Liquid Nitrogen in a Dewar: Everything You Need to Know
Liquid nitrogen is a crucial element in scientific research, medical and industrial applications. It is a colorless and odorless liquid that has a boiling point of -196 degrees Celsius. Due to its extremely low temperature, it is often stored in containers called dewars to maintain its liquid state. But how much liquid nitrogen can a dewar hold?
What is a Dewar?
A dewar is a type of container that is used to store liquids at very low temperatures, such as liquid nitrogen. It is named after its inventor, James Dewar, a Scottish chemist and physicist who created the first vacuum flask in 1892. A dewar is made up of an inner and outer shell that is separated by a vacuum. The vacuum helps to minimize heat transfer and keep the liquid inside the dewar in a liquid state.
How Much Liquid Nitrogen Can a Dewar Hold?
The amount of liquid nitrogen that a dewar can hold depends on several factors, such as the size and type of dewar, the amount of insulation, and the ambient temperature. Generally, dewars come in various sizes, ranging from small handheld dewars to large cryogenic storage tanks.
Small handheld dewars, also known as cryogenic storage containers, can hold between 0.5 to 2 liters of liquid nitrogen. These types of dewars are commonly used in laboratories and medical facilities for the storage of biological specimens, such as blood samples and tissue cultures.
Medium-sized dewars, which are typically used for transporting and storing liquid nitrogen, can hold between 20 to 50 liters of liquid nitrogen. These dewars are often used in industrial applications, such as cryogenic freezing of food products and transportation of liquid nitrogen to welding sites.
Large cryogenic storage tanks, which are used for the long-term storage of liquid nitrogen, can hold up to several thousand liters of liquid nitrogen. These tanks are typically used in industries such as pharmaceuticals, semiconductors, and aerospace for the storage of raw materials and finished products.
Factors that Affect the Amount of Liquid Nitrogen a Dewar Can Hold
- Dewar Size and Type
As previously mentioned, the size and type of dewar affect the amount of liquid nitrogen it can hold. Small handheld dewars can hold less liquid nitrogen than medium-sized dewars or large cryogenic storage tanks.
- Amount of Insulation
The amount of insulation in a dewar affects how well it can retain the liquid nitrogen. Dewars with thicker insulation can hold more liquid nitrogen than dewars with thinner insulation.
- Ambient Temperature
The ambient temperature also affects the amount of liquid nitrogen a dewar can hold. When the temperature is warmer, the liquid nitrogen will start to evaporate, reducing the amount of liquid nitrogen in the dewar.
- Liquid Nitrogen Usage
The rate at which the liquid nitrogen is being used also affects the amount of liquid nitrogen in the dewar. If the liquid nitrogen is being used at a high rate, the dewar will run out of liquid nitrogen faster than if it were being used at a slower rate.
In conclusion, the amount of liquid nitrogen that a dewar can hold varies depending on several factors such as the size and type of dewar, the amount of insulation, and the ambient temperature.