The way to the proper valve

Designing and selecting pressure regulating valves is not a secret science mastered only by a handful of experts. The procedure described below allows the user to select a suitable valve for a particular application with relatively little effort.

The calculations based on the so-called Kv value method have been considerably simplified compared with the very complex calculations given in IEC 534; they produce, however, results which for our purposes are sufficiently accurate.

Kv value 

The Kv value is an important parameter for the performance of the valve and thus decisive for valve selection. The flow coefficient Kv (m³/h) indicates the specific volume flow rate of a valve at a determined lift (conditions: pressure loss across the valve 1 bar, medium water 5 – 40°C).

Calculation of the Kv value

The Kv value (application) is calculated from the given operating conditions of the application and allows the selection of the proper valve.

Calculation formular


valve calculation - formula for calculating the Kvs value for gases


valve calculation - formula for calculating the Kvs value for steam


valve calculation - formula for calculating the Kvs value for liquids

Comfortable to calculate the Kv and Kvs value

The calculation and design software ValvePilot assumes the task of calculating the Kv and Kvs value for you.

These values are essential for the optimal selection of valves. In addition, the programme determines the following values / parameters:

  • Noise pressure level
  • Nominal diameter
  • Reduction ratio
  • Inflow and outflow velocity
  • Phase changeover

ValvePilot also provides warnings about potential hazards such as cavitation, flashing or excessive noise pressure levels. You will also receive an alert if a pipe expansion is required owing to your operational data. Three different calculation modes Basic / Expert / Expert+ allow for a calculation tailored to your special needs.

Take advantage of the opportunity to download ValvePilot as freeware:

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