Dry Ice
Definition of Technical Terms
Dry Ice
Dry Ice
Definition 1: Solid carbon dioxide (CO2), white. Under -78.5°C and atmospheric pressure, it sublimates into a gas. It is widely used as a cold cloud catalyst in artificial weather modification.
Applicable Disciplines: Atmospheric Sciences (Level 1 Discipline); Atmospheric Physics (Level 2 Discipline)
Definition 2: Solid carbon dioxide.
Applicable Disciplines: Aquaculture (Level 1 Discipline); Preservation and Processing of Aquatic Products (Level 2 Discipline)
Molecular Weight: 44.01
Density (solid) 1560 kg/m³ (-78°C)
Melting Point -57℃
Freezing Point -78.5℃
Molecular Model of Dry Ice
Three-phase point - 56.6°C, 5.17 x 10^5 Pascals
Critical Point 31℃ 7.37 x 10^6 Pascals
Properties
Colorless and odorless gas with an acidic taste.
Solubility
Soluble in water (1:1 by volume), partially forming carbonic acid.
Liquid to Gas Ratio: 8.726 SCF (Gas)/LB (Liquid -17.8°C, Pressure 21 kg/cm²)
Liquid to Solid 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 and naturally exists in the air. Although carbon dioxide makes up a relatively small percentage in the air (about 0.03% by volume), it is one of the important gases we recognize. Dry ice is highly volatile, sublimating into a non-toxic, odorless gas—carbon dioxide—thousands of times larger in area than the solid. Therefore, dry ice should not be stored in airtight, small-volume containers as it can easily explode. It is safe to keep dry ice in a well-ventilated area, allowing the gas produced by its sublimation to dissipate.
At room temperature and under a pressure of 6079.8 kPa, carbon dioxide condenses into a colorless liquid, which then rapidly evaporates under low pressure, forming tightly packed, ice-like solid masses.
Its temperature is -78.5°C, which is dry ice. Dry ice has more than 1.5 times the cooling capacity of water ice, absorbs heat and sublimates into carbon dioxide gas, leaving no residue, no toxicity, and no odor, with sterilizing properties. It is affected by heat
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 low-temperature state.
At room temperature, when carbon dioxide gas is pressurized to approximately 101325 Pa, it will freeze into a snowflake-like solid form when a portion of the vapor is cooled to around -56°C. The sublimation heat of solid carbon dioxide is veryAt -60℃ it measures 364.5 J/g, and when it vaporizes under normal pressure, it can lower the surrounding temperature to about -78℃, without producing any liquid, hence the name "dry ice."Dry ice can also be used for artificial precipitation. It can rapidly absorb a large amount of heat from the air, causing the surrounding temperature to drop quickly and allowing water vapor to condense into tiny droplets, thereby achieving the purpose of precipitation. Additionally, substances like silver iodide (AgI) etc.Similar in nature.
Application Scope
Dry ice applications in the electronics industry
Clean internal grease and dirt in cleaning robots and automated equipment; remove integrated circuit boards, soldering flux after welding, contaminated coatings, resins, solvent-based coatings, protective layers, and photosensitive corrosion inhibitors on printed circuit boards. Applications of dry ice in the field of refrigerated transportation.
Low-temperature transportation for medical freezing applications, as well as special drugs such as plasma and vaccines.
Transportation for electronic low-temperature materials and precision components, both short and long distance.
Transportation and preservation of high-end food products such as premium beef and mutton.
Due to these properties of dry ice, it has been used in recent years by some computer overclock enthusiasts to cool and overclock CPU/GPU processors. Impact records.
Price
Prices vary as dry ice is a common refrigerant, with specialized chemical factories in major cities selling it for 10-15 yuan per kilogram, which is still acceptable for enthusiasts. Common types of dry ice include 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 also purchase food-grade dry ice from these food sales departments. Dry ice available in the market usually comes in block, granular, or powdered forms. In overclocking, granular or powdered dry ice is used, and it's best to avoid buying blocks, as large pieces are very hard to crack.
Be cautious when handling dry ice at all times and always use thick cotton gloves or other protective gear to touch it! Prolonged direct contact with the skin can cause cellular freezing and injuries similar to mild or severe burns. Dry ice should not be used in areas like car interiors or cabins, as the sublimated carbon dioxide can displace oxygen, potentially causing shortness of breath or even asphyxiation!
Do not let children handle dry ice alone!!
2. Dry ice is extremely cold; do not place it in your mouth to prevent frostbite!!
3. Always handle dry ice with thick cotton gloves, clamps, or other protective items (plastic gloves are NOT effective in blocking!!)
4. Use dry ice in a well-ventilated area; absolutely avoid keeping it in a sealed space with dry ice!!
Do not mix dry ice with liquids.
Warning: Use dry ice properly and safely to avoid injury.
