This daemon will delete any particle without neighbours after the specified time and is limited to standard particles. With grid fluid particles you will not see any effect. It is sometimes needed to keep fluids coherent, accelerate a simulation or create clean meshes. Isolated particles can slow down a simulation significantly!
This field specifies the maximum isolation time in seconds [s], and after this time the particle is deleted. Unlike "k Age", here the time unit is seconds, not frames. Therefore it will be adjusted automatically if “FPS output” changes. Just as a memory hook: if you do not know whether a time-depending parameter expects frames or seconds, just have a look at the default value. Frames are always integers, e.g. 5 or 210, while seconds are floats with decimals, for example 4.25 or 6.5.