Power requirement at duty point can be worked out by multiplying the duty point pressure with unit hp.& adding no Load viscous power of appropriate viscosity to this. Safety margin may be provided before fixing the rating of the pri-mover. For higher viscosity further margin may be kept or the manufacturer may be consulted. All sizes of ‘HGSX’ pumps are designed to run at 1440 RPM up to viscosity of 500 CST, however small size pump up to 1″ can be run at 1440 RPM safety, even at higher viscosity up to 1000 CST but with additional horse power, for higher sizes reduce the speed to 960 RPM. For viscosity above 1000 CST. speed is require further to avoid cavitation & over loading consult our expert.