Your Laboratory
Title/Subject
Author: Penny Stevens
Review History
Document Number:
Effective (or Post) Date:
Date of last review:
Reviewed by:
Fac12-01
26 February 09
3 Au 2010
Heidi Hanes
SMILE Comments: This document is provided as an example only. It must be revised to accurately reflect your lab’s
specific processes and/or specific protocol requirements. Users are directed to counter check facts when considering
their use in other applications. If you have any questions contact SMILE.
1. Purpose/Applicability
1.1.
Purpose - This Standard Operating Procedure establishes procedures for safe
handling of liquid Nitrogen in Cryogenic refrigerators and Dewar’s flasks.
1.2.
Scope – For all Laboratory personnel who will be handling liquid nitrogen.
1.3.
Two important properties of liquid Nitrogen that present potential hazards:
It is extremely cold. At atmospheric pressure, liquid Nitrogen boils
at –196oC.
Very small amounts of liquid vaporize into large amounts of gas.
One liter of liquid nitrogen becomes 0.7 m3 of gas.
2. Terms and Abbreviations
2.1.
2.2.
LN2 – Liquid Nitrogen
NCCLS – National Council of Clinical Laboratory Standards
3. Equipment and Reagents
3.1.
3.2.
3.3.
3.4.
3.5.
3.6.
List all equipment here.
Liquid nitrogen containers
Tools
Gloves
glasses
Room Monitoring alarm for low O2, etc.
4. Responsibilities
4.1.
4.2.
4.3.
Laboratory supervisor and all laboratory staff must ensure that this procedure
is implemented and utilized as written.
Laboratory supervisor will review this procedure annually.
Laboratory Director is responsible for any changes made to this SOP.
5. Procedures
5.1.
Specimen: N/A
Your Laboratory
5.2.
Warnings and Precautions
5.2.1.
The safety precautions in this SOP must be followed to avoid
potential injury or damage. Do not attempt to handle liquid nitrogen
until you read and fully understand the potential hazards, their
consequences, and the related safety precautions.
5.2.2.
Safety Recommendations – Buddy System
5.2.2.1. Notify another staff member before working with liquid
nitrogen or in a LN2 storage room.
5.2.2.2. Install an oxygen or LN2 room monitor and/or alarm. If
there is no monitor or alarm installed in LN2 rooms, staff should
work in pairs.
5.2.3.
Safety Recommendations – Containers
5.2.3.1. Use cryogenic containers that are specifically designed for
liquid nitrogen and made of materials that can withstand extreme
temperature differences. These containers should be filled slowly
to minimize internal stresses that occur when any material is
cooled.
5.2.3.2. Do not cover or plug any opening on liquid nitrogen
refrigerators or Dewar’s flask. Do not use any stopper or other
device that could interfere with the venting of gas.
5.2.3.3. Cryogenic liquid containers are designed to operate with
minimal or no internal pressure. Inadequate venting can result in
excessive pressure, which could damage or burst the container.
Use only the loose-fitting neck tube core supplied or one of the
approved accessories for closing the neck tube. Check the unit
periodically to be sure VENTING is not restricted by
accumulated ice or frost.
5.3. Quality Control
5.3.1.
5.3.2.
5.3.3.
LN2 Level and temperatures must be monitored and documented
daily.
Indicate the source, back-up source, and reliability of the LN2
supply.
List the minimum acceptable LN2 level to determine and initiate the
re-supply process.
Your Laboratory
5.3.4.
If the room is monitored for elevated nitrogen gas levels or oxygen
levels, indicate if monitors are checked and if documentation is
required.
5.4 Transfer Equipment
5.4.1.
Use a phase separator or special filling funnel to prevent
SPLASHING and SPILLING when transferring liquid nitrogen into
or from a Dewar flask or refrigerator. Use only small, easily handled
Dewar’s flasks for pouring liquid. For larger, heavier containers, use
a cryogenic liquid withdrawal device to transfer liquid from one
container to another. Be sure to follow all instructions supplied.
5.4.2.
Do Not Over Fill Containers.
5.4.3.
Filling above the bottom of the neck tube (or specified maximum
level) can result in OVERFLOW and SPILLAGE upon closing.
5.4.4.
Never Use Hollow Rods or Tubes as Dipsticks. When a warm tube
is inserted into liquid nitrogen, liquid will spout from the top of the
rod or tube. This can result in a risk of facial exposure due to
gasification and rapid expansion of the liquid inside the tube.
5.4.5.
Nitrogen Gas Can Cause Suffocation without Warning
5.4.5.1. Store and use only in a well ventilated area. As liquid
evaporates, nitrogen gas is released and displaces normal air.
This reduces the concentration of oxygen and can result in
asphyxiation.
5.4.5.2. Nitrogen gas is colorless, odorless and tasteless. It cannot
be detected by human senses and may be breathed as if it were
normal air. Breathing atmospheric air that contains less than 18%
oxygen causes dizziness and quickly results in unconsciousness
and death.
5.4.5.3. The cloudy vapor that appears when liquid nitrogen is
exposed to air is condensed moisture; not the gas itself. The
issuing liquid nitrogen gas is invisible.
5.4.5.4. Never dispose of liquid nitrogen in confined areas or places
that may expose others to the gas. Dispose only outside and in a
safe place. Pour the liquid slowly on gravel or bare earth where it
can evaporate without causing damage. Do not pour liquid on
pavement. Do not inhale the vapors.
Your Laboratory
5.6
5.7
Liquid Nitrogen Safety
5.6.1.
Protective Clothing – Always wear protective face covering,
insulated gloves and long sleeved clothing to help prevent
unnecessary exposure to liquid nitrogen.
5.6.2.
Contamination - If containers stored in liquid nitrogen contain
hazardous biological materials, they must be opened in appropriate
biological safety cabinets only and in accordance with (your lab’s)
safety policy for handling potentially infectious substances. Broken
containers within storage freezers pose a risk of contamination due
to potential survival of the released contents. Handle all broken
containers in accordance with (your lab) policy.
5.6.3.
Explosion - Liquid nitrogen is a cryogen with a boiling point of –
196C (- 320F). When removed from a liquid nitrogen atmosphere,
improperly sealed sample containers may explode. Placing
containers in vapor phase nitrogen for several hours before
immersing them in liquid nitrogen minimizes the risk of explosion.
First Aid
5.7.1.
If a person working with liquid nitrogen appears dizzy or loses
consciousness:
5.7.1.1.
5.7.1.2.
5.7.1.3.
5.7.1.4.
5.7.1.5.
5.7.2.
Move to a well-ventilated area immediately.
If breathing has stopped, apply artificial respiration.
If breathing is difficult, give oxygen
Call a physician.
Keep warm and at rest.
If exposed to liquid or cold gas:
5.7.2.1. Restore tissue to normal body temperature (37oC) as
rapidly as possible. Protect from further damage and infection.
5.7.2.2. Remove or loosen clothing that may constrict blood
circulation to the frozen area.
5.7.2.3. Call a physician.
5.7.2.4. Rapidly warm the affected part using water at (108oF) and
NEVER over (112oF)
5.7.2.5. Do not rub affected part either before or after re-warming.
5.7.2.6. The patient should neither SMOKE nor DRINK alcohol.
6. Appendices
6.1.
LN2 Monitoring and Maintenance Log
Your Laboratory
7. References
7.1.
Forma Scientific, Inc. P.O.Box 649 Marietta, Ohio 45750 USA.
TEL (740) 373-4763 Telefax (740) 373-4189. Manual No.
7007400