REFRIGERATED AND CRYOGENIC LIQUID
SAFETY RESOURCE CENTER
Understanding Refrigerated and Cryogenic Liquid Hazards
Refrigerated and cryogenic liquids are gases that have become a liquid due to very low temperatures. These liquids are extremely cold; cryogenic liquids are defined as having a boiling point below –130 °F (–90 °C). Once liquefied, all refrigerated and cryogenic liquids must stay extremely cold or they will return to a gas state in a process known as vaporization.
Anyone who handles refrigerated or cryogenic liquids should be aware of their unique properties and potential hazards. In addition to being extremely cold, other hazards include high rates of vaporization, rapid expansion, and fogging. This safety poster, provided by the Compressed Gas Association, provides basic safety information for the safe use of refrigerated and cryogenic liquids.
The specific gas product being used can pose other hazards in addition to being a refrigerated or cryogenic liquid. The container label and safety data sheet (SDS) provide detailed hazard information and handling precautions. You should always read and understand the label and the SDS before using any product and should also follow the instructions and safety precautions provided by your product supplier.
Refrigerated & Cryogenic Liquid Safety Reminders
Wear all appropriate personal protective equipment (PPE).
Read and understand the specific hazards of the gas product in use.
Never consume or directly touch refrigerated or cryogenic liquids.
Only use containers and equipment designed for refrigerated or cryogenic liquids.
Never place refrigerated or cryogenic liquids in sealed, non-vented containers.
Follow local requirements for ventilation and monitoring.
Solvent Direct offers safety posters as educational resources to support the safe use of our industry’s products and equipment. It is important to note that these posters are not a substitute for reading and following codes and regulations, industry standards, and supplier instructions. Purchase your refrigerated and cryogenic liquid safety poster today or the full set.
REFRIGERATED AND CRYOGENIC LIQUID
Refrigerated and cryogenic liquids are gases that change to a liquid once they drop below a certain temperature, known as the boiling point, which is different for each product. Cryogenic liquids are defined as having a boiling point below –130 °F (–90 °C). For example, the boiling point for water is 212 °F (100 °C). Above this temperature, water vaporizes into a gas (steam). Between the boiling point and 32 °F (0 °C), water is a liquid. Likewise, refrigerated and cryogenic liquids turn into gas above their boiling points, and are liquids at temperatures below their boiling points. Once liquefied, all refrigerated and cryogenic liquids must stay extremely cold or they will return to a gas state in a process known as vaporization.
All refrigerated and cryogenic liquids have several common properties:
high rates of vaporization;
rapid expansion; and
In addition to the characteristics shared by all refrigerated and cryogenic liquids, each product has its own unique hazards that should be understood and managed through safe handling practices. Examples of other hazards that can be present include:
asphyxiation from inert products such as helium, nitrogen, and argon, which can displace the oxygen needed to sustain life;
fires that can result from releases of flammable products, like hydrogen, or burn more vigorously due to release of oxygen or other oxidizing gases;
toxicity from products such as carbon monoxide, which can have adverse and sometimes permanent effects on your health; and
reactivity of the product with other chemicals or materials, for example oxygen reacting with organic materials such as oil, grease, asphalt, or dirt.
To find the specific hazards are presented by the product that you are working with, you must read and understand the safety data sheet (SDS) and product label.
Refrigerated and cryogenic liquids, cold gas vapors, or the cold exterior of a vessel or piping holding a refrigerated or cryogenic liquid can freeze human tissue on contact. Delicate tissue, such as the eyes, can be damaged by the exposure to cold gases even when the contact is too brief to damage the skin. Touching an uninsulated surface can cause your skin to stick to the material, resulting in skin tears when you try to pull away. Breathing cold vapors can damage your lungs. Direct contact with refrigerated or cryogenic liquids, cold gas vapors, or uninsulated pipes or vessels containing refrigerated or cryogenic liquids should be avoided. Use of appropriate personal protective equipment, also referred to as PPE, is an important way to protect yourself from the cold associated with refrigerated and cryogenic liquids.
Refrigerated and cryogenic liquids and their cold gas vapors can cause common materials like steel, rubber, and plastics to become brittle and break. This can be particularly dangerous in the case of a spill or unexpected exposure, where materials not designed for refrigerated or cryogenic service can rupture or crack.
