OHS026
Safe Work Procedure
Faculty/Division
Medicine
Document number
SOMS_IIR_SWP11
School/ Divisional Unit
School of Medical Sciences
Initial Issue date
26.6.09
Current version
1.2
Current Version
Issue date
18.02.2010
Next review date
18.02.2011
The Writing Safe Work Procedures Guideline (OHS027) should be consulted to assist in the completion of this
form.
Safe Work Procedure Title and basic description
Title: Liquid Nitrogen Dewars and General Liquid Nitrogen Safety
Description: Using liquid nitrogen tanks for storage of biological samples and transporting liquid nitrogen to the laboratory.
Associated risk assessment title and location: RISK ASSESSMENT: 11_RA_Handling Liquid Nitrogen_MD
Describe the activity or process
Background
Liquid nitrogen is a cryogenic liquid used to snap freeze various cell/tissue/fluid samples for long term storage and preservation.
There are many safety issues associated with the use of liquid nitrogen as it has the ability to freeze living tissue and can also cause
asphyxiation (suffocation) and must be used with extreme safety.
Liquid nitrogen dewars (containing samples) are stored within a designated room on the lower ground floor room 9 (LG9) and room
8 (LG8) Wallace Wurth (accessible by the goods lift or Stairs in the Wallace Wurth building). The liquid nitrogen room is equipped
with an exhaust fan and oxygen level detector for your safety (see ‘suffocation danger’ for details).
Handling of liquid nitrogen dewars
Before entering the liquid nitrogen facility, check the oxygen detector (on left side of door) to ensure that the oxygen level is within a
safe range within the facility (18-21). Also check that the fan exhaust set to High (also on left side of door). Also check the ventilation
fans are working (there are streamers connected to the vents – check that there is air movement) If either the yellow or red alarms
(above the door are lit) do not enter room and notify the room custodian (Liz Keoshkerian x52494).
1.
2.
Check liquid nitrogen folder for location of vial or available spaces before opening liquid nitrogen dewar.
If no alarms are detected and oxygen levels are safe, it is safe to enter the facility. Keep doorway partly or completely open
whilst inside the facility to avoid suffocation.
3. Appropriate personal protective equipment (gloves, face shield and long sleeve lab coat) is provided within the facility and
must be worn prior to opening liquid nitrogen dewar.
4. Remove dewar lids.
5. Samples are stored within cryovials in boxes which are secured within racks in the dewar.
6. To store new samples, lift rack from dewar carefully and wait for remaining liquid nitrogen to drain out of boxes. Remove
the rack from dewar and use the step ladder provided to aid with this.
7. Place rack upon a large Styrofoam lid or in the metal tray to avoid damage to the floor. Wait a couple of seconds for any
remaining liquid nitrogen to evaporate.
8. Remove the metal bar securing the boxes and place new cryovials into appropriate box. ALWAYS KEEP FACE SHIELD
ON AS CRYOVIALS CAN EXPLODE WHEN REMOVED FROM LIQUID NITROGEN IF ANY AIR LEAKS INTO VIALS.
9. Replace metal bar and place rack back into the dewar slowly to avoid any liquid nitrogen splashing.
10. Close dewar. Lids. Remove PPE and close door (door automatically locks).
List all resources required including plant,
chemicals, personal protective clothing and
equipment, etc
Personal Protective Equipment (PPE)
• Wear clean and dry clothing that covers arms and legs.
• The clothing should be loose, so it is easy to remove it if an accident happens.
• Avoid wearing open trouser pockets and wrapped sleeves.
• Wear cryogenic gloves (provided) under the sleeves so no liquid can fall in the gloves.
• Wear safety glasses and the face shield provided to ensure complete protection of the face and neck.
• Wear non-slip closed footwear and a lab coat which has long sleeves (provided).
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Safe Work Procedure
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Date Effective: 01/01/2007
Current Version: 1.2, 15/08/2007
List potential hazards and risk controls including
specific precautions required
Suffocation danger
