Saughöhe

Saughöhe refers to the maximum vertical distance a pump can lift a fluid from its source to the pump's inlet under specific conditions. This is a crucial parameter in pump selection and system design, particularly for centrifugal pumps. It is not to be confused with the total discharge head, which is the total vertical distance the fluid is pumped from the source to the discharge point, including all friction losses and pressure heads.

The saughöhe is determined by several factors, including the vapor pressure of the fluid at the pumping temperature, the atmospheric pressure, and the friction losses within the suction piping. If the pressure at the pump inlet drops below the vapor pressure of the fluid, cavitation can occur. Cavitation is a phenomenon where vapor bubbles form and then collapse, leading to noise, vibration, and potential damage to the pump impeller.

Therefore, the net positive suction head available (NPSHA) must always be greater than the net positive suction head required (NPSHR) by the pump to prevent cavitation. The NPSHA is a measure of the absolute pressure of the liquid at the pump inlet, less the vapor pressure of the liquid, all expressed in terms of head. The NPSHR is a characteristic of the pump itself, indicating the minimum pressure required at the inlet to avoid cavitation. Understanding and properly calculating saughöhe and NPSH are essential for ensuring the reliable and efficient operation of pumping systems.