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## Main Question or Discussion Point

Two questions;

1)

I'm struggeling to understand the concept of the Cv or Kv value, also known as the flow factor. In SI units this is defined as the flow through a valve (m3/h) at a pressure drop of 1 bar, or 100 kPa. Fair, and the formula for calculating it is easy enough. I enter my flow and the desired pressure drop (in this case 5 kPa). So where does this "1 bar" enter the picture?

2)

To measure the flow through a valve one connects a meter to it (called a CBI, made by Tour & Andersson). I always hear people saying that the valve needs to have a certain pressure drop in order for the flow to be measurable. Why is that? I always considered pressure drop as something one wants to avoid...

1)

I'm struggeling to understand the concept of the Cv or Kv value, also known as the flow factor. In SI units this is defined as the flow through a valve (m3/h) at a pressure drop of 1 bar, or 100 kPa. Fair, and the formula for calculating it is easy enough. I enter my flow and the desired pressure drop (in this case 5 kPa). So where does this "1 bar" enter the picture?

2)

To measure the flow through a valve one connects a meter to it (called a CBI, made by Tour & Andersson). I always hear people saying that the valve needs to have a certain pressure drop in order for the flow to be measurable. Why is that? I always considered pressure drop as something one wants to avoid...