ROTRONIC HUMIDITY FUN FACTS

Dry Ice and CO 2 in Transportation

Dry ice in general What is dry ice? In physics, the term “state of matter” is one of the distinct forms that matter takes on such as solid, liquid and gas (more exist, but won’t be viewed in this case). The best example for discus - sion is the different states of matter water can assume. In all of the above mentioned states of matter, the pressure also Dry ice is frequently used to package has an important role to play, thus items that must the temperature values discussed remain cold or in this article are only valid at a frozen during trans - pressure of 1013.25 hPa (1atm). portation, such as A state point of water exists, ice cream or biologi - where, at a certain temperature and cal samples, without pressure, all 3 states coexist. That the use of mechani - point is 0.01°C and a partial vapor cal cooling. pressure of 0.006 atm. The phe - nomenon is known as the triple point of water. S N O M M O C

A I D E M I K I W

A I V

, ] 0 C C [

S B deposition. During the sublimation O Dry ice is CO 2 in its solid phase. C A J Carbon Dioxide turns into dry ice at transition, dry ice melts and is K R

A –78.5°C (at 1 atm). The triple point directly vaporized into its gas M

Y

E of CO 2 is –56.60°C at 5.11 atm. phase. The liquid phase is only N N I

F achievable when the temperature When a matter changes directly N E

B and pressure allow it, please see from solid to gas, it is called subli - Y B mation. When the matter changes the triple point of CO 2 diagram. Triple point of Co 2 directly from gas to solid it is called continued

1 ROTRONIC HUMIDITY FUN FACTS

Dry ice used during ice is so cold, handlers should use cryogenic gloves for example. transportation? As dry ice sublimates into gas, Dry ice is often used as a coolant it is important not to pack it in a during transportation of tempera - gas tight container to avoid an ture sensitive products due to the explosion. fact that it is colder than water ice 1kg of dry ice will produce 3 and CO 2 has no liquid phase in 0.45m of CO 2 gas. Therefore it is standard atmospheric conditions. very important to monitor the When dry ice melts, it sublimates rooms where the packages are so there is only an increase of CO 2 stored or loaded/unloaded. levels and no liquid residue. As CO 2 is an odorless and col - Dry ice is used widely in the orless gas, it is very important for transportation business for both life safety to always monitor the frozen and non frozen goods. If the CO 2 level when using dry ice. CO 2 product is in direct contact with the Phase transition diagram is capable of causing asphyxiation dry ice, it will freeze. Depending on at high concentrations. the insulation used, the tempera - limate at a rate of 1% of its total In the workplace exposure limi - ture of the product can vary. mass per hour in an insulated con - tations exist: short term, 15 min - The main advantage of dry ice is tainer (14% at room temperature). utes, 15,000 ppm and long term that it has twice the cooling energy Precautions need to be taken (8 hours) 5,000 ppm. of water ice and that dry ice will sub - when handling dry ice. Because dry

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