Learn About R600a Refrigerant From 6 Aspects
R600a refrigerant, also known as R600a, with the English name “isobutane,” has the chemical formula C4H10. R600a refrigerant is a high-performance, new-type hydrocarbon refrigerant derived from natural ingredients.
R600a does not harm the ozone layer and has no greenhouse effect, making it an environmentally friendly option. It is characterized by a high latent heat of evaporation and cooling solid capacity, good flow performance, low delivery pressure, low power consumption, and slow temperature rise under load. It is compatible with various compressor lubricants. At room temperature, it is a colorless gas and becomes a colorless, transparent liquid under pressure. It is a replacement for R12.
1. R600a Compressor
1) Isobutane is fully compatible with traditional mineral oil and alkylbenzene oil, so there is no need to change the manufacturing process of the compressor. The cylinder volume of R600a compressors is increased by 65-70% compared to R12, with no significant change in external dimensions. Strict control is necessary to prevent leaks in R600a compressors due to the flammability of isobutane. Compressors with the same power as R12 have similar cooling capacities. Due to the flammability of isobutane, you must modify electrical components and use PTC components with seals for the start relay in R600a compressors. The compressor’s nameplate bears a flame symbol;
2) Heat exchangers designed for R12 systems, including condensers and evaporators, can be used for R600a systems with necessary adjustments;
3) Isobutane is compatible with steel, copper, brass, aluminum, chloroprene rubber, nylon, and polyvinyl chloride. These materials are consistent with the R600a system. Silicone and natural rubber are incompatible with R600a and, therefore, cannot use the R600a system;
4) Capillary tubes used in R12 systems can be used for R600a systems, with minor flow rate differences;
5) Currently used desiccants for R12 systems can also be used in isobutane systems. However, XH9 specialized desiccant recommends the use of R600a systems;
6) The charge volume for isobutane is approximately 40% of that for R12, so high-precision refrigerant charging and calibration equipment is needed;
7) Electromagnetic valves designed for R12 systems can also be used in R600a systems.
2. R600a Refrigerant Advantages and Disadvantages
Advantages:
1) R600a refrigerant has no harmful impact on the ozone layer and no greenhouse effect. It complies with the requirements of the Montreal Protocol and is considered an excellent alternative to R12 refrigerant;
2) Refrigerators using R600a have lower noise levels due to the lower operating pressure of the R600a refrigerant system;
3) The production cost of R600a is relatively low;
4) R600a refrigerant has minimal losses during production, and each refrigerator charges with a small amount of R600a, typically around 50g;
5) R600a refrigerant does not have special requirements for system materials, and the system is reliable.
Disadvantages:
1) Due to the flammability of R600a refrigerant, improper use can lead to combustion and explosions.
2) Safety measures for explosion prevention are required during the production of R600a refrigerant.
3) R600a refrigerant is unsuitable for air-cooled refrigerators and refrigerators with large charge volumes.
3. Uses of R600a Refrigerant
R600a refrigerant is known for its high latent heat of evaporation and cooling solid capacity, good flow performance, low delivery pressure, low power consumption, and slow temperature rise under load. It is compatible with various compressor lubricants.
R600a is primarily used as an ultra-low-temperature refrigerant in systems with R22, suitable for ultra-low-temperature refrigeration devices operating between -80°C and -120°C. To be a foaming agent for foam plastics and a replacement for R12 refrigerant, R-600a mainly replaces R12 and R134a refrigerants in refrigerators, freezers, and other small refrigeration equipment. Due to its flammability, it is typically used in low-charge refrigeration equipment and as a component in blended refrigerants. R600a is compatible with traditional lubricants.
4. Differences Between R600a and R134a Refrigerants
R134a, also known as tetrafluoroethane, has relatively high water solubility, which can be problematic for refrigeration systems. It can lead to corrosion and the production of acid, carbon dioxide, or carbon monoxide when combined with lubricating oil. Therefore, R134a has higher requirements for system dryness and cleanliness.
On the other hand, R600a (isobutane) is only slightly soluble in water and is compatible with materials like stainless steel, copper, aluminum, and carbon steel.
5. Can R600a Refrigerant Be Used as a Substitute for R22?
First, the types of refrigeration oil corresponding to these two refrigerants are entirely different; secondly, R600a mainly applies to low-temperature refrigeration appliances, such as refrigerators, while R22 is primarily used in some refrigeration appliances, such as air conditioners, after replacing R600a with R22, which will make the cooling effect of the refrigeration appliance significantly reduced.
If you insist on replacing it, drain all the original refrigeration oil in the refrigeration system pipeline, replace it with mineral oil, and re-vacuum it. When filling R22, you need to adjust the appropriate refrigerant filling amount.
6. Maintenance Considerations for Refrigeration Systems Using R600a Refrigerant in Refrigerators
1) Maintenance Site:
- No smoking is allowed.
- Adequate fire-fighting equipment must be available, and there should be good ventilation.
- Leak detection equipment/R600a sensors should be used if possible.
- R600a-specific ventilation equipment is required, and you must turn it on during work. Because R600a is heavier than air, the exhaust outlet should be close to the ground.
- Ventilation equipment and electrical equipment inside the site should be explosion-proof.
- The site should not have trenches or pits, and fire safety signs are necessary.
2) Maintenance Equipment:
- R600a storage tanks should be stored separately in a well-ventilated environment within the temperature range of -10 to 50°C, with warning labels.
- Leak detection equipment must be compatible with R600a refrigerant.
- R600a refrigerators should use specialized explosion-proof vacuum pumps and charging equipment, as they use different lubricating oils (R134a refrigerators use synthetic oil, while R600a refrigerators use mineral oil). Do not mix maintenance equipment between R134a and R600a refrigerators.
- The vacuum level should be lower than 10 Pa, and the charging deviation should be less than 1g.
- Tools that come into contact with the refrigerant should be stored and used separately from those used for R134a refrigerators.
3) Maintenance Techniques:
- Do not open the refrigeration system in the customer’s home.
- Verify the type of refrigerant from the compressor’s nameplate before performing maintenance on the refrigerator.
- Due to the high solubility of R600a refrigerant in lubricating oil and its low pressure, the low-pressure side of the refrigerator is usually under negative pressure. Before welding the refrigeration system, please drain the R600a cleanly. Typically, it would help if you first released R600a by opening the high and low-pressure process pipes and then using an R600a-specific vacuum pump to evacuate the high and low-pressure sides while gently shaking the compressor.
- When replacing the compressor, the refrigerant charge should be the nominal value on the refrigerator’s nameplate. If you do not return the compressor, the amount should be 90% of the little weight.
- Do not use open flames to seal the system, and use ultrasonic welding or locking.
- Must seal the joints of the replaced compressor.
- Since the low-pressure side of the R600a refrigerator operates under negative pressure, the fridge should be in the off state during leak testing.
- The temperature controller and light switch in the refrigeration compartment of an R600a refrigerator do not come into contact with the refrigerant and can be used universally with R134a refrigerators.
- R600a refrigerators use the same desiccant as R134a refrigerators, and the desiccant filter can be used universally (only for new, unused desiccant filters).
- The electromagnetic valve for R600a double capillary tube refrigerators should be explosion-proof and not mixed with R134a refrigerators.
