Dewar Flask
  • Dewar Flask

Dewar Flask


Main Features

  • Double-Walled Construction
  • Limited Contact Points
  • Cryogenic Storage Capability
  • Vacuum Sealing
  • Versatile Designs
  • Effective Thermal Insulation
  • Gas Management
  • Silver Coating

Description and Specification of Dewar Flask

What is Dewar Flask?

A Dewar Flask serves as a glass vessel explicitly designed to preserve the temperature of stored liquids. It does so by reducing the heat transfer to the surrounding air. It establishes a robust vacuum by employing a double-wall structure to reduce convection and conduction heat transfer. It also features silver-coated inner walls to impede heat radiation and diminish contact points between walls. All these result in exceptional thermal insulation. The cryogenic storage dewar, typically named Dewar flask, is often employed for safely storing materials with shallow boiling points, such as liquid nitrogen or helium. It is named after its inventor, James Dewar. It is usually applied in low-temperature physics and chemistry scenarios. It is present in varied shapes and sizes. The shapes include open buckets, flasks with loosely fitted stoppers, and self-pressurising tanks.

Some loss of cryogenic liquid is unavoidable over time, even if the flask is provided with excellent insulation properties. Therefore, checking the integrity of the vacuum insulation and refilling is essential to maintain the desired low temperature. A regular inspection is needed to preserve the effectiveness of the Dewar flask. All dewar share a common feature in their multi-layered wall construction, including a high vacuum between layers. It significantly minimizes the evaporation of cryogenic materials and contributes to outstanding thermal insulation. It has varied accessories or choices, depending on its particular use. The uses include various types of closures or stoppers, pressure relief devices, and monitoring systems to observe the temperature inside.

Safety measures are thoroughly integrated into dewar designs. It helps to manage the safe release of gas when a cryogenic liquid boils away. The flask evolved as a crucial tool to preserve ultra-cold materials in scientific, industrial, and laboratory settings. Its simple yet efficient design and exceptional insulation properties make it integral for research and experimentation.

Technical Specifications

  • Glassware for general-purpose use is suitable for the -10 °C to 100 °C temperature range.
  • Borosilicate glass containers can withstand temperatures from -150 °C to -270 °C and are available in different sizes.
  • 10-L Glass Dewar is used between -50 °C to -150 °C temperature range.
  • A 500 ml stainless steel container can sustain temperatures from -190 °C to 200 °C.
  • Cryogenic Dewar Flasks are available in varied sizes and are appropriate for temperatures between -160 °C and -200 °C.


  • Double-Walled Construction: The Dewar flask exhibits a dual-layered design comprising an inner and outer wall. It is strategically done to reduce heat transfer.
  • Limited Contact Points: The contact points between the dual walls are reduced to a minimum to diminish heat conduction.
  • Cryogenic Storage Capability: The flask excels at managing extremely low temperatures for cryogenic storage. Therefore, it is suited for substances like liquid nitrogen or liquid helium.
  • Vacuum Sealing: The space between these walls is rigorously emptied to establish a high vacuum. This helps significantly diminish heat transfer through convection and conduction.
  • Versatile Designs: It comes in various sizes and configurations, including open buckets, flasks with loose stoppers, and self-pressurizing tanks.
  • Effective Thermal Insulation: Multiple layers within the Dewar walls and a sustained high vacuum deliver exceptional thermal insulation, which helps slow down the evaporation rate of stored materials.
  • Gas Management: Precautions are considered while designing the flask to handle the gas released securely since the cryogenic liquid gradually boils away.
  • Silver Coating: To effectively block radiation heat transfer, the inner layers of the walls are covered with a silver layer.

Applications of Dewar Flask

Cryogenic Storage Dewar flasks have diversified applications across various fields. It is majorly recognized for its significance in the cryogenic processes. It is specially curated for storing and dispensing cryogenic gases like liquid nitrogen, oxygen, helium, and hydrogen. It simplifies the transmission of cryogenic liquids within factories or laboratories through portable Dewars armed with casters and handles. It insulates electronic components within wireline logging tools, ensuring their safe operation. In the medical field, it contributes to the secure storage of embryos during fertility treatments.

It is indispensable for rapidly freezing samples in research laboratories, serving as a crucial tool for scientific experiments. Vacuum flask is a variant of the Dewar flask category utilized for domestic purposes. It preserves the temperature of beverages and food, whether to keep them hot or cold for extended periods.

How to use Dewar Flask?

  • Depending on the user's requirements, select the suitable Dewar flask. The factors that must be considered are capacity, materials, and temperature requirements.
  • Fill it with a specified liquid or gas. Ensure it is filled with a cryogenic liquid for liquid nitrogen, oxygen, helium, or hydrogen applications.
  • Tightly seal the flask with a stopper or cap. This helps to prevent pressure build-ups inside the flask.
  • Be extra cautious when handling the flask, as it is delicate and easily damaged. 
  • Dispense cryogenic liquids gradually and securely using the designated flask. Ensure that a two-handed grip is maintained to handle the liquid nitrogen from controlled release safely. 

Safety Guidelines

  • Stick to the manufacturer's cryogenic vessel guidelines while handling the Dewar flask.
  • Use a small flask or a transfer apparatus for larger containers to manage cryogenic liquid securely. 
  • Avoid using liquid air or oxygen in the flask curated for nitrogen. This will help prevent combustion risks.
  • Avoid moving or bending the copper fill tube of the flask to limit its breakage.
  • Wear protective gear and ensure storage locations are well-ventilated.
  • Ensure that the flask stays upright to avoid liquid discharge and frostbite.
  • Smoking, flames, or sparks should be strictly prohibited in areas with flammable cryogenic liquids.
  • Instead of carrying the flask by its neck, use the handle provided on it to avoid accidents.
  • Plan safe routes and avoid elevators with people inside to transport cryogenic liquids. This will reduce the risk of oxygen displacement in case of spills.

Why Choose Us?

We are a proficient and well-equipped manufacturer and supplier of exceptional-quality Dewar Flasks. With over ten years of experience, we prioritize a customer-centric approach. We provide customized solutions at an affordable market price per clients' requirements. Our finest quality product offers flexibility and convenience and is best suited for research and industrial purposes. We follow all safety guidelines and are committed to delivering world-class customer service and post-sales support. We provide delivery all across the globe, so contact us now to get your tailor-made solutions.

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