How can I draw long line with arrow symbol in AutoCAD (I want to specify flow direction using straight line in AutoCAD 2013)

I attached here line type

2 Answer

You can use leader (some adjustments of dimension style will be required) or create a special block for that.
Also AutoCAD Plant 3D has flow arrows specially for this purpose.

Draw a pointer line in the direction desired.
Draw the first pointer at any angle from the pointer line.
With Ortho on change USC to match pointer line.
Mirror the first pointer.