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Flow Calculations

In the following we have compiled some calculation options for you. For liquids and gases it is possible to calculate the kv value, the flow Q and the pressure drop Δp.

With the calculations for gases, one additionally distinguishes between the under-critical (p2 > p1/2) and over-critical cases (p2 < p1/2). All calculations are purely practical formulas, i.e. simplifications for the respective case, which may only be used with the specified units.

Pressure Drop Scheme

Calculations for Liquids

kv Value Calculation for Liquids

In order to calculate the kv value the flow Q, the density ρ1 of the media at the valve inlet and the pressure drop Δp across the valve must be known:

Calculations for Liquids kV



Flow Calculation for Liquids

In order to calculate the flow Q the kv value, the density ρ1 of the media at the valve inlet and the pressure drop Δp across the valve must be known:

Calculations for Liquids Q



Pressure Drop Calculation for Liquids

In order to measure the pressure drop Δp the kv value, the density ρ1 of the media at the valve inlet and the flow Q must be known:

Calculations for Liquids Δp



Calculations for Gases

kv Calculation for Gases

In order to calculate the kv value the volumetric flow QN at 1013 hPa and 0°C, the standard density ρN of the media, the pressure drop Δp across the valve, the media pressure p2 downstream of the valve and the media temperature at the valve inlet must be known:

Calculations for Gases kV under-critical

Calculations for Gases kV over-critical



Flow Calculation for Gases

In order to calculate the flow QN the kv value, the standard density ρN of the media, the pressure drop Δp across the valve, the media pressure p2 downstream of the valve and the media temperature at the valve inlet must be known:

Calculations for Gases Q under-critical

Calculations for Gases Q over-critical



Pressure Drop Calculation for Gases

Calculations for Gases Δp under-critical

Calculations for Gases Δp over-critical