I'm trying to stop using plastic in my brewing and tought that it was a good idea to "No Chill" in sanke kegs (type "S" spear) instead of my old HDPE containers. But I dont' know if the valve will hold the negative pressure that the no chilling process create.
The valve will let the outside air come in? Or maybe the keg will knead to the inside with the vacuum? Please report your experience doing that or tell me ways to make it safe.