Dewars storage

Glass Dewar flasks for small-scale storage should be in metal containers, and any exposed glass taped to prevent glass fragments flying in the event of fracture/implosion. 

Hazards in addition to those taken for hydrogen gas should be taken when handling or storing LH2. Therefore, any LH2 splashed onto the skin or into the eyes can cause frostbite burns or hypothermia. Vents and valves in storage vessels and dewars may be blocked by accumulation of ice formed from moisture in the air. Excessive pressure may then result in mechanical failure with jet release of hydrogen and potentially in BLEVE. 

Some confusion exists in the terminology regarding liquid helium (LHe) containers. In the following, we shall call dewars the storage and the transport containers, and cryostats the cryogen containers used in experiments. Because of their large capacity (typically... 

Very practical for measurement between 4.2 K and room temperature are the so-called dipstick cryostats, designed for insertion into storage dewars (typically 5 cm neck diameter). Construction details of an insertable cryostat are reported in ref. [7],... 

Fig. 5.4. Evaporation cryostat for temperatures T > 4.2 K. A mixture of gaseous and liquid 4He is transferred from the storage dewar to the cryostat by means of a transfer tube. The mixture is pumped through a spiral tube which is first thermally anchored to the experiment chamber. The temperature of the experiment can be...

The essential features of the earlier commercial models were that the two piston engines were vertically arranged inside the large finned heat exchanger in a static atmosphere of helium with LHe from the Joule-Thomson expansion collecting in the bottom of the dewar. This liquid could be either used in situ or transferred to all external storage dewar. The energy of expansion was absorbed in a crosshead on top of the dewar assembly. 

Dewar flask tests, adiabatic storage tests (AST)—see Section 2.3.2.2, and... 

These tests can also be used to evaluate the induction time for the start of an exothermic decomposition, and the compatibility with metals, additives, and contaminants. The initial part of the runaway behavior can also be investigated by Dewar tests and adiabatic storage tests. To record the complete runaway behavior and often the adibatic temperature rise, that is, the consequences of a runaway, the accelerating rate calorimeter (ARC) can be used, although it is a smaller scale test. 

Modem Dewar flask equipment includes an adiabatic shield, a compensation heater, and a computer to provide for control and for data acquisition and analysis. An example of the application of an advanced design is the adiabatic storage test (AST) [120,121]. In the AST, the heat generated at nearly adiabatic conditions by the reacting or decomposing substances is determined as a function of time. 

The stability of powders can be determined by adiabatic storage tests or Dewar flask tests under an air atmosphere (Section 2.3.2.2). Several other dedicated tests have been developed [10,133-136]. 

Remove a batch of frozen cells from liquid nitrogen storage dewar. 

Once secured in a cryovial, the processed samples are placed on cryocanes, which are placed into a liquid nitrogen Dewar vessel for storage. 

Storage Dewar 3. The ctyotongs (with enclosed crystal) is rapidly lifted off... 

Screening The carousel containing the crystals to be screened is removed from the storage dewar and placed into the dewar of the MarCSC samplechanging robot. A protocol file that contains the screening parameters for each crystal is generated automatically by extracting the necessary... 

Smith, D. P. E., and Binnig, G. (1986). Ultrasmall scanning tunneling microscope for use in a liquid-helium storage dewar. Rev. Sci. Instrum. SI, 2630-2631. 

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