"Your lab report for our refrigerator oil included the following comment: Refrigerator oils may be subject to environmental changes after removal. We therefore recommend only using our special kits of gas-tight vessels and filling them completely. Why are gas-tight vessels used and what exactly must be taken into account when filling them?"

OELCHECK offers special all-inclusive analysis kits for the analysis of refrigeration compressor oils. These kits contain gas-tight 80 ml aluminium sample vessels. They are suitable for all oil types and refrigerating agents. In addition, they can withstand the internal pressure, which can build up due to residual refrigerating agent in the sample. The sample amount is extracted via the oil outlet provided by the manufacturer in the compressor. If the sample foams quite heavily, some of the gas can be released from the refrigerating agent prior to sealing. 
However, if a synthetic compressor oil and/or ammonia is used as refrigerant, exhaust gases must be avoided!
 

The container should be completely filled and then immediately and carefully closed. These substances have a strong hygroscopic effect and can bind moisture from the air even if the contact with the atmosphere is short. Complete filling of the vessel is also important, as only partial filling allows a gas space above the sample. Outgassing can take place in these spaces. In addition, the moisture contained in the gas compartment would be absorbed by the oil. This, in turn, could distort the water determination result.