuum space and CONSTRUCTION, STORAGE & special insulation USE • But they are not Thermos bottles ®

Annular Space

Construction of Liquid Container Pressure Relief Devices • The liquid-to-gas conversion rate • Even with the vacuum and insulation, heat leaks in to is about 2.3% per day under the cylinder causing the cryogenic liquid to vaporize perfect conditions, so the actual and build pressure. vaporization rate experienced can vary. • The vaporization rate will depend on several factors including: • If gas product is not used, – the product itself pressure will build until it is – ambient temperature released by a control valve. – condition of the cylinder’s vacuum, – etc… • Note that this is a high pressure container, with the gauge marked for 350 psig.

5 Pressure Relief Devices Pressure Relief Device Formula • Hearing a slight hiss from a liquid cylinder is usually • Pressure relief devices are prescribed based on the the normal operation of its pressure relief device. following formula for vacuum-insulated cylinders

• Liquid cylinders should always be stored and used in (Cylinder service pressure X 1.25) – 15psi = areas with appropriate natural or mechanical ventilation Maximum Pressure Relief Device Rating (psi)

• Never adjust, block, plug or attempt to repair anything on a liquid cylinder

Items that are usually checked by the vendor before filling a liquid cylinder Items that are usually checked by the vendor after filling a liquid cylinder

• Visual Inspection • Valve Inspection • Pressure relief valve inspection • Vent valve • Safety burst / rupture disc inspection • Vacuum casing burst / rupture disk inspection • Gross weight • Tare weight

• Net weight

Liquid-to-Gas Conversion Cryogenic Liquid Containers - Storage in Cold Rooms • Contrary to popular belief, storage of liquid • Liquid converts to gas at about 2.3% per day even containers in cold rooms will not slow down the under ideal container conditions, if the liquid is not liquid to gas conversion used regularly, the vessel will be empty in a certain amount of time • Storage in cold rooms can actually create an oxygen deficient atmosphere if the room does not • It is important to estimate your use so the liquid have adequate ventilation to remove the nitrogen will not be wasted gas generated

• If there is a concern regarding oxygen deficiency in these areas, oxygen deficiency alarms should be installed

6 Cryogenic Liquid Containers Cryogenic Liquid Containers • Always check the type of container that is being delivered or before use • Make sure you know the type of container that is used by your lab!! • One lab had ordered low pressure and received high pressure by mistake. – The lab personnel assumed it was low pressure and • Low pressure is used only for the delivery of LIQUID, not began to use it. This could have resulted in an unsafe gas condition. Low pressure has an operating pressure of 22 – Its operating pressure is 22 psig psig!!!

• High pressure operates at 230 psig or above. Check the pressure gauge to determine the type of container

Low Pressure Liquid Container • Vent Valve Components – Primarily used in the fill process to vent the vapor • Liquid Withdrawal Valve space while filling. Can be used to vent unwanted pressure during storage and use – Liquid is withdrawn through this valve

• Pressure Relief Devices (2) • Pressure Gauge – Protect vessel from over-pressurization – Displays internal pressure of the container – Re-seating spring-loaded relief valve releases at 22 psig • Contents Gauge – Burst disk rated to protect the inner vessel – A float-type liquid level gauge-indicates approximate level of liquid

Low Pressure Liquid Container Components • Outlet Restraints – These are to prevent the dangerous practice of changing outlet connections at user sites. These restraints may be twist ties, wire, or other. – Changing outlet connections is an extremely dangerous practice and can result in serious injury or death if an incompatible product is introduced into a user’s system

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

7 Content Gauge on Liquid Cylinders - Content Gauge

• The container content gauge is a float-type liquid level sensor that indicates the level of the liquid

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

• Containers are filled by Weight.

Cryogenic Liquid Containers - Cryogenic Liquid Containers – Head Pressure Signage • Results when heat leaks into the container • The safety valve will periodically release this pressure • Caution Signs should be posted in the • If the safety valve malfunctions, a backup disk will area warning that liquid nitrogen is being rupture and relieve the pressure stored and used. • The rupture of the backup disk will produce a loud sound and may release a large quantity of liquid and gas. • Evacuation of the area is required to prevent asphyxiation

Warning!!!! T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A

• Never plug, restrict, or remove any relief device MOVING LIQUID CYLINDERS • Never attempt to cap or seal a venting relief device in any way • Ice or frost buildup on a pressure relief valve can be removed with a damp cloth. – Wear proper Personal Protective Equipment (PPE) when removing the frost.

