Gear Pumps GHP Series Information 12 Once the pump flow rate has been selected, different flanges, shafts, inlet and outlet port position and type are available to suit most applications. In the product tables, the flow, shown at 1500 rpm, has been evaluated using a value of volumetric efficiency of 95%. All the drawings represent pumps with clockwise rotation. Reversing the direction of rotation also involves reversing of the suction side with the delivery side ports. The following diagrams show, for each single displacement, the typical required power as a function of rotation speed and pressure generated by the system and allow you to easily spot the product suitable for your application. Calculate hydraulic power (P), delivered by amotor subject to a pressure differential between input and output as follows: Dp = pressure differential [bar] Q= flow rate [litre/min.] Apump requires energy, just like any other hydraulic machine. Part of this power is given to the fluid to increase pressure required by the circuit, the remaining part is used to cure pump internal friction. Therefore, for proper pump operation, supplied torque shall be higher than theoretical torque. P= (Q •Dp) / (600 •htot) [kW] htot = total pump efficiency (hhm •hvol) Contact jbj Techniques technical office, email: info@jbj.co.uk or telephone: +44 (0)1737 767493 for further details on efficiency. The proper values for flow rate, torque and supplied according to pressure differential, rotation speed and set test conditions, can be found on thePerformance Curvepages. These pumps are hydraulic machines converting mechanical power into hydraulic power. This section deals with rotary positive-displacement pumps. In this type of pump, a given volume of fluid flows from inlet to outlet at each shaft rotation (theoretical displacement). Pressure depends on delivery line resistance to fluid flow. As gear pumps only transfer fluid, they are subject to pressure generated by the circuit. Therefore, if system flow rate and motor rotation speed are known, it is easy to select the right pump displacement and its model. Absorbed power Values for hvol andhhm (and consequentlyhtot) depend on pressure differential between supply and delivery, rotation speed, fluid features (temperature and viscosity) and filtering degree. The diagram indicating flow rate variations according to speed and pressure, shows that not all the theoretically available fluid is transferred from inlet to outlet because of pump internal leakage. Leakage can be greatly reduced through pressure axial compensating systems (as described at the beginning of this catalogue) but never eliminated. Leakage increases as circuit pressure increases. www.jbj.co.uk/gear-pumps.html #DriveLineHarmony
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