Dry Ice

Tech Term Definitions

Dry Ice

Dry Ice

Definition 1: Solid carbon dioxide (CO2), white. It sublimates into a gas at -78.5℃ and atmospheric pressure. Widely used as a cloud-seeding agent in artificial weather modification.

Applied Disciplines: Atmospheric Science (First-level Discipline); Atmospheric Physics (Second-level Discipline)

Definition 2: Solid carbon dioxide.

Applicable Discipline: Aquaculture (First-Level Discipline); Fish Preservation and Processing (Second-Level Discipline)

Molecular Weight: 44.01

Density (solid) 1560 kg/m³ (-78°C)

Melting Point -57℃

Freezing point -78.5℃

Molecular Model of Dry Ice

Triple Point - 56.6°C 5.17E+5 Pascals

Critical Point: 31°C, 7.37 x 10^6 Pascals

Property

Colorless, odorless gas with an acidic taste.

Dissolution Condition

Soluble in water (1:1 volume ratio), partially forms carbonic acid.

Liquid to Gas Ratio: 8.726 SCF (Gas)/LB (Liquid -17.8°C, Pressure 21 kg/cm²)

Liquid to Solid Conversion Ratio 0.46 (-17.8℃) 0.57 (-48℃)

Dry ice is the solid form of carbon dioxide, which is an odorless and colorless gas under normal conditions, naturally occurring in the air. Although carbon dioxide makes up a relatively small volume (about 0.03%) in the atmosphere, it is one of the important gases we are aware of. Dry ice is highly volatile, sublimating into a non-toxic, odorless gas that is 1000 times larger in surface area than the solid carbon dioxide. Therefore, dry ice should not be stored in containers with good sealing and a small volume, as it can easily explode. It is essential to place dry ice in a well-ventilated area to allow the gas produced from its sublimation to be released for safety.

At room temperature and a pressure of 6079.8 kPa, CO2 is condensed into a colorless liquid, which then rapidly evaporates under low pressure, forming tightly packed solid ice-like substances.

Its temperature is -78.5°C, which is dry ice. Dry ice has over 1.5 times the cooling capacity of water ice, absorbs heat and sublimates into carbon dioxide gas, leaving no residue, toxicity, or odor, and has sterilizing properties. It is heat-resistant.

Dry ice sublimates directly without liquefying. It is the solid form of carbon dioxide, and due to its extremely low temperature of -78.5°C, it is often used to maintain objects in a frozen or低温 state.

At room temperature, when carbon dioxide gas is pressurized to approximately 101325 Pa, and a portion of the vapor is cooled to around -56°C, it will freeze into a snowy solid form of carbon dioxide. The sublimation heat of solid carbon dioxide is veryLarge, at -60℃ it is 364.5 J/g, and when it sublimates under normal pressure, it can lower the surrounding temperature to around -78℃, and it does not produce any liquid, hence the name "Dry Ice."Dry ice can also be used for artificial rainmaking. When placed in the air, it quickly absorbs a large amount of heat, rapidly lowering the surrounding temperature, causing water vapor to condense into tiny droplets, thereby achieving the purpose of precipitation. Additionally, substances like silver iodide (AgI) etc.Similar properties.

Application Scope

Dry ice applications in the electronics industry

Clean internal oils and dirt from cleaning robots and automated equipment; remove soldering flux, contaminated coatings, resins, solvent-based coatings, protective layers, and photosensitive anti-corrosive agents on printed circuit boards; and the application scope of dry ice in the field of refrigerated transportation.

Transportation of low-temperature frozen medical products, including plasma, vaccines, and other special pharmaceuticals.

Electronically低温 materials, long and short-haul transportation for precision components.

Transportation of perishable high-end food products, such as premium beef and mutton.

Due to the properties of dry ice, it has been used in recent years by some computer overclocking enthusiasts to cool and overclock CPU/GPU processors. Impulse records.

