Ice cold dependability
Complete turnkey solutions safeguard valuable specimens

For many years, cryobanks have been state-of-the-art systems which are used to preserve valuable specimens in an unaltered state for long periods. To handle large specimen volumes, a number of super-insulated storage tanks are assembled to create a cryobank which can be installed as a turnkey system at the customer site.

The inert properties of liquid nitrogen (boiling point –196°C at ambient pressure) have made it the ideal coolant for use in the preservation of biological specimens. A number of super-insulated storage tanks can be assembled to create a cryobank.
The available space at labs and institutes is often very limited, or in some cases the need to install a cryobank does not arise until a later date, making it difficult to find suitable space for a traditional cryobank. Cryotherm, a subsidiary of Air
Liquide Deutschland, offers turnkey cryobanks mounted in lab containers which are designed to address this problem. These containers hold the cryo equipment plus the electrical and heating systems, and they are suitable for outdoor installation. These well-engineered units make best possible use of the available space.
A storage tank holds the coolant, and systems are provided to help safeguard, document and manage the cryobank. The 20 foot container is supplied complete with supply and storage tank, electrical systems, heating, windows and ventilation.

A wind screen or airlock can be mounted at the entrance. A warning light, which signals a low oxygen level in the container, is located outside near the door to prevent access when the alarm has been activated.
The container can hold up to nine Biosafe 400 specimen tanks, which have a capacity of 200,000 2 ml specimen micro tubes or 2,600 50 ml specimen bags. The Biosafe tanks are available as a standard version and as a medical product certified to Class IIA requirements as defined in EU directive 93/42/EEC. Storage vessels must always be medical products if the specimens stored in them are intended for return to humans (e.g. sperm specimens to be used for artificial insemination). On both versions, the quality of the tanks, dependable fill level monitoring and complete documentation ensure that specimens are not damaged at temperatures which remain below –130 °C.
Super insulated transfer lines are required to supply liquid nitrogen to the specimen tanks. These vacuum insulated lines are made entirely of highly corrosion-resistant, cryogenic steel.
Optimized vacuum technology
The vacuum technology has been optimized to provide many years of fault-free operation. The evaporation rate in these lines is only 0.010 kg/(m·h), which is
40 times less than the evaporation rate of traditional insulated lines. Cryosafe fittings are mounted at the liquid nitrogen outlets. They create an insulating steam buffer between the uninsulated outlet and the super insulated transfer line. The steam buffer prevents the outlet from icing up in the quiescent state. Every outlet
also has a cut-off valve, so that the specimen tanks can be released if necessary. Cryotherm’s Sirius 1000 is a 1,000 liter storage tank for liquid nitrogen which is designed specifically to supply cryobanks. The tank is installed at the highest point on the cryobank (on the container). The tank acts as a phase separator, too. A phase separator is needed, because small amounts of the liquid nitrogen evaporate. To ensure that only the liquid phase is
supplied to the specimen tanks, the liquid is drawn from the bottom of the tank. The gas collects at the top of the tank and is released into the atmosphere. Gas that is generated in the lines is automatically fed back to the storage tank, and it is released into the atmosphere as well. Nitrogen is extracted from the tank through a vacuum insulated fitting. The Sirius 1000 operates at 3 bar overpressure and builds up
pressure automatically for discharge. The pressure level can be pre-selected. To
comply with TRB 801 (German Pressure Vessel Ordinance), the tank has safety mechanisms that prevent excess pressure during filling operations. The filling valve closes automatically if the pressure reaches a critical value during filling. Large
diameter exhaust and overflow lines are provided for fast filling by the liquid nitrogen service.
Cryotherm uses a dual-track safety design. Equal emphasis has been placed on human safety and specimen integrity. A few precautions must be taken during handling of liquid nitrogen which is extremely cold. The extreme low temperatures and the oxygen displacement properties of liquid nitrogen can create a hazard. The cryobank in the container has active ventilation and a system to warn against insufficient oxygen levels. If the oxygen level in the container falls below a preset threshold, an alarm is triggered and the active ventilation starts automatically. Any nitrogen gas inside the container is quickly replaced with air from the outside. As an option, the main cut-off valve on the tank can be closed. All vessels and lines have super vacuum insulation to avoid a hazard from the extremely low temperature of the liquid nitrogen. Full-stroke safety valves prevent excessive buildup of pressure caused by evaporation of nitrogen in spaces that can be sealed off.
Dependable level monitoring
The level of the liquid nitrogen must be kept within predefined limits to maintain the integrity of the specimens. An Adur ß level controller in combination with a
level probe and a magnetic valve ensure that the specimen temperature always remains below –130°C. The Adur ß provides dependable level monitoring regardless of pressure fluctuations, and it controls the level so that it always remains between preset limits. If the level ever exceeds the upper or lower limits, alarm signals are activated at the controller’s floating outputs, which can optionally be used to shut off the main valve. The Biosafe Control monitoring system measures, tracks and saves the temperature in the Biosafe cylinder. It also monitors and saves the filling cycles and all of the alarm messages from the fill level controller. The devices on all Biosafe systems (up to 32 units) can communicate with each other and record the measurement results. Software is supplied which can be used to download data from internal memory to a PC at regular intervals. Biosafe control software provides various options for data analysis and monitoring of the cryobank. Users can maintain complete documentation of all events in the cryobank, giving them a reliable quality trail for the specimens.