There is a draw by *perpetual check*, but it is not enforced the same
way that the repitition of moves is.
What I mean is, repeating a position 3 times allows the player to
claim, and be legally granted, a draw. You cannot draw merely by
checking an opponent, however many times, unless you reach the 50
move rule (which I don't believe is enforced on this site). Draw by
perpetual check works this way: One side checks the opponent and
creates a position where their repeated checks cannot be stopped by
the opponent. The opponent realizes this, and concedes to a draw
rather than continuing ad nauseum.
The point is, there's no such thing as a 9-check draw *rule*. The
perpetual check is a device used by (usually, the losing) player to
*force the opponent to concede to a draw*, NOT an automatic draw
by the rules of chess.
Hope this helps.