Section 01 Alternatives to HCFCs in the Refrigeration and Air Conditioning Sector 44 S tatistics from a database of 1000 oil samples from retrofitted systems showed a very clear correlation between two factors and successful retrofits. Systems with a low humidity level in the oil and low degree of contaminants would give reliable operation whereas systems with both high humidity and presence of contaminants would have a high likelihood to have a rapid breakdown. The interaction between moisture and contaminants was obvious, so it is worth trying to ensure clean and dry systems as far as possible (Herbe Lars, 1997). It is easy to apply a simplified retrofit procedure with minimum requirements and in most cases there will be no immediate effects of operating with ester oils with high concentrations of mineral oil. Some systems will run well even in the long term if the oils are of good quality, the system is 1.6.7 Methods of oil analysis and moisture content in oil 1.6.8 LabLaboraratory tests 1.6.9 Refrafractometer test 1.6.10 Test kit dry and oil transport is easy. In the other systems where the old oil contains some acid or/and moisture and working at high temperatures may be expected, a failure is very likely. Sight-glasses have an indicator for moisture, but old sight glasses for CFCs and HCFCs cannot be expected to be reliable for new oils and refrigerants, so whenever possible a change of sight glass should be evaluated. Test kits to detect moisture in refrigeration systems are available from suppliers of servicing equipment. There are also three commonly-used methods to analyse how much of the old mineral or alkylbenzene oil remains in the system after oil change. Th e most accuraurate and reliable method is to send samples to a laboratory. This is associated with a cost but this cost is minimal as compared to a compressor failure or losses of goods that a work standstill can cause. Laboratories doing oil tests for the industry are often capable of testing an ester oil for the remains of mineral oil. For these tests one sample of the old oil and one of the pure new oil as references are needed. These tests also often include a test of the moisture level in the oil A refrafractometer is an easy-to-use tool that can determine in the field the level of mineral/Alkyl benzene oil in an ester oil. which is a key parameter for long term chemical stability of the system. These oil laboratories also offer analysis of equipment wear which is valuable to evaluate the status of larger equipment before decisions on repair, retrofit or replacement are taken. Note that oil samples should never be exposed to ambient air as they absorb moisture (in particular ester and PAG oils). Careful sampling procedures are important and proper sample bottles must be used. Contact oil laboratories for advice. Fig. 1.13 Refractometer is an excellent tool to measure remaining mineral oil content in the field. By comparing a sample of the clean ester oil with a sample taken after oil change the level of mineral oil can be determined. S ome suppliers of oil and service equipment offer test kits where you add a sample taken after oil change and get a pass or fail indication. These kits are typically specific for a particular oil and will not give a correct result on other oils. 1.521.511.501.491.481.471.461.451.441.521.511.501.491.481.471.461.451.44RefractiveIndexnD