When using dry ice at high frequencies, be aware that it sublimates very quickly at room temperature and pressure; if not used promptly, it can vanish quickly, especially in summer. A 20-kilogram box of dry ice can completely sublime after being placed in a room at room temperature for 24 hours. Before using dry ice for cooling during high-frequency operation, there are two important reminders: first, ensure good ventilation in the room, and second, wear protective gloves. Dry ice is a low-temperature substance, so safety must be a priority 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 people believe that filling the entire chamber with dry ice will provide better cooling, but it also leads to a lot of condensation, which can cause accidents if it drips onto circuit boards. In reality, once the processor reaches a stable operating state, there is a temperature equilibrium point where cooling and heat dissipation occur. Adding too much 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 damage to the skin and tissues of a body part due to prolonged exposure to cold temperatures.
Symptoms
The skin feels very cold and may turn slightly red before frostbite occurs.
The skin first loses its color, but as frostbite gradually forms, it may turn pale, grayish yellow, or have spots.
May blister. It might hurt a bit, or you might not even realize you're frostbitten.
Initial symptoms of frostbite (frostnip) include stinging, followed by numbness and stiffness, with the affected area appearing pale; it can be completely restored if warmed immediately. If the initial frostbite is not treated, it progresses to superficial frostbite, where the skin and subcutaneous tissue have already necrotized, the skin remains pale or slightly gray, feeling cold but soft; after thawing, it becomes red and painful, and large blisters similar to second-degree burns form within one to several days; after several more days, the blisters dry out and form black eschar, which will eventually be replaced by new skin if no infection occurs.
Cold Injuries Treatment Measures
Move to a warm area and keep the affected area in a warm, dry environment. Remove any constrictive items to prevent them from being difficult to remove during swelling. Keep the affected area warm by placing it in gradually adjusted warm water (38.8~40.5 degrees). Do not expose dry ice to cold again; elevate the affected area to alleviate pain and swelling, then wrap the area with clean gauze and seek medical attention; the aim of first aid is to restore the frozen body fluids to normal. Therefore, if the surrounding area of the affected area can be warmed, it can be cured quickly. Do not immerse the affected area directly in hot water or use fire to warm the area, as this may worsen frostbite. Since massage can cause complications, do not massage 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 differentiate it from other cleaning processes. The major benefits include its applicability, environmental friendliness, practicality, cost-effectiveness, and safety for the client's specific dry ice cleaning solutions.
Dry Ice Cleaning Technology Applications
Dry ice cleaning technology involves rapidly freezing the material to be cleaned, causing it to form microscopic cracks. Dry ice then forcibly enters these cracks, rapidly expanding and forcing the material to be cleaned off. Therefore, 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 "combined cleaning techniques," such as traditional methods like cleaning dirt with degreasing agents, acid washing to remove rust from metal surfaces, and thinning paint with solvents.
However, from an industrial practicality standpoint, the application of dry ice cleaning technology is related to the national environmental awareness and legal requirements, meaning that when traditional processes fail to meet environmental standards, dry ice cleaning can be used as a substitute for conventional cleaning methods. From a process perspective, the principle of any cleaning process is to ensure that the cleaned items are not damaged and to maintain their integrity. Dry ice cleaning must also adhere to this principle. Dry ice cleaning involves spraying dry ice particles in a mist form onto the surface of the item, which must withstand a certain amount of wind pressure. If the item's surface cannot endure such pressure, dry ice cleaning should not be employed.
Dry ice cleaning is widely used in the fields of nuclear energy, metallurgy, casting, petrochemicals, rubber, plastic, shipbuilding, automotive, food, pharmaceuticals, machinery, printing, electricity, and electronics...
Cost of dry ice cleaning
Can dry ice cleaning technology replace traditional cleaning processes? Another key issue is the cost of the process, which necessarily ties into the consumption of dry ice, pressure levels, and flow rates, and 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 main materials for dry ice cleaning are 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 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 matter of great concern for users. In fact, the consumption of dry ice is closely related to the cleaning conditions and precision. For heavy oil stains with strong adhesion, such as paint, scale, carbon deposits, and welding slag, the removal requires deep freezing and effective impact to cause the material to crack and peel layer by layer. As a result, the ice consumption necessarily increases, as does the requirement for air pressure, and the cost accordingly rises. However, for oil stains with less adhesion, powerful compressed air is not needed, and low-pressure cleaning can be used, significantly reducing the dry ice consumption and lowering costs accordingly.
Additionally, the key feature of dry ice cleaning is its speed. Dry ice has a high volatility, making slow operations impossible, and it also has a high stripping speed, thus achieving rapid cleaning. Secondly, dry ice cleaning is a "dry cleaning" process that does not produce any conductive medium, preventing any residue from damaging the device. Therefore, it is the preferred method for items that are not suitable for "wet cleaning." Most importantly, dry ice cleaning does not generate secondary pollution, eliminating the need for recycling and processing of cleaning media, significantly reducing costs.
As for the final destination of the material being removed, since dry ice cleaning is a physical cleaning process, theoretically, the material being cleaned is only stripped away and does not disappear.
The destination of the debris removed by dry ice cleaning