• Make sure there is enough ventilation in the facility as liquid nitrogen immediately turns into a gas when exposed to room
temperature and pressure. This displaces oxygen from the air resulting in low oxygen levels-asphyxiation risk. Keep door of the
facility open when inside.
• Avoid transporting liquid nitrogen in lifts carrying other persons – use the goods lift or the stairs .
• Carbon dioxide in air is a potential danger. Concentrations from 2.5% cause breathing problems and a concentration of 20% is
deadly within some seconds (also when there is still enough oxygen available)
Damage to surfaces and footwear
· Liquid nitrogen makes stone floors, normal shoe soles and plastic materials crisp and crumbles easily, so take care! (use the step
ladder if necessary and the Styrofoam lid or metal tray)
· Normal thermos flasks cannot handle low temperatures and the danger of explosion is present.
A. DISPENSING LIQUID NITROGEN FROM STORAGE TANKS
1. Dispense only into Dewars that are rated for liquid nitrogen.
a. Never use a Dewar that does not have a pressure relief valve or pressure venting lid/stopper.
b. Never use Dewars with makeshift or homemade lids/stoppers.
c. Use pressure venting lids/stoppers supplied by the Dewar manufacturer
2. Dispense only into Dewars that are:
a. Equipped with carrying handles or wheels
b. Stable/not in danger of tipping over easily
3. Persons filling Dewar(s) will be in constant attendance during filling
4. Prevent Splashing. Place filling hose at or below the mouth of the receiving Dewar
5. Wear Required Personal Protective Equipment
a. Cryogenic Gloves
b. Lab Coat with sleeves pulled over cuffs of Cryogenic Gloves
c. Liquid proof Shoe Covers/Spats
d. Chemical Splash Goggles or Laboratory Face Shield
B. TRANSPORTING LIQUID NITROGEN WITHIN LABORATORIES AND BETWEEN LABORATORIES IN THE SAME BUILDING
1. Use Dewars rated for liquid nitrogen (see A.1 above).
2. Do not transport Liquid Nitrogen in Open Containers
3. Wear Required Personal Protective Equipment (see A.5 above)
4. If you are carrying a Dewar containing Liquid Nitrogen:
a. Make sure Dewar is your ONLY load (no books, coffee, other items)
b. Carry transport Dewar as far away from your face and body as possible
c. Watch for other people who may run into or bump you
List emergency shutdown instructions
If possible, put the lid on the dewar and vacate the room.
Contact the Plant Custodian (Susan Yang x58274) and the Room Custodian (Liz Keoshkerian x52494)
For major emergencies dial x56666
List clean up and waste disposal requirements
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If liquid nitrogen is spilt inside a building make sure there is adequate ventilation to avoid suffocation.
If spill occurs outside, keep up wind of the spill.
Evacuate the area until the liquid has evaporated and oxygen levels are at normal atmospheric levels.
A claw can be used to retrieve samples/tubes. In this case, please contact Merideth Hatton (xn 52536).
If there is a large spill, or if a vessel is leaking, contact emergency services (UNSW Emergency, xn 56666) and notify the
supplier.
List legislation, standards and codes of practice used
in the development of the SWP
NSW OHS Act 2000
NSW OHS Regulation 2001
Australian Standard AS 1894 Code of Practice for the Safe Handling of Cryogenic Fluids
Australian Standard AS 2243.2 Safety in Laboratories: Chemical Aspects
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Safe Work Procedure
Uncontrolled document when printed
Date Effective: 01/01/2007
Current Version: 1.2, 15/08/2007
Supervisory approval, training, and review
Supervisor:
Signature:
Plant custodian: Susan Yang (x58274)
Signature
List competency required – qualifications, certificates, licensing, training - eg course or instruction:

UNSW Laboratory Safety Awareness training

UNSW Occupational Health & Safety Awareness training

UNSW Hazardous Substances training
Hands-on training in use of the equipment by an authorized user
SWP review date: 18.02.2010
Responsibility for SWP review: Susan Yang
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Page 3 of 3
Safe Work Procedure
Uncontrolled document when printed
Date Effective: 01/01/2007
Current Version: 1.2, 15/08/2007