Standard Operating Procedure (SOP) - McMaster Department of ...

Standard Operating Procedure (SOP)
For using Cryogenics (Liquid Nitrogen)
#1 General Process Description
Liquid nitrogen is used for many different applications in the department of Materials
Science and Engineering. Liquid Nitrogen used for undergraduate labs (quenching,
thermodynamics, heat capacity of metals, and cooling Charpys for Ductile to Brittle
Transition). Liquid Nitrogen is also used for instrumentations (Glow Discharge Optical
Emission Spectrometry and Inductively Coupled Plasma) which uses the gas produced
from the boiling of the Liquid nitrogen in a high pressure liquid nitrogen dewar. All
work described in this SOP will be conducted in rooms JHE 134, 240, 244, 245, or 247.
You MUST have WHMIS training prior to working in the lab. Contact Person is Ed
McCaffery Laboratory Manager (Room JHE 248 ext 24985).
#2 Hazards of Liquid Nitrogen/ Class of Hazard
Although nitrogen is nontoxic and inert, it can act as a simple asphyxiant by displacing
the oxygen in air to levels below that required to support life. Inhalation of nitrogen in
excessive amounts can cause dizziness, nausea, vomiting, loss of consciousness, and
death. Death may result from errors in judgment, confusion, or loss of consciousness that
prevents self-rescue. At low oxygen concentrations, unconsciousness and death may
occur in seconds and without warning. Personnel, including rescue workers, should not
enter areas where the oxygen concentration is below 19.5%, unless provided with a selfcontained
breathing apparatus or air-line respirator. Liquid nitrogen temperature is
(-196°C), and at this temperature cause severe tissue damage if skin comes in contact
with the liquid.
#3 Personal Protective Equipment (PPE)
One must be thoroughly familiar with the properties and safety considerations before
handling a cryogenic liquid and its associated equipment. The eyes are the most sensitive
body part to the extreme cold of the liquid and vapors of cryogenic liquids. The
recommended personal protective equipment for handling cryogens are:
1. Full Face Shield over safety glasses,
2. Loose-fitting thermal insulated or leather gloves
3. Long sleeve shirts, and trousers without cuffs.
4. In addition, safety shoes are recommended for people involved in the handling of
containers. Depending on the application, special clothing suitable for that application
may be advisable. NO Sandals or Open Toed Shoes!

SOP – Liquid Nitrogen.
A special note on insulated gloves: Gloves should be loose-fitting so they are able to
be quickly removed if cryogenic liquid is spilled on them. Insulated gloves are not
made to permit the hands to be put into a cryogenic liquid. They will only provide
short-term protection from accidental contact with the liquid. In emergency situations,
self-contained breathing apparatus (SCBA) may be required.
#4 Engineering / Ventilation Controls
Store and use this product with adequate ventilation. Do not store in a confined space.
Cryogenic containers are equipped with pressure relief devices to control internal
pressure
#5 Special Handling Procedures and Storage Requirements
Under normal conditions, these containers will periodically vent product. Do not plug,
remove, or tamper with any pressure relief device. Never allow any unprotected part of
the body to come in contact with uninsulated pipes or equipment that contains cryogenic
product. The extremely cold metal will cause the flesh to stick fast and tear when one
attempts to withdraw from it. Use a suitable hand truck for container movement.
Containers should be handled and stored in an upright position. Do not drop, tip, or roll
containers on their sides. Do not remove or interchange connections. Contact the vendor
if you experience any difficulty operating the container valve or with the container
connections. Discontinue use. Use the proper connection. DO NOT USE ADAPTERS!
Use piping and equipment designed to withstand the pressures to be encountered. On gas
withdrawal systems, use a check valve or other protective apparatus in any line or piping
from the container to prevent reverse flow. To prevent cryogenic liquids or cold gas from
being trapped in piping between valves, the piping should be equipped with pressure
relief devices. Only transfer lines designed for use with cryogenic liquids should be used.
Some elastomers and metals such as carbon steel may become brittle at low temperatures
and will easily fracture. These materials must be avoided in cryogenic service. It is
recommended that all vents be piped to the exterior of the building or to a well ventilated
indoor space.

