Dry ice is the solid form of carbon dioxide (CO2) occurring at the temperature of -78.5 °C. Mechanical engineers and artisans commonly use dry ice in a process referred to as shrink fitting (also known as freeze fitting).
Shrink fitting is commonly used in engineering to fit together bearings, collars, shafts and other components which require an interference fit.
Dry ice is commonly used in civil engineering for pipe and valve repairs. If a stop valve or isolating valve is not available in a section of the pipe where repairs are needed, or a joint needs to be inserted, dry ice can be used to stop the flow of the water. By using dry ice, it is possible to freeze the water inside the pipe, so the pipe can be cut or repaired without a continual flow of water to hamper the work.
Refrigeration emergencies can be caused by power failures or refrigeration compressor failures. Dry ice is a quick, cost-effective and safe solution to this problem. Dry ice can be placed on top of the frozen product so that, as the dry ice sublimates, the CO2 vapour falls onto the product and keeps it chilled or frozen. This will allow the refrigeration technician sufficient time to complete the repairs efficiently.
When moulded rubber or plastic components are produced, they commonly have thin “flashes” of material or mould marks where the two halves of the mould join. Mould trimming by hand is time consuming. No detrimental effects result from the process and all of the components’ physical attributes are retained once they have returned to ambient temperature.
Cold traps are used in many scientific and manufacturing applications to collect evaporated liquids and prevent them from moving throughout a process. The cold trap provides a very low-temperature surface on which such molecules can condense. Dry ice is used to create the extreme cold required to condense these vapours, capturing them in liquid form and preventing them from contaminating instrumentation and plant, such as vacuum pumps.
In certain process applications, it is useful to be able to quickly cool, chill or freeze materials within a process. Dry ice can be added directly onto the material or it can be mixed into the batch. The temperature of the product is reduced as the dry ice sublimates.
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