This is a highly practical and reliable calculator which can be simply used for calculating the volume flow rate of a fluid which also is defined as volume of fluid that is passing through a given cross sectional area per unit time. The term cross sectional area is often used to describe the area through which something is flowing.
Here you can find tables with the approximate water flow in a pipe by size.
The recommended maximum velocity for water flow in residential areas is typically 8 feet per second (8 ft/s). This recommendation is based on various factors, including the need to minimize pipe erosion, reduce noise from flowing water, and avoid potential pressure drops that can occur at higher flow velocities.
Commercial Reverse Osmosis
AXEON LP-500: Reverse Osmosis System Optimized for Light Commercial Applications
Commercial Water Softeners
96,000 Grain Dual Tank Water Softener with The Digital Fleck 9100SXT valve
Filtration Systems By Contaminants
3 Stage Water softener with Clack WS1CS Control Valve
Commercial Reverse Osmosis
Pro Series 300 GPD Reverse Osmosis System
Commercial Reverse Osmosis
GRO 6-Stage-UV Reverse Osmosis Installation Kit with Pentair 50 GPD Membrane 1:1 and UV Filter