Vacant winter house: drain traps

The evaporation rate of a liquid is directly proportional to its vapor pressure. At 25 °C the vapor pressures for water, pure propylene glycol and pure mineral oil are, consecutively, 24 torr,[2] 0.1 torr[3] and <0.01 torr.[4] Be aware though that the properties of "RV antifreeze" which has propylene glycol in it will be different than pure propylene glycol because alcohol, water and other ingredients are in it. One manufacturer of RV Antifreeze gives the vapor pressure of their product as 17 torr at 20 °C.[5] This material, if placed in a drain, will evaporate almost as fast as water. Some makers of RV Antifreeze will list the vapor pressure of their product as 0.1 or <0.1 torr. This however is only for the propylene glycol component, not the mixture that comprises their product which can be mostly water.