Efficiency of External Gear Pump
The purpose of the research was to analyze the load characteristics of external gear pumps. As the initial data, the results of factory tests of the NMSH and SH pumps, provided by HMS Livgidromash JSC, were used. The load characteristics of the gear pump NMSH32-10 were constructed, and the dependence of this pump efficiency on the dimensionless pressure and Hersey number was given. The efficiency of the SH 40-4 pump was recalculated according to the test data. Findings of research show that for diesel fuel and oil, the calculated efficiency differs from the values indicated in the technical data sheet by more than 25%, while for fuel oil they differ slightly. This testifies to the non-monotonic dependence between the SH 40-4 pump efficiency and the viscosity. In the entire investigated range of pressures, with an increase in the viscosity of the pumped liquid, the efficiency first increases and then noticeably decreases. The paper presents the dependence of the volumetric and mechanical efficiency of the SH 40-4 pump on the Hersey number at three values of the viscosity of the pumped liquid.