I as far as distance from the palm tree trunk, generally, as long as the sprinkler spray reaches within 1 foot of the truck. It depends how far the sprinkler sprays. I would not place it very close.

What is your clmate and zone is also a consideration. Is it dry and do these palms like it somewhat dry or damp etc..

I am in South San Francisco Bay area, so last few weeks were very wet, but next rain should be in October :)