Feed pipe must be fully submerged in the tank or vessel. If it’s too close to the surface of the fluid, the suction creates a vortex, drawing air (or other vapors) into the liquid and through the pumping system.More Points to be Taken Care while Designing Pump Suction Piping In these cases, use an inline flow conditioner or straightener. Sometimes due to space constraints, it’s just not possible to make provision for a sufficient settling distance in the pipework before the pump. A number ranging between five (5) to ten (10) suction pipe diameters of straight pipe run is typically the recommended value in published technical literature.
Max 7 gswitch more inlets install#
viscosity changes etc), then it would be prudent to install as many as ten suction pipe diameters of straight piping next to the reducer inlet flange. In case several improperly specified parameters come into the equation (e.g.
The concept is simple though, ensure stable and uniform flow onto the impeller eye. This results in fewer pump failures over the life of the pump due to vibration caused by flow induced turbulence. Fully open, non-flow disturbing valves, vaned elbows and reducers are not considered flow disturbing fittings.” This standard eliminates any reference to the possible flow distribution that could be generated by the reducer. Any form of turbulence reduces efficiency and increases wear and tear on the pump’s bearings, seals and other components.ĪNSI/HI 9.8 American National Standard for Pump Intake Design (P21, 1998) states, “There shall be no flow disturbing fittings (such as partially open valves, tees, short radius elbows, etc.) closer than five suction pipe diameters from the pump. Pumps, and especially centrifugal pumps, work most smoothly and efficiently when the fluid is delivered in a surge-free, smooth, laminar flow. In case of long horizontal pipe runs, air pockets are avoided by installing the eccentric reducer with the flat side up. When the source of supply is above the pump, then the eccentric reducers must be placed with the flat side down. When the source of supply is below the pump, then the eccentric reducers must be placed with the flat side up. Concentric reducer is recommended for vertical inlet (suction) piping or horizontal installations where there is no potential for air vapor accumulation. This configuration prevents air pocket accumulation at the upstream end of the reducer. Eccentric Reducers InstallationĮccentric reducer is recommended for horizontal flow to the pump. The right pump suction pipe size is a compromise between cost (bigger pipes are more expensive) and excessive friction loss (small pipes cause high friction loss and will affect the pump performance).
Also the flow being reached at the pump inlet or impeller will not be of uniform velocity profile causing various issues discussed above. Suction pipe size smaller than the pump’s inlet size will increase the frictional losses that will further increase the power required by motor to drive the pump. Suction pipe size must never be smaller than the pump’s inlet nozzle size. For the same flow rate, if we increase the line size, fluid velocity as well as frictional losses decreases. Greater the area of pipe, lower is the velocity, lower frictional loses (higher NPSHa), lower is differential pressure generated by the pump and there by lower power required by motor to drive the pump.
Max 7 gswitch more inlets full#
Then why don’t we use a pipe of same size as that of suction nozzle?īecause we want minimum frictional losses in pipe and full bore flow to the impeller eye. The best solution is to use an eccentric reducer orientated to eliminate the possibility of air pockets. A reducer fitting is typically used in pump suction piping to reduce the size of the suction pipe to match the size of the pump suction end flange. A reducer is a constriction and requires careful design to avoid both turbulence and the creation of pockets where air or vapour might collect. It’s standard practice to employ suction-side piping one or two sizes bigger than the pump inlet.