Set Limit on Purchase Quantity

1

Can we limit the total quantity of an item that can be purchased for a project ?

Explanation:
Just like budget, I want to set a limit on how many quantities of each item can be purchased for a project.
Is such a feature available out of the box in ERPNext ?

2

feature is not yet, but you can easily set using the server script.

3

Use Material Request to freeze the quantity(and tolerance is possible.). Based on MR, PO can only be made upto relevant qty .