We are installing a fire protection system in a 20 floor ( 04 towers ) building , and we do have a common pumping station at basement, in addition 04 independent terace fire tank provision is made at each tower, my doubt, since we have common pumping station at basement, pressure in all 04 tower is same at all time, we have pump controle panel at basement, if a internal standpipe in tower A, 20th floor is operated same amount of pressure loss would happen in tower B aswell , how do we make sure the terrace pump of perticular tower is started on loss of pressure.

( Availabe preesure switches are all analog type , and not precise on setting )