Price

Prices vary as dry ice is a common refrigerant, with specialized chemical factories in major cities offering it for 10-15 yuan per kilogram, which is still acceptable for enthusiasts. There are various types of dry ice, including food-grade, medical-grade, and industrial-grade. Food-grade dry ice is commonly used for cooling food and is widely used in bars and restaurants, slightly more expensive than industrial-grade. If industrial-grade dry ice is unavailable, you can purchase food-grade dry ice from these food sales departments. Dry ice available in the market usually comes in block, granular, or powdered forms. For overclocking, granular or powdered dry ice is used, and it's best to avoid buying blocks, as large pieces are very hard to crack.

Always handle dry ice with care and use thick cotton gloves or protective gear! Prolonged direct contact with skin can cause cellular freezing and injuries similar to minor or severe burns. Do not use dry ice in enclosed spaces like car trunks or ship cabins, as the sublimated carbon dioxide can displace oxygen, leading to shortness of breath or even asphyxiation!

Do not allow children to come into contact with dry ice alone!!

2. Dry ice is extremely cold; do not place it in your mouth, and prevent frostbite at all costs!!

3. Always handle dry ice with thick cotton gloves, clamps, or other protective materials (plastic gloves do not provide adequate insulation!!)

4. Use dry ice in well-ventilated areas; absolutely do not place dry ice in a confined space with other items!

5. Dry ice should not be mixed with liquids.

Important Reminder: Use dry ice safely and properly to avoid injury.

When using dry ice at high frequencies, be aware that it sublimates very quickly at room temperature and pressure. Not using it promptly can result in it disappearing quickly, especially in summer when a 20-kilogram box of dry ice can completely sublimate after being placed in a room at room temperature for 24 hours. Before using dry ice for cooling at high frequencies, there are two important reminders: first, ensure good ventilation in the room, and second, wear protective gloves. As dry ice is a low-temperature substance, safety must be maintained during use; the pain from frostbite can be as severe as that from burns. Additionally, pay attention to the amount of dry ice added. Many believe that filling the entire cannon with dry ice will provide better cooling, but it can lead to a lot of condensation, which, if it drips onto the circuit boards, can cause accidents. In reality, after the processor enters a stable operating state, there is a temperature equilibrium point for cooling and heat dissipation, and adding an excessive amount of dry ice will not lower the processor temperature further. Experienced extreme overclockers can master this balance point well, achieving good cooling effects with less dry ice.

Frostbite Symptoms and Treatment Measures

Frostbite Definition

Frostbite refers to the injury of the skin and tissues in a body part due to prolonged exposure to cold temperatures.

Symptoms

The skin feels extremely cold and may appear slightly red before frostbite occurs.

The skin will first lose its color, but as frostbite gradually develops, it may turn pale, or grayish with a yellow tinge, or white with spots.

May develop blisters. Could be painful, or you might not even realize you're frostbitten.

Initial symptoms at frostbitten areas (frostnip) are tingling, followed by numbness and stiffness, with the affected area appearing pale; warming it up can lead to complete recovery. If the initial frostbite is not treated, it can progress to superficial frostbite, at which point the skin and subcutaneous tissue have necrotized, the skin remains pale or slightly gray, feeling cold but soft; after thawing, it may turn red and painful, and large blisters similar to second-degree burns may form one to several days later; after a few more days, the blisters dry out and form black eschars, which, if no infection occurs, will eventually be replaced by new skin.

Cold Injury Treatment Measures

Move to a warm area and keep the affected area in a warm and dry environment. Remove any constrictive items to prevent them from being impossible to remove during swelling. Place the affected area in a gradually heated warm water bath (38.8-40.5°C) to maintain warmth. Do not expose dry ice to cold temperatures again; elevate the affected area to alleviate pain and swelling, then wrap the area with clean gauze and seek hospital treatment; the purpose of first aid is to restore frozen body fluids to normal. Therefore, if the surrounding area of the affected area can be warmed, healing can occur quickly. Do not immerse the affected area directly in hot water or use fire to warm the area, as this may worsen the frostbite. Due to the risk of exacerbation caused by massage, avoid massaging the affected area.

Caution --- Do not massage, bake, or puncture blisters to prevent infection of the affected area.

As we know, dry ice cleaning can also be referred to as dry ice blast cleaning, CO2 cleaning, or low-temperature cleaning. The characteristics of dry ice cleaning technology distinguish it from other cleaning processes. The major benefits include its applicability, environmental friendliness, practicality, cost-effectiveness, and safety, making it a suitable solution for customers.

Dry Ice Cleaning Technology Applications
Dry ice cleaning technology involves freezing the material to be cleaned to form micro-cracks without altering its chemical properties, then forcing dry ice into these cracks, where it rapidly expands to dislodge the material from its surface. Thus, it is classified as a "physical cleaning method." Theoretically, dry ice cleaning can replace traditional physical cleaning processes such as sandblasting, water jetting, and wiping.

Dry ice cleaning technology can also replace certain "mixed cleaning techniques," such as traditional methods like cleaning oil stains with degreasers, acid washing to remove rust from metal surfaces, and diluting paint with solvents, which involve a combination of physical and chemical processes.

However, from the perspective of industrial practicality, the application of dry ice cleaning technology is related to the national environmental awareness and legal requirements; that is, in cases where traditional processes fail to meet environmental standards, dry ice cleaning technology can be used to replace conventional cleaning methods. From a process standpoint, the principle of any cleaning process is to ensure that the workpiece being cleaned is not damaged, thus maintaining the integrity of the workpiece. The dry ice cleaning process must also adhere to this principle. Dry ice cleaning involves spraying dry ice particles in a mist-like form onto the surface of the workpiece, which must withstand a certain amount of wind pressure. If the workpiece surface cannot bear this wind pressure, dry ice cleaning cannot be used.

Dry ice cleaning is widely used in the nuclear energy, metallurgy, casting, petroleum, chemical industry, rubber, plastic, shipbuilding, automotive, food, pharmaceutical, machinery, printing, power, and electronics industries...

Cost of dry ice cleaning

Another critical issue in determining whether dry ice cleaning can replace traditional cleaning processes is the cost of the process. This inevitably ties into the consumption of dry ice, pressure levels, and flow rates, as well as the resulting cost implications. However, the process cost of any cleaning method is directly related to the original condition of the item being cleaned and the required cleaning precision. Different cleaning precision requirements and conditions can lead to significant cost variations.

Firstly, the raw materials for dry ice cleaning mainly consist of dry ice and compressed air, with an endless supply of compressed air that requires no transportation, thus eliminating the costs associated with procurement and shipping of raw materials. The primary raw material is dry ice. The cost of dry ice is calculable, as 3.0 tons of liquid carbon dioxide can produce 1 ton of high-quality dry ice.
The consumption of dry ice is a major concern for users. In fact, the consumption of dry ice is closely related to the cleaning conditions and precision. For heavily soiled, strongly adherent substances like paint, scale, carbon deposits, and weld slag, they must be removed through deep freezing and effective impact to cause the substances to crack and peel layer by layer. This necessarily increases the amount of dry ice used, along with higher air pressure requirements and increased costs. However, for substances with less adhesion, such as light oil stains, strong compressed air is not needed. Low-pressure cleaning can be used, resulting in significantly less dry ice consumption and a substantial reduction in costs.

Additionally, dry ice cleaning is characterized by its speed. Dry ice has a high volatility, making slow operations impossible, and the stripping speed is also high, thus achieving fast cleaning. Secondly, dry ice cleaning is a "dry clean" process that does not produce any conductive medium, preventing any residual conductive material from damaging the device, making it an optimal choice for items not suitable for "wet cleaning." Most importantly, dry ice cleaning does not generate secondary pollution, eliminating the need for recovery and treatment of cleaning media, which can significantly reduce costs.

As for the ultimate destination of the material being removed, since dry ice cleaning is a physical cleaning process, theoretically, the material being cleaned is only stripped away from the object and cannot disappear.

The disposition of the material removed by dry ice cleaning