What is a scale and why do you use it?

Scale is defined as a system or series of marks used for measuring or registering. An example of scale is what someone would use to figure out the length of something. An example of scale is what someone would use to find out how much they weigh.

Explanation:

a saline water is fed to a reverse osmosis unit at flow rate o rotameter connected to reject (retentate) line reads 8 installed in reject and permeate line reads 15.2 milli siemens/cm and 300 micro siemens/com respectively.