What is the difference between Molecular sieve and Silica gel drier?
The non crystalline silica gel does not have as much water adsorbing capability as the Molecular sieve at the temperatures encountered in refrigeration. Also that Silica gel adsorbs some of the lubricating oil and refrigerant also in addition to the water molecules because of larger pore sizes as compared to Molecular sieve which have smaller pores and adsorb only water molecules. Further as compared to molecular sieves, silica gel has less strength and can shatter when contacted by liquid water and when subjected to repeated freeze thaw cycles. This leads to capillary chokes. Apart from the above reasons, the weight of silica gel to be used to reduce a R12 system’s moisture level will have to be about over 5 to 6 times the weight of the molecular sieve needed for the same purpose.
