Nibal,
The short answer here is if you are picking Manufacturer specific equipment, the radius is fixed through our data entry process. I have a call out to our RB rep to see if the 3' default we have set is good enough. Until then you are welcome to make sure to adjust the radius as needed so the system can adjust the Precip Rate as needed, and simply uncheck showing the radius column in the schedule.
Any additional insight as to what you are hoping default radius values should be, and why you need to list this in the schedule is welcome as well!
Regards,