# Result Table - Centrifugal Pump

The available results that are listed in the table vary depending upon the visible properties that you have selected. Figure 1 shows the normal or default rows. You can choose the rows you wish to display in the results table via the Set Visible Results Dialog. Figure 1: Available results for a centrifugal pump. Only descriptions for the default results are shown in this section. If you wish to see the definition for other values click here. -- ID -- (aka User Number): All flowsheet elements have a unique number that is assigned by FluidFlow. It is not possible for the user to change this number because it is used as a unique identifier by the scripting module. Node numbering starts from 1, incrementing upwards, and pipe numbering starts from -1, decrementing downwards. Composition Mass %: This is the fluid mass composition that remains constant throughout the pump. FluidFlow determines the composition because an individual component mass balance is carried out at each node. Duty Efficiency: This is the efficiency that the pump will operate at the duty point. If pump data contained in the database does not include efficiency values then n/a will appear in this row. Duty Flow: This is the flow that FluidFlow has calculated that the pump will deliver when it is placed in your system. When you place a pump in any pipe system there will always be one unique flow that will occur, and this is called the duty flow. Any centrifugal pump will always operate on its performance curve, the position of the duty flow point is determined by the intersection of the system curve and the pump capacity curve. Duty NPSH Available: This is the net positive suction head available at the pump suction. The available NPSH depends on the design of the suction piping and is not related to the type of pump you are using. Duty NPSH Required: This is the net positive suction head that the pump requires. The pump manufacturer has determined this value with respect to pump cavitation. You should always ensure that the NPSH available is greater than that required. Typically a safety margin of 0.5m is used. Duty Power: The pump shaft power needed to drive the pump. In practice the total power needed will be greater, because the shaft power does not include any losses in the transmission train or driver. Duty Pressure Rise: This is the head that will be developed by the pump at the duty flow. A centrifugal pump, in any fixed system will always deliver the same head irrespective of the fluid being pumped. The delivered pressure will always be different as this depends on the fluid density, which of course changes with each liquid. The example in Figure 2 below shows a calculated pump duty pressure rise of 12.8 m fluid for a system transporting water from an inlet and outlet which have a head value of 11.2 and 10.2 m fluid respectively. The pressure loss in pipes -1 and -2 are calculated as 0.1 and 13.7 m fluid. The pump duty pressure rise in this case can therefore be established from: 10.2 - 11.2 + 13.7 + 0.1 = 12.8 m fluid (no change in elevation in this system). Figure 2: Pump Duty Pressure Rise. In Stagnation Pressure: The stagnation pressure at the pump inlet. This is the sum of kinetic and pressure energies (static pressure + velocity pressure). Stagnation pressure is the pressure a flowing fluid would rise to if brought isentropically to rest, converting its kinetic energy to enthalpy. In Stag. Temperature: This is the stagnation temperature at the pump inlet. The stagnation temperature is the temperature that the fluid would reach if it were brought to rest isentropically, converting its kinetic energy to enthalpy. In Static Pressure: This is the pressure that acts equally in all directions at the point in the fluid and is present irrespective if the fluid is flowing or if the fluid is at rest. The pressure inside any element is not the static pressure, unless there is no flow. Stagnation pressure is the flowing pressure. In Static Temperature: The static temperature at the element inlet. Static temperature is related to stagnation temperature (ignoring work, heat exchange, and potential energy) by the equation T 1 = T 1 0 - 0.5 v 1 2 / C p In Velocity: The velocity at the pump inlet. This is often different to the outlet velocity because typically pump suction size is larger than pump discharge size. Out Stagnation Pressure: The stagnation pressure at the pump outlet. This is the sum of kinetic and pressure energies (static pressure + velocity pressure). Stagnation pressure is the pressure a flowing fluid would rise to if brought isentropically to rest, converting its kinetic energy to enthalpy. Out Stag. Temperature: This is the stagnation temperature at the pump outlet. The stagnation temperature is the temperature that the fluid would reach if it were brought to rest isentropically, converting its kinetic energy to enthalpy. Out Static Pressure: This is the pressure that acts equally in all directions at the point in the fluid and is present irrespective if the fluid is flowing or if the fluid is at rest. The pressure inside an element is not the static pressure, unless there is no flow. Stagnation pressure is the flowing pressure. Out Static Temperature: The static temperature at the element outlet. Static temperature is related to stagnation temperature (ignoring work, heat exchange, and potential energy) by the equation T 2 = T 2 0 - 0.5 v 2 2 / C p Out Velocity: The velocity at the pump outlet.