DEWAR Tanks

DEWAR Tanks are special vacuum-insulated cryogenic storage tanks designed for the portable and efficient storage and use of liquefied industrial gases (such as liquid nitrogen, oxygen, argon, and carbon dioxide) under low pressure. Named after the Scottish scientist Sir James Dewar, who invented the principle of vacuum insulation, these vessels have become an indispensable part of modern laboratories, hospitals, and industrial facilities. Forming a practical bridge between the cumbersome structure and limited capacity of traditional high-pressure gas cylinders and fixed microbulk tanks, DEWAR Tanks offer an ideal solution for users with medium-scale gas consumption who need flexibility and mobility in their operations. Leading companies in this field, such as Cryotanx, which manufacture to high quality and safety standards, ensure that these tanks are both safe and extremely efficient through their superior engineering designs. These systems play a critical role across a wide spectrum, from scientific research to industrial production processes, by providing continuity in gas supply, ease of use, and operational cost advantages.

Behind the extraordinary performance of DEWAR Tanks lies a fundamental thermodynamic principle developed in the late 19th century but perfected with modern technology: the minimization of heat transfer. The primary purpose of a DEWAR Tank is to maintain extremely cold cryogenic liquids, such as -196°C, in their liquid phase with a low evaporation rate, minimally affected by the ambient temperature. To achieve this, it has a complex structure that effectively combats all three main mechanisms of heat transfer (conduction, convection, and radiation).

Technically, a DEWAR Tank is a pressure vessel with a “tank within a tank” structure. The inner tank, being in direct contact with the stored cryogenic liquid, is manufactured from special materials, typically austenitic stainless steel, which do not become brittle or react with the product at these extremely low temperatures. The outer tank (or jacket) is designed more to provide structural integrity, protect the inner tank from external impacts, and house the insulation layer, and it is usually made from a more robust carbon steel or stainless steel. The most critical section between these two tanks is the insulation space. The most effective way to prevent heat transfer via conduction and convection is to create a high vacuum by almost completely evacuating the air from the space between these two tanks. This vacuum environment acts as an excellent insulator because it greatly reduces the number of molecules that can carry heat. To prevent heat transfer via radiation, the outer surface of the inner tank and the inner surface of the outer tank are polished to be reflective or are covered with multi-layer special insulation materials (Multi-Layer Insulation – MLI). These multi-layer insulation systems maximize the tank’s thermal efficiency. To ensure the vacuum is maintained for many years, special adsorbent materials called “getters” are placed inside the vacuum space to capture any gas molecules that may appear over time.

Thanks to this, DEWAR Tanks produced by Cryotanx maintain low boil-off rates even after years of use. The most important feature that distinguishes modern industrial DEWAR Tanks from a simple thermos is their integrated pressurization and distribution systems. Inside the tank, there is a circuit called a pressure-building coil. When the user wants to draw liquid or gas, this circuit takes a small amount of liquid from the bottom of the tank, vaporizes it, and directs it to the tank’s headspace (ullage space).

This process creates a controlled pressure inside the tank, and this pressure forces the liquid out. This eliminates the need for an external pump. Additionally, smart systems like the economizer circuit direct the gas directly to the use line to reduce tank pressure, especially during low-flow gas applications. This prevents the unnecessary opening of safety valves and the waste of valuable product. All these components make DEWAR Tanks an extremely efficient and user-friendly gas supply unit.

Thanks to the unique advantages they offer, DEWAR Tanks have become the standard solution for many applications where traditional high-pressure gas cylinders are insufficient or inefficient. Although high-pressure steel cylinders have been used in industrial gas supply for many years, they pose significant operational and safety challenges.

At the forefront of these challenges are capacity and logistics. A standard high-pressure cylinder contains a limited amount of gas and requires frequent replacement even with medium-scale consumption. This situation creates a continuous cycle of ordering, delivery, storage, and returns, which both increases labor costs and can lead to production interruptions. In contrast, a typical DEWAR Tank can store as much liquefied gas as 15 to 20 large gas cylinders at once. This significantly reduces the frequency of refilling, simplifies logistical processes, and provides the operation with an uninterrupted gas flow.

