The University Safety Manual gives an overview of Flammable Liquids in Laboratories And Chemical Storage Rooms, Chemical Laboratories, Radiation Producing Equipment and Materials, Biological Laboratories, and Shipping Hazardous Waste.
The Department of Biological Sciences has a Chemical Hygiene Plan. Below are outlined the lab postings and handling of liquid nitrogen.
Users should also review MIOSHA resources and the campus Emergency Guide.
10.1 POSTINGS
See the Emergency Response Poster for required postings outside of all lab spaces.
It is recommended that the following be posted inside the lab door:
- location of Standard Operating Procedures (SOPs)
- location of spill clean up equipment
- location of ladders (if there is not one in the lab)
- additional personnel contact information not listed outside the laboratory.
Facility users must have emergency shutdown procedures and emergency contact numbers posted next to unattended experimental apparatuses or on the lab door.
Food items that might be tested or used in experiments must clearly be labeled “not for human consumption.”
10.2 Labeling chemicals and laboratory samples
There are specific federal and state regulations and Institutional rules on labeling chemicals, chemical solutions, and laboratory samples. One guiding concept is that the contents of any container and the hazards associated with those contents must be readily apparent.
10.2.1 Chemicals in the original manufacturer's bottle or container
Chemicals or pre-mixed chemical solutions that are purchased must have a label that meets the requirements of the Globally Harmonized System as outlined by OSHA and MIOSHA. The specifics can be found on the OSHA website, but briefly the label has six required elements:
- A product identifier.
- One or more pictograms.
- One or more signal words.
- One or more hazard statements.
- One or more precautionary statements.
- The supplier contact information.
These required items must be not be removed, covered up, or modified as long as original contents are still in the container.
10.2.2 Chemicals and solutions in secondary containers
All secondary containers of chemicals and solutions must be labeled. The label must include the name of the chemical or solution and information about the hazards (if any) associated with the chemical/solution. The hazards can be either descriptive words or
. The label must be in English, legible, and understandable to non-chemists. Abbreviations or chemical formulas are generally not acceptable unless they are in common usage by a non-scientist.
There is one narrow exception to this rule. While not considered good lab practice and generally discouraged, it is legal to transfer a chemical into an unlabeled container if, and only if, that container will always be in possession of the person that originally transferred it and if its contents is used up by the end of their work shift. Note that leaving the container unattended, even briefly, violates the spirit of this exception and possibly the law.
Note that ALL containers need to be labeled, even those that hold non-hazardous substances such as water. Also note that in addition to laboratory glassware, all items holding chemicals solutions need to be labeled, including spray bottles, squirt bottles and carboys.
The following examples are intended to emphasize correct labeling:
| Unacceptable | Acceptable |
|---|---|
| DI H2O | Deionized Water or Deionized H2O |
| 6N HCl | 6N Hydrochloric Acid, Corrosive (alternately you could use the “corrosive” pictogram) |
| EtOH | Ethanol, Flammable (or the flammable pictogram) |
10.2.3 Labeling of samples
Samples being actively processed and those in storage need to meet the labeling requirements outlined in 10.2 Labeling chemicals and laboratory samples. If the sample containers are small, or if there are multiple bottles of the same hazard, it is acceptable to label the container, box, cabinet or shelf with a generic hazard posting. Alternately, if the samples are coded, it is acceptable to post the location of the master code notebook that lists the hazards.
For example:
A researcher has a refrigerator full of lake water samples. Instead of labeling each individual bottle, the refrigerator could be labeled “all containers in this refrigerator contain lake water unless otherwise labeled.”
A researcher has a box of small vials with samples waiting for analysis. Instead of labeling each individual vial, the box could be labeled “See log book (then provide the location of the log book) for individual sample hazards.”
10.3 Procedures for specific chemicals
10.3.1 Liquid Nitrogen Safety and Handling
Liquid Nitrogen Properties
See Liquid Nitrogen SDS for more information.
Appearance: colorless cryogenic liquid
Odor: odorless
Boiling Point (1 atm): -195.8°C
Melting Point: -209°C
Specific Gravity: 0.967 (air=1)
Expansion Ratio (liquid to gas): 1 to 696.5
Required Personal Protection Equipment and Precautions
- Safety glasses
- Face shield
- Low temperature gloves
- Closed toe shoes
- Pants
- No metal jewelry/watches on the hands or wrists
General Precautions
- Liquid nitrogen can cause severe burns (due to frostbite) even with brief exposure. Cryogenic gloves, safety goggles, a face shield, and closed toed shoes and pants must be worn when dispensing and handling liquid nitrogen. A full length apron or lab coat is also recommended to minimize the chance of a spill going into your shoes.
- Do not wear metal jewelry or watches on hands or wrists when handling liquid nitrogen. These items may freeze to your body.
- Guard against pressure build-up by using a pressure relief vessel or a venting lid.
- Liquid nitrogen will condense oxygen from the air. An example of this happening is if a person leaves their vacuum pump’s coldfinger in a Dewar of liquid nitrogen overnight. In the morning the coldfinger will contain liquid oxygen up to the level of the nitrogen in the Dewar.
- Asphyxiation—if sufficient liquid nitrogen is vaporized and reduces atmospheric oxygen below 19.5% (normal is around 21%) you are at risk of oxygen deprivation. Rapid venting can cause near-total displacement of normal air, vent slowly in a well ventilated area.
- Do not carry liquid nitrogen in a passenger elevator.
- Only use vessels designed for extreme cold. Not all Dewars are rated for liquid nitrogen.
- Cryotubes containing samples stored under liquid nitrogen may explode without warning. Liquid nitrogen may enter the tube through small cracks, when the tube thaws the liquid nitrogen may rapidly expand causing the tube to burst.
- Lower the Dewar buckets slowly into the liquid nitrogen to prevent boiling and splashing
Dispensing
- To fill, lower the phase separator attached to the end of the transfer hose into the vessel being filled. Slowly open the valve on the dispensing tank until liquid nitrogen begins to flow. Fill tank to desired level. Note: level should remain below the level of stored cryotubes, they should be stored in the vapor phase.
- The phase separator separates gas from liquid allowing only liquid nitrogen to fall into the Dewar.
- Do not leave tank unattended while filling.
- Deliver directly to the tank being filled; do not allow the liquid nitrogen to fall a distance to reach the receiving vessel.
- Do not hold the vessel with unprotected hands during filling
First Aid
EMERGENCY CONTACT 911
Inhalation
If persons are suffering from lack of oxygen, they should be moved to fresh air. If the victim is not breathing, artificial respiration should be administered.
Skin Contact
Remove clothing that may restrict circulation to the frozen area. Do not rub frozen tissue, it may cause tissue damage. Warm affected area in a water bath (do not exceed 105°F), do not use dry heat. Contact a physician as soon as possible.
Frozen tissue is painless and appears waxy with a possible yellow color. When thawed, it will become swollen, painful, and prone to infection. Once the frozen area becomes thawed, cover the area with dry sterile dressing and a protective covering pending medical care.
Eye Contact
Immediately warm frostbite area with warm water and seek medical attention.
References
https://www.chem.purdue.edu/chemsafety/chem/liquid-nitrogen.php
www.ehrs.upenn.edu/media_files/docs/pdf/cryogen.pdf
NI 180LT22 = 180L Liquid nitrogen at 22PSI
MVE 9713159 = 4ft Transfer hose
MVE 10615869 = Phase separator