The Model 811LF pump incorporates a circular concentric volute casing in conjunction with a radial vane impeller making flow capacities down to 4 gpm with heads up to 920 ft possible. The low-flow pump also reduces excessive radial loads and minimizes the shaft vibration and deflection, which can lead to extended mean time between preventive maintenance operations. Class 150 raised-face (RF) flanges are standard on pump Models LF1.5x1-8AA and LF2x1-10A05, while Class 300 RF flanges are standard on pump Model LF3x1.5-13A20.When operating in reduced-volume conditions, the 811LF’s radial vanes provide better hydraulic control than traditional ANSI impellers, Griswold says. The manufactured-in balance holes also reduce both axial thrust and seal-chamber pressure.The low-flow pumps are ANSI-dimensional so that they can be installed without piping or base changes to existing equipment. The 811LF case and impeller can be retrofitted to an existing Griswold pump.