Nominaalvool

Nominaalvool, or nominal flow, is a term used in fluid dynamics and engineering to denote a reference or design flow rate at which a device or system is rated. It represents a standard point on a performance curve, used to characterize how equipment like pumps, valves, or heat exchangers will behave under typical operating conditions. The concept provides a concise way to compare equipment and to specify performance in catalogs, datasheets, and system designs.

The nominal flow is not necessarily the actual operating flow. Real systems may operate above or below Qnom depending on process requirements. Manufacturers usually specify Qnom together with corresponding head, pressure drop, efficiency, and other parameters at design conditions, such as a particular fluid, temperature, and viscosity. This helps engineers select components that will meet required performance under expected operating scenarios.

Calculation and determination: Qnom is typically determined from the manufacturer's performance curve or from applicable standards. For pumps, Qnom is often defined at the best efficiency point (BEP) or at a defined design point; for valves, it corresponds to a standard nominal Cv at a set pressure drop. In practice, Qnom assumes the use of a standard fluid (e.g., water) at a reference temperature, allowing comparison across devices. In operation, actual flow is measured and compared with Qnom to assess performance and efficiency.

Notes: The term is a design concept used across industries and may have slight variations in definition between manufacturers and standards. It should not be confused with maximum or minimum flow; it is a reference value. Changes in temperature, pressure, or viscosity can shift performance away from nominal values. Standards and datasheets specify the exact conditions for Qnom.