8 Moving Liquid Cylinders Moving Liquid Cylinders • Never try to roll liquid • Liquid cylinders range in different weights and sizes. cylinders by using the They are heavy and cumbersome, especially when Liquid Level Gauge tube. filled with liquid nitrogen • Note the proper stance and • They may require two people to handle in order to do use of the cylinder’s halo so safely ring for moving.

• Containers can cause crushing injury to the feet. Wear proper shoes. Tennis shoes and open toed shoes are not proper foot protection!!

Transport Moving Liquid Cylinders • Use the specially designed and designated • Always use the specially designed cylinder handcart cart when moving liquid cylinders

• Do not roll, either vertically or horizontally • If the cart has a height adjustment for different cylinders, be sure it’s adjusted to the proper height. • Push, Don’t Pull

• If the container tips over, let it go

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A Elevator Transport of Liquid Nitrogen

• Immediate oxygen depletion ELEVATOR TRANSPORT if spilled

• Use freight elevator if possible

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

• Do not transport cryogenics at any time in an elevator with any other personnel in the car unless they have a supplied air respirator

9 Elevator Transport of Elevator Transport of Dry Ice Liquid Nitrogen • When a container has been placed on an elevator, the • Calculation of oxygen displacement: elevator must travel between floors unoccupied – 1 litre of DI @ 14% = 140 cc/hr – Expands to 540 x 140 = 75600 cc/hr • All elevator doors must be manned to prevent entry – Elevator = 2m x 2.5m x 3m = 15 x10 6 cc

• Person/s must be stationed at all “in-between” floors to – 75600/15,000,000 = 0.5% concentration of CO 2 prevent riders from entering elevator after one hour in elevator

• The sender should remain outside the elevator and activate it to the desired floor. Another person should • Not an immediate risk of oxygen be available on the receiving floor to take the liquid depletion…personnel permitted in elevator container off the elevator at its destination

The TLV (and PEL) assigned to carbon dioxide is 5000 ppm (NIOSH has recommended a Standard of 1.0% or 10 000 ppm for a 10-hr work shift with a ceiling of 3.0% or 30 000 ppm for any 10-min period). These concentrations are an expression of good practice rather than a line between "safe" and "deadly."

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A Emergencies

EMERGENCY RESPONSE • If there is a large spill or rupture of a container, call 911 and warn others in building

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

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

Emergencies T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A

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

First Aid - Call 7-8111

10 Personal Protective Personal Protective Equipment Equipment (PPE) for Cryogenics (PPE) for Cryogenics

Hazards can be controlled in the following ways and in the following order: • If there is any chance of contact with cryogenics, or if handling / transporting, wear the following PPE 1. Minimize/Eliminate/Substitute – Full Face Shield with safety glasses • Due to the potential for splashing & shattering 2. Engineering/Task Design – Heavy, Loose Fitting leather or Cryogenic Gloves 3. Administrative/Work Procedures • Protection for skin 4. Personal Protective Equipment (PPE) – Long Sleeve Shirt, or Arm Protection • Protection for skin

PPE is the last line of defense, and should never • Continued… be your first means of controlling a risk.

Personal Protective Equipment (PPE) for Liquid Dispensing Cryogenics

• Required PPE continued…

– Pants should be cuff-less

• Cuffs can hold liquids / vapours

– Do not tuck pants into shoes, boots

– Proper laboratory footwear

• Footwear that does not completely cover the surface of your foot does not provide adequate protection

• The mesh on running shoes does not provide enough protection for your feet

• Consider steel toed footwear if there is a chance of heavy items landing on feet

Liquid Dispensing Liquid Dispensing

• Remind yourself of the hazards • Always wear a full face shield, goggles, leather or cryogenic gloves, safety shoes, and aprons when transferring liquid. • Always have a co-worker present

• Ensure that the liquid cannot collect in pants • Two person lift of Dewars greater than 20 litre capacity cuffs or travel down into shoes. Do not tuck cuffs into pants! Cuff gloves over sleeves. • Ensure area/room is well ventilated • Transfer of liquids at pressures higher than • Avoid using a funnel 22 psig into open vessels such as small dewars can lead to excessive splashing. This could result in injury from freezing of the body part

11 Liquid Withdrawal Liquid Dispensing Operation • Ensure that withdrawal hose is equipped with a • Caution!!! phase separator to prevent splashing. Check with Before use, always confirm that the fittings are supervisor or appropriate for the product identified on the supplier cylinder label. If a mismatch appears, do not attempt to use the container. • Never dispense If help is needed, ask your supervisor or supplier liquid into an unapproved container, such as a Thermos ® bottle. It will shatter!

