BVA HAND REFRACTOMETER Style:Ester Tester Graph paper While these items can be it won t corrode While these items can be used for a number of purposes this configuration is particularly good for the mounting of Evaporators in Cool Rooms & Freezer Rooms due to the following features: Premium pre insulated annealed copper pair coils used for general air conditioning and refrigeration installations and split system air conditioners Unlike chemical test kits that don't work on all esters The BVA Ester Tester is a simple and safe way to determine the percentage of mineral oils remaining in a compressor when changing over to a Polyol ester oil as part of a retrofit from R12