Vacant winter house: drain traps

Snowman9000 wrote:
Interesting tidbit about evaporation of RV antifreeze. This matches my experience, that RV antifreeze evaporates almost as soon as water.

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.

https://en.wikipedia.org/wiki/Trap_primer

:h

For over 20 years I used RV antifreeze in my cabin with never an issue of evaporation in the traps. I would let the cabin go cold though.

Currently I have a bucket mouse trap in the garage I leave all winter. It has RV antifreeze in it, with no evaporation issues to speak of. My 2c is I would not be so concern with evaporation as much as I would be with freezing temps. Not all traps are easy to get too to repair. RV antifreeze is less then $3 a gallon. Cheap insurance in my books in case of a long power outage.