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A Liquid Helium

• Super cold at - 452 F (- 268 C)

OTHER CRYOGENIC FLUIDS • Special container needed for more insulation

• Personal Protective Equipment (PPE) extremely important

• Like Liquid Nitrogen, an inert gas

• Will not support life or combustion

• Asphyxiation potential same as Liquid Nitrogen

Liquid Oxygen Liquid Hydrogen

• Not as cold as liquid nitrogen • Super cold at - 423 F (- 253 C)

• Incompatible with flammable, organic, and combustible • Hydrogen gas is explosive materials • Do not use near open flames or other sources of • Avoid contact with heat, sparks, and flame. ignition. • Asphyxiation potential same as Liquid Nitrogen • NO SMOKING OR OPEN FLAMES signs should be posted in areas that use liquid oxygen • Second Highest Expansion Rate of the Liquid gasses (850) • Highest volume expansion rate of the Liquid gasses (860)

12 T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A Liquid Argon

• Like Liquid Oxygen, an inert gas TROUBLESHOOTING • Will not support life or combustion

• Asphyxiation potential same as Liquid Nitrogen

Trouble Shooting Trouble Shooting

• Issue: Container top covered with frost • Issue: Gas vents intermittently through safety relief valve

• Possible Cause: High product use • Possible cause: Probably normal operation. Gas generated due to heat leak into cylinder causes head pressure to build • Recommended Response : Normal operation

• Recommended Response: Ensure inactive containers are stored in well ventilated area. Rotate inventory

Trouble Shooting Trouble Shooting

• Issue: Gas vents continuously through safety valve • Issue: Gas vents during use through safety relief valve

• Possible Cause: Possible relief valve failure or excessive • Possible Cause: Set point on regulators exceeds safety heat leak relief valve setting

• Recommended Response : Remove container or • Recommended Response : Reduce set point on vent the exhaust to a well ventilated area. Relieve product through pressure building regulator-Contact supervisor or supplier for vent valve. Check to see if safety relief valve is frozen open. assistance Contact supervisor or supplier for assistance

13 Trouble Shooting Trouble Shooting

• Issue: Pressure in the container is low • Issue: Pressure in the container is low

• Possible Cause: Leak from container • Possible Cause: Pressure building valve is not fully opened • Recommended Response : Use appropriate leak detection fluid to check for leaks in connections. Examine container • Recommended Activity: Open valve fully for signs of frost. If leaks are on container itself, contact supervisor or supplier

Trouble Shooting Trouble Shooting

• Issue: Pressure in the container is low • Issue: Pressure in the container is low

• Possible Cause: Pressure building regulator not set high • Possible Cause: Pressure building valve is open enough • Recommended Response : Close the valve if frost • Recommended Response : Adjust to increase is visible on the pressure building vaporizer near the bottom of the pressure-contact supervisor or supplier tank-contact supervisor or supplier

Trouble Shooting Trouble Shooting

• Issue: Pressure in the container is too high • Issue: Pressure in the container is too high

• Possible Cause: Leaking or improper setting of pressure • Possible Cause: Vacuum integrity failing building regulator • Recommended Response : If container walls are • Recommended Response : Reduce regulator covered with frost, contact supervisor or supplier setting to achieve desired pressure level-contact supervisor or supplier

14 Trouble Shooting Trouble Shooting

• Issue: Container has isolated spots of frost • Issue: Container surface is uniformly covered with frost

• Possible Cause: Container may have been damaged, • Possible Cause: Vacuum integrity compromised compromising integrity of insulation • Recommended Response: If accompanied by a • Recommended Response : Contact supervisor or high rate of product venting through the safety relief valve, or high call supplier for replacement rate of pressure increase, call supplier

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A Resources Conclusion

• Chemical Safety Manual: http://riskmanagement.ok.ubc.ca/safety/chemsafety/lab- • Please complete the short quiz. safety-guidebook.html

• Canadian Center for Occupational Health Think Safety… and Safety: https://www.ccohs.ca/oshanswers/prevention/cryogens.html

• Risk Management Services www.riskmanagement.ok.ubc.ca

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A

15