Small quantities of refrigerated or cryogenic liquid will convert to very large quantities of gas as they vaporize. For example, liquid nitrogen expands at a ratio of 700 to 1, meaning one unit of liquid nitrogen will produce 700 units of gaseous nitrogen. If the vaporized gas is trapped in a sealed container, it will produce very high pressures. Any vaporization that occurs when product is trapped in piping between valves or within equipment without appropriate pressure relief can lead to a violent rupture potentially causing an uncontrolled product release, injury to personnel, or damage to property and equipment. For this reason, pressurized refrigerated and cryogenic containers are protected by pressure relief devices that relieve pressure from the container or piping by venting excess vapor. Non-pressurized liquid containers are equipped with loose-fitting caps that can come off to allow excess pressure to escape. Never block or tamper with any pressure relief devices.
A refrigerated or cryogenic liquid container that has cold spots or frost on the outside, is venting continually, or shows a rapid pressure rise on the tank pressure gauge is showing signs of loss of vacuum. Also, plugs of ice or foreign material can form in the vents and openings of these containers or their piping, preventing proper pressure relief. The vessel can rupture if the proper action is not taken quickly. Prevent plugs by following the supplier’s operating procedures.
If you have a container that is showing signs of loss of vacuum or has formed an ice plug, follow your company’s procedures for handling these containers or contact your gas supplier for immediate assistance. Do not attempt to remove the plug without consulting the supplier. If possible, remove the vessel to a remote location in accordance with the supplier’s recommendations.
LEAKS AND SPILLS
Refrigerated or cryogenic liquid spills can create a wide range of hazards such as:injury to personnel;
embrittlement of surrounding structures, piping, and equipment; and
The cold from refrigerated or cryogenic liquids and their cold gas vapors can condense the moisture in air, creating a fog that can limit visibility. The fog will disappear as the gas warms up to ambient temperature. It is important to remember that high concentrations of the product can be present without a visible cloud, or can extend past the area where the fog cloud is visible.Some products are cold enough to freeze the air around them. This can create an oxygen-enriched atmosphere in the area where the refrigerated or cryogenic liquid is present. In an oxygen-enriched atmosphere, materials that usually do not burn can catch fire, and fires will burn much more vigorously than normal.In the case of a major spill, shut off the source of the leak if possible and ventilate the area. Keep personnel out of the liquid pool and at a safe distance from the visible fog cloud. Establish the extent of the hazard zone by using atmospheric monitoring to determine where the air beyond the visible fog cloud is safe to breathe or work in. Only authorized personnel should be allowed near the spill site. No one should enter the spill area unless trained as a responder and properly equipped.Personnel exposed to the spill should leave the area immediately. If exposed to high concentrations of gaseous oxygen or flammable gases, you should avoid all sources of ignition (such as smoking) for at least 30 minutes until your clothing has been well ventilated. Clothing that becomes saturated with liquid oxygen or flammable products should be removed immediately and aired for at least 1 hour until it is completely free of liquid and gas vapors.
FIRST AID / EMERGENCY RESPONSE
If direct contact with a refrigerated or cryogenic liquid is made, a cold-contact burn (i.e., freezing of the skin or eye tissue) can result. Frozen tissue is painless and appears pale and waxy. As it begins to thaw, it becomes swollen, painful, and prone to infection. If there has been a massive exposure and the victim’s body temperature is low, it is critical to obtain immediate medical attention. If immediate medical attention is unavailable, rewarm the victim by immersing them in a warm water bath no hotter than 105 °F (40 °C). In all instances of a cold-contact burn, it is important to obtain medical assistance as soon as possible.
While waiting for medical assistance:
Move the victim to a warm room, if possible.
Remove any clothing not frozen to the skin that can restrict circulation to the frozen area.
DO NOT rub frozen areas, as tissue damage can result.
As soon as practicable place the affected area in a warm water bath that is no hotter than 105 °F (40 °C). Never use dry heat! Thawing can require from 15 – 60 minutes and should be continued until the affected skin turns pink or red.
If the frozen area thaws before medical attention is obtained, cover the area with a dry sterile dressing and a large, bulky protective covering.
Warm drinks and food may be offered to a conscious victim. Alcoholic beverages and smoking decrease blood flow to frozen tissue and should not be allowed.