For example, if it is determined that friction losses are equivalent to five feet of head for fluids of "water-like viscosity," the vertical distance of the centrifugal ^'imp suction above the liquid level cannot exceed ten feet. When pumping viscous fluids, the pump suction should be below the "suction tank." In other words, the head that moves fluid from the fluid level in the suction tank to the pump is the "total suction head." The "total discharge head" tends to resist the flow of liquid from the pump to the discharge tank.
Static head. Static suction head is the height of the liquid surface in the suction tank above the centerline of the pump. If the liquid surface is below the centerline, the static suction head assumes a negative value, referred to as "suction lift."
Static discharge head is the height of the highest liquid surface in the discharge section above the centerline of the pump. This can be liquid in the discharge pipe or in the discharge tank, depending on which is highest.
Surface pressure. The suction and/or discharge compartments may be under pressure other than atmospheric. Both suction and discharge surface pressure is converted to feet of liquid.
Friction head. Friction head is the energy necessary per pound of fluid pumped to overcome friction and turbulent losses as fluid flows through the system. The values of suction friction head and discharge friction head depend on pipe lengths, diameters, flow rate, valves and fittings, their configurations, and pipe materials and interior finish.
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