Answer
A person becomes a Ma?zur when, e.g. he bleeds continuously for 1 whole Salaat time and doesn’t have the opportunity to even make Wudhu and read his Fardh with complete purity.
The rule regarding him is that he should make Wudhu for the time of every Salaat. As long as the Salaat time remains, his Wudhu will remain. However, if apart from this sickness some other matter crops up, e.g. the person goes to toilet, then his Wudhu will break and he will have to repeat the Wudhu. (Bahishti Zewar)
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai