S R C C Alternatives to H F s in the efrigeration and Air Conditioning Sector ection 01 41 Th e first method to remove the mineral oil from the system and replace it with ester oil was to conduct repeated oil changes. The advantage of this method is that all servicing technicians are familiar with how oil is changed. There are also some obvious disadvantages: The oil is expensive.■■ It is often time consuming to travel repeatedly to the site ■■to do the oil changes. During the oil change process, the new ester oil is mixed ■■with a sometimes heavily contaminated mineral oil and may start deteriorating quickly. During the oil change, the system is normally run on the ■■old refrigerant until the mineral oil content is sufficiently low. During that time viscosity of the ester oil can decrease due to excessive miscibility with CFC or HCFC. Th ere are flushing units/methods designed to circulate the “old” refrigerant through the system and bring the oil and contaminants to the flushing machine, which is also a recycling unit that can separate the contaminants before the cleaned refrigerant is re-injected again (fri3oil). With properly trained technicians, this method has proven to effectively clean refrigeration systems to low levels of mineral oil in a limited period of time, thus reducing the number of oil changes required. In many systems, levels of 1-2% of mineral Th ere are severaral flushing agents available on the market often based on HFCs or HCFCs. As these are controlled substances it is important to ensure what national regulations stipulate on their use. There can be national regulations controlling the use of these substances as solvents and how to handle the material after use. Some flushing units are developed to separate contaminants from the solvent used to facilitate repeated reuse of the solvent 1.6.3 Retrofit with the “oil chahange method” 1.6.4 Retrofit through flushing with the “old” refrigerarant 1.6.5 Retrofit through flushing with a solvent An often discussed issue is how many oil changes are required to achieve a given target for mineral oil content. Sometimes different sources generalise the number of oil changes more or less regardless of system design, which would result in very different results. It is important to adapt the number of oil changes to what is needed to achieve the targeted mineral oil content. As discussed in section 1.6.2 the target should be set first and then appropriate method to achieve it should be selected. The number of oil changes required can vary between one and seven or more, depending on methods and system design. Oil changes and the flushing methods below can also be used in combination with each other to achieve the most cost effective retrofit. oil can be achieved in one flushing. In systems with 10-20 kg of refrigerants this can often be done in less than one or two hours. This method can also be used to flush the system after compressor burnout. After the flushing is completed the mineral oil will be separated from the refrigerant that is also recycled. In some markets this has been a commonly used method to retrofit R-12 and R-502 systems during the CFC phase out.(Honeywell, 2009) and adapted flushing units that separate oil from the flushing agent so it can be reused (Ekotez). After flushing, the solvent will be contaminated with chlorine-contaminated oil and must be handled in accordance with national regulations on waste products. If the waste product needs to be exported for proper handling, the transports need to be done with appropriate permits from the authorities of the exporting, transit and importing countries.