KV value is a technical term used to indicate how much fluid can flow through a valve at a given pressure drop. In other words, it's a flow coefficient - and a key factor when selecting and sizing valves and pipe components in a process plant.

When you need to ensure stable and efficient operation, it's crucial to choose components that match the desired flow. This is where the KV value plays an important role - both for the technician working with process equipment and for the buyer who needs to ensure that the solution matches the capacity and pressure requirements.

KV value - what is it?

KV value (also called Kv) is a measure of a valve or other component in a pipe system. It indicates how many cubic metres of water can flow through per hour at a pressure drop of 1 bar and a temperature of 5-30°C.

The higher the KV value, the more fluid can flow through. This means that a valve with a high KV value allows more flow, while a lower KV value restricts flow. The value is used both in the sizing phase and to compare performance between different components.

What is KV value used for?

The KV value is especially important in projects where precision and reliability of flow is crucial. It helps you find a valve that provides the right flow at a given pressure. Using a valve with the wrong KV value can lead to either unnecessary pressure loss or oversizing, which strains the system and increases energy consumption.

An example: In a food processing plant, a liquid needs to be pumped at a constant speed through a heat exchanger. If the KV value of the valve is too low, the flow is restricted and the system needs to use more energy to push the fluid through. Conversely, a KV value that is too high can cause lack of regulation and risk unstable operation.

That's why the KV value is a crucial tool in design, operation and optimisation.

How is KV value calculated?

The KV value can be calculated from the following formula:

KV = Q / √Δp

Here it is:

• KV the flow coefficient in m³/h
• Q the desired flow rate in m³/h
• Δp the pressure drop across the valve in bar

This formula assumes that the medium is water at standard temperature. For other liquids and temperatures, viscosity and density must be taken into account - often requiring technical knowledge or software.

What is the difference between KV and KVS?

The KV value varies depending on how open the valve is. Therefore, a distinction is made between:

• KV: The actual flow coefficient at a specific opening of the valve
• KVSFlow coefficient at full opening - the maximum value the valve can achieve

KVS is typically used in the datasheet as a comparable standard measure, while KV is used to assess the valve behaviour under different operating conditions. It is important to understand the difference when working with control valves and want precise control of flow.

Get advice on KV values and dimensioning

At Alflow, we meet customers every day who need help choosing the right valve for their plant. We know how important it is that components are correctly sized - both for flow, pressure and process requirements.

We offer:

• Technical advice on KV and KVS values
• Help with sizing and valve type selection
• Solutions for food, pharma and industrial production
• Documentation and quality assurance

Whether you work with CIP, steam, liquid or gas, we help you find a valve that fits your application. We believe that good advice creates better solutions - which is why you always have access to both experience and technical insight with us.

FAQ

What does KV value stand for?
KV value stands for flow coefficient, which indicates how many m³/h of water flows through a valve at a pressure drop of 1 bar. It is used to compare and dimension valves.

How do you calculate KV?
KV is calculated as: KV = Q / √Δp, where Q is the flow in m³/h and Δp is the pressure drop in bar.

What is a KV?
A KV is a unit of measurement for how much fluid a valve can flow at a given pressure drop. It is used to ensure correct sizing.

What is CV value?
CV value is the English equivalent of KV value and is used in the US and UK. It is measured in gallons per minute (GPM) at a pressure drop of 1 psi.