Safety is one of the most significant advantages of DEWAR Tanks. While high-pressure cylinders operate at very high pressures, such as 200 bar (approximately 3000 psi), DEWAR Tanks typically operate at much lower and more controllable pressures, below 22 bar (approximately 320 psi). This low operating pressure greatly reduces the risk that can arise in the event of a potential failure or leak. Furthermore, the manual handling, connection, and disconnection of heavy steel cylinders carry serious ergonomic risks and the potential for workplace accidents.

DEWAR Tanks, with their wheeled and mobile structure, almost completely eliminate these risks. From an efficiency perspective, the “heel loss” problem experienced with cylinders is solved with DEWAR Tanks. Not all the gas inside cylinders with reduced pressure can be used, and a certain amount of product is wasted. DEWAR Tanks designed by Cryotanx, however, allow for the efficient use of almost all the liquid inside. In light of these advantages, the applications for DEWAR Tanks are quite extensive.

• • Laboratories and Research: In scientific research, a continuous supply of liquid nitrogen is critical for cooling the superconducting magnets of devices like Nuclear Magnetic Resonance (NMR) spectrometers. In biological and medical laboratories, they are widely used for the frozen storage (cryopreservation) of cell lines, tissues, and other biological samples.

• • Healthcare Sector: In dermatology clinics, DEWAR Tanks offer a practical solution for cryosurgery procedures where warts and other skin lesions are treated by freezing. They are also used in some hospitals to supply small-scale central systems or to store liquid oxygen as an emergency backup.

• • Industrial Manufacturing: Small and medium-sized welding workshops can source the shielding argon gas required for precision welding processes much more efficiently with DEWAR Tanks compared to cylinders. The pure nitrogen required for processes like laser cutting or electronic parts assembly is also supplied by these tanks.

• Food and Beverage: Gourmet restaurants or bars can source the gas needed to make nitro coffee or cocktails from these tanks. Boutique ice cream producers can use liquid nitrogen from DEWAR Tanks for instant freezing processes.

DEWAR Tanks play an extremely flexible and efficient role in a business’s gas supply strategy. The operational lifecycle of these tanks includes; correct selection, safe use, periodic filling, and regular maintenance. Each step of this process is critically important for gaining maximum benefit from the system and maintaining the highest level of safety. Selecting the right DEWAR Tank for a business is the first and most important step. Several key factors must be considered when making this choice.

First, the type of gas to be used (Nitrogen, Oxygen, Argon, etc.) must be determined, as each gas has its own specific properties and some tank accessories can be customized accordingly. Second, the tank’s capacity (e.g., 180 liters, 240 liters, or larger) must be determined by analyzing the business’s average weekly or monthly gas consumption. A tank that is too small will require frequent refilling, while an unnecessarily large tank can mean an unnecessary initial investment cost and higher static evaporation losses. Third, the outlet pressure required by the application must be identified. Cryotanx, by offering DEWAR Tanks with different pressure setting options, can develop special engineering solutions for all types of application needs.

The tank’s operation and filling must be performed by trained personnel. The filling process is usually done from a larger cryogenic storage tank (such as a microbulk tank or tanker) via a special, insulated, and flexible hose. During this process, it is mandatory to use personal protective equipment such as protective gloves and goggles against cryogenic burns and cold surfaces. Although DEWAR Tanks are extremely durable and reliable vessels, they require regular maintenance and periodic inspections for a long-lasting and safe operation. Chief among these inspections is checking the vacuum level. If the vacuum level deteriorates over the years, this situation increases the evaporation rate, reducing efficiency.

When necessary, the vacuum may need to be re-established. Testing the system’s most critical safety components, the safety valves, at specific intervals and replacing them when necessary, is the fundamental requirement for the tank’s safe operation. It must be ensured that the pressure and level gauges are working correctly, and the wheels and other mechanical parts should be checked regularly. Cryotanx positions itself not just as a supplier for the DEWAR Tanks it sells, but also as a solution partner. In addition to providing consultancy to its customers on selecting the right tank, it also offers safe use training, periodic maintenance services, and technical support. This holistic service approach ensures that users get the highest efficiency from their DEWAR Tanks system and can continue their operations trouble-free for years.

In this way, an investment in a DEWAR Tank transforms into a long-term, reliable, and profitable solution for the business.