So, you have selected a pump and taken into consideration a multitude of elements - including fluid characteristics, flow rate and head, environmental and long-term optimization. But what about pipework?
Pump piping design can be overlooked when installing your new pumping system. In most cases, the focus is on the equipment. When installed with an insufficient piping arrangement, pumps can experience premature and repeated failures. In these instances, maintenance personnel repair the pump - only fixing the symptom not the true problem.
Global Pumps outline some key considerations for the pipework for your new pumping system:
Keep the suction piping as short as possible
Our team suggest a straight run pipe, approximately 5 - 10 times the pipe diameter between the pump inlet and any obstruction in the suction line. By obstructions, we mean valves and elbows.
Keeping the pump suction piping short will guarantee the inlet pressure drops as low as possible during operation. The straight run pipe will ensure a consistent velocity across the pipe diameter at the pump inlet. Together, these are important in achieving optimal suction.
Pipe diameter on the suction side to be equal or one size larger than the pump inlet
Larger pipes cost significantly more, whilst smaller pipes impose a greater friction loss on the pumping system - therefore it is a question between cost and friction loss. Global Pumps suggest installing a discharge pipe diameter that matches the discharge flange on the pump. The pipe diameter can be larger to reduce friction losses and to decrease system pressure.
A larger suction piping on the suction side is usually recommended if the liquid viscosity is greater than water. Besides this, it helps produce an even flow to the pump and avoid cavitation.
Consider eccentric reducers on the suction side
In some instances, an eccentric reducer is installed on the suction side of the pump when a pipe size transition is required.
Eccentric renders: are fitted between two different pipe diameters. They are commonly used where the diameter of the pipe on the upstream side of the fitting is larger than the downstream side.
Install the flat side of the reduced on the top, when the fluid is coming from below the pump. If the fluid is coming from the top, the flat portion of the reducer should be mounted on the bottom of the pipe. This flat portion is specially designed to discourage an air pocket from forming within the pump suction.
Eliminate elbows on, or close to the inlet nozzle of the pump
It is recommended you include 5 to 10 pipe diameters of straight run pipe between the pump inlet and elbow. This helps to eliminate the ‘sliding load’ of the pump impeller and creates uniform pump axial bearing loading.
Remove potential for air entrapment in the suction piping
It is crucial that there are adequate levels in supply tanks to eliminate vortices from forming and air entrapment. Avoid any high pockets in the suction piping - which trap air. Also, be sure to keep all pipe and fitting connections tight in suction vacuum conditions to prevent air getting into the pump.
Ensure piping arrangement does not cause a strain on the pump casing
The pumps should never support the suction or discharge piping. Any stress placed on the pump casing by the piping system can greatly reduce the pump’s life and performance.
If you can’t avoid this, you can increase the performance of the pump to make up for any piping mistakes made on the discharge side the pump. However, any errors made on the suction site can cause significant pump failures.
Want to learn more? Or maybe you’d like to discuss your application and best practice for your industry? Chat to Global Pumps today! Our team have over 40-years’ experience helping maintenance teams and project managers implement reliable and durable pumping and piping systems.
