there is an age limit?------or are you referring to a Christian sect that wants the object of baptism to KNOW WHAT HE IS DOING? I have known hinduswho attended catholic schools (in india and not baptized)
In the Catholic faith, there is no age requirement for baptism. In many Catholic schools, there are no sacramental requirements. In some there are. This is up to the individual private school.
People have different conceptions and perceptions of Baptism. Some believe it is a statement of commitment that one makes when one becomes of age (or reaches the age of reason). Some believe it is a sacrament of initiation where one is welcomed into the family of Christ, and has family and sponsors to guide them in the teachings of Christ. There are sources outside of scripture that tell us infant baptism was a fact in the early Church.