A flow meter is a special tool that is used to measure the amount of fluid flowing through a pipe. It is like a ruler for water or gas that tells us how much is flowing.
Sometimes, however, the flow meter can make a mistake and give us the wrong number. This mistake is called a flow meter error. It can happen for many reasons, such as if the flow meter is not installed correctly, if there is air or dirt in the pipe, or if the flow of fluid is too fast or too slow for the meter to handle.
Just like when we make mistakes, flow meters can also make mistakes. But, if we know why and how it happens, we can fix the mistake and make sure the flow meter gives us the correct number next time.