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2. Procedure for converting an ammonia-based system running on napthenic or paraffinic mineral oils to Mobil Gargoyle Arctic SHCTM NH 68 synthetic oil. Aim: to improve the performance of the evaporators Ammonia is a refrigerant that is commonly used in the food production industry. Historically, a large number of compressors contained mineral oil but a growing number use synthetic oils that perform better at a lower temperature as the oil is no longer trapped in the evaporators and can return easily to the compressor. In addition, the thermal stability and oxidation resistance of synthetic oils outperform those of mineral oils. This procedure is only possible with Mobil GargoyleTM Arctic SHC NH 68 polyalphaolefin (PAO) synthetic oil and alkylbenzene (AB), which enable seals that were previously in contact with mineral oil to remain in place. 1 Starting up of the compressor to heat the mineral oil 2 3 Assessment of the compressor’s cleanliness and inspection of the filters 4 4b 5 Immediately monitor the condition of the oil (visual inspection): 6 6b 7 8 9 Carry out an analytical inspection of the oil after 500, 1,000, 2,000 and 5,000 hours, then once a year. 13 | PROCESS | November 2019 | Climalife contact #16 PROCESS Change the filter if it is clogged and fill the compressor with Mobil Gargoyle Arctic SHC NH 68 oil If there are any signs of contamination or if the operating parameters deteriorate, particularly if there are significant differences in the filter’s differential pressure, carefully drain the compressor and oil separator then fill with Mobil oil If the level of cleanliness is correct, fill and start the compressor with Mobil Gargoyle Arctic SHC NH 68 oil If there are no signs of contamination or if the operating parameters do not deteriorate, maintain the load of Mobil Gargoyle Arctic SHC NH 68 oil in use After 100 hours of operation, take an oil sample for analysis Check the condition of the filters. If everything is normal, go to stage 8. Replace the filters if they are clogged and repeat stage 6. After 400 hours, take an oil sample for analysis Check the condition of the filters. If everything is normal, go to stage 9. Replace the filters if they are clogged and repeat stage 6. Monitoring of the operating parameters during the transition period (pressure, temperature, filters); the filter’s differential pressure has to be checked on a regular basis. Conclusion Drain as much hot mineral oil as possible (to eliminate potential deposits) from the compressor and oil separator 10 Note: the seals and mechanical couplings would have to be changed if another type of synthetic oil is used. A change of technology, which improves energy efficiency, should not be taken lightly. Each case is different and demands a customised application procedure that is adapted to the systems and refrigerants used. Mobil and Climalife can assist you with the preparation and implementation of your projects. For your oil analyses, a periodic oil diagnostic test ("DPH A") will enable you to monitor the new technology with the support of an expert. Mobil and other similar brands are registered trademarks that belong to Exxon Mobil Corporation or one of its subsidiaries. PROOF OF PERFORMANCE An ice-cream factory in Russia was oper- ating refrigerant compressors lubricated with mineral oil. This system, which was subject to very low operating tempera- tures, had to be regularly topped up with mineral oil (up to 66 l/month for each unit with a capacity of 400 litres) and was affected by under-performance prob- lems and oil-return difficulties as the oil remained trapped in the evaporators. To ensure that the oil returns and to solve this problem, ExxonMobil’s engineers recommended the use of Mobil Gargoyle Arctic SHC NH 68 on the basis of its excel- lent fluidity when cold and specific formula that enables it to work with ammonia. Using this oil brought about the following benefits: • Reduction in the consumption of oil and top-ups. • Optimisation of drainage intervals. • No accumulation of oil in the evaporators: better oil return. It should be noted that when draining a clogged circuit and as a replacement for mineral oils, Mobil GargoyleTM Arctic SHC NH 68 oil can darken and deposits can accumulate in the filters. These phenom- ena are normal and are due to the solvent power of certain types of synthetic oil. In the case of highly clogged systems, consult Climalife’s technical department.