SOP – Liquid Nitrogen.
#6 Accident Procedures
People suffering from lack of oxygen should be moved to fresh air. If the victim is not
breathing, administer artificial respiration have someone call 88. If breathing is difficult,
administer oxygen. Obtain immediate medical attention. Self-contained breathing
apparatus (SCBA) may be required to prevent asphyxiation of rescue personnel.
For skin contact with cryogenic liquid nitrogen, remove any clothing that may restrict
circulation to the frozen area. Do not rub frozen parts, as tissue damage may result. As
soon as practical, place the affected area in a warm water bath that has a temperature not
in excess of 105°F (40°C). Never use dry heat. Call a physician as soon as possible.
Frozen tissue is painless and appears waxy with a possible yellow color. It will become
swollen, painful, and prone to infection when thawed. If the frozen part of the body has
been thawed, cover the area with a dry sterile dressing with a large bulky protective
covering, pending medical care. In the case of massive exposure, remove clothing while
showering the victim with warm water. Call a physician immediately.
If the eyes are exposed to the extreme cold of the liquid nitrogen or its vapors,
immediately warm the frostbite area with warm water not exceeding 105°F (40°C) and
seek immediate medical attention.
Contact Emergency Response (88), then and Lisa Morine Ext 23314 and Ed McCaffery
Ext 24895.
#7 Waste Disposal
Not Applicable
#8 Training requirements
Prior to entering and working in the laboratory, you must have completed the EOHSS
WHMIS training. You will have to retain training documentation for at least one year.
Any person conducting work using this SOP must receive training on the contents of this
SOP.
#9 Approval Required
All research staff must be trained prior to starting work with the cryogenics. Under no
circumstances it is allowed to work with the liquid nitrogen, while being alone in the
laboratory. Always ask a second person to be in the lab with you. If you have to work
with liquid nitrogen and you are alone, you have to ask for approval from your
Supervisor then Laboratory Manager Ed McCaffery.
#10 Decontamination
N/A.

SOP – Liquid Nitrogen.
#11 Designated Area
Upon leaving a designated work area, remove any personal protective equipment worn
and wash hands. After each use (or day), wipe down the immediate work area. At the end
of each project, thoroughly decontaminate the designated area before resuming normal
laboratory work in the area.
#12 Precise Process Description
Always handle cryogenic liquids carefully. Their extremely low temperatures can
produce cryogenic burns of the skin and freeze underlying tissue. When spilled on
a surface, they tend to spread as far as the quantity of liquid spilled and the
physical confines of the area permit. They can cool large areas. The vapors
coming from these liquids are also extremely cold and can produce burns.
Exposure to these cold gases, which is too brief to affect the skin of the face or
hands, may affect delicate tissues, such as the eyes. Stand clear of boiling and
splashing liquid and the cold vapors that are released. Boiling and splashing
always occur when filling a warm container or when inserting objects into the
liquid. Always perform these operations slowly to minimize the splashing and
boiling. Never allow any unprotected part of your body to touch uninsulated pipes
or vessels containing cryogenic liquids. The extremely cold material may stick
fast to skin and tear the flesh when you attempt to withdraw it. Even nonmetallic
materials are dangerous to touch at these low temperatures. Use tongs to immerse
and remove objects from cryogenic liquids. In addition to the hazards of frostbite
or flesh sticking to cold materials, objects that are soft and pliable at room
temperature, such as rubber or plastics, are easily broken because they turn brittle
at low temperatures and may break when stressed.

SOP – Liquid Nitrogen.
Laboratory Spill Response Procedures
Health Threatening Situation - In the event of an imminent or actual health-threatening
emergency (threatening local or public health, safety, or welfare; or the environment
outside the immediate area):
1) CALL 88 FOR THE EMERGENCY RESPONSE
REMAIN IN THE AREA TO ADVISE RESPONDERS.
2) ACTIVATE LOCAL ALARM SYSTEMS
3) Once personal safety is established, call EOHSS at Ext 24352 and proceed with
local notifications, below.
Non-Health Threatening Situation – In the event of a major burn or asphyxiation:
1) Notify McMaster Responders: Call 88 (24 hours/day, 7 days/week), then
2) Provide local notifications:
Name Phone Number Title
Ed McCaffery Ext 24895 Lab Manager/ Principal Investigator
Lisa Morine Ext 23314 EOHSS
Local Response Situation – In the event of a minor burn:
1) Notify personnel in the area and restrict access.
Disclaimer: The SOP as written contains our best understanding at this time on how to
work safely with this piece of equipment. When new information is found that would
improve the safe use of this equipment it will be added in a timely manner. As it stands
we cannot be held liable for misuse or abuse of these instructions through negligence on
the user’s part or based on the content of these notes.