Bilfinger

is required. Sometimes the pump can overheat due to running dry for extended periods or experiencing a power supply voltage drop. In this case, thermal motor protection is a must for the pump. Good casing size is another important factor when selecting the right pump. Typically, the inside diameter of dewatering well casing is 20 cm, 30 cm or 40 cm (8", 12", or 16") in construction. These are common sizes of PVC and steel pipes available from typical manufacturers. It is crucial to select the right pump size to fit inside the good casings with enough clearance to manoeuvre during installation and removal. Slimline designed pumps are commonly used for these operations. However, depending on the inside diameter of the good casings, different designs can be utilized. Individual pump control panels are also standard equipment for the operations. The pump controls have automatic features that can sense the water level and turn the pump on and off as necessary to maintain water levels while conserving energy and allowing the pump to operate only when needed. Depending on the operations, it is essential to decide if an auto-control panel is required.

What are some of the main pitfalls of a good dewatering operation?

JD: Electric submersible pumps need constant steady power with the proper voltage and amperage capability. It is important to make sure there is a reliable power source, whether a line drop from the power company or gas/ diesel-powered generator(s). An improper power supply can damage the pump motors and cause failure. Abrasive particles passing through the good slots in large quantities may cause pumps to wear out prematurely. The impellers and other wear parts, as well as the outer casings and motor housings, can wear thin and cause complete and catastrophic failure. This is one reason that proper well slot sizing is critical. It’s also important to perform routine maintenance to help mitigate issues that can arise in these harsh applications. Allowing the pumps to run dry for extended periods can damage the pump physically. The electric motors use the water passing over the outside of the motor housing to dissipate heat and may also overheat if no water is present. This is one of the reasons proper level control panels are critical in temporary good dewatering. If power cables become damaged, water may get into the pump and ultimately into the motor compartment, which will cause the electric motor to short out and possibly burn up. This is a common issue when lowering and handling the submersible pumps on a construction or mine site. Adequate strain relief on the power cable and a separate lifting rope or cable installed on the pump will reduce the chances of damage. Our network of expert dealers can guide customers through all these considerations to ensure they precisely receive the right pumps. The Tsurumi team is also always ready to help.

Tsurumi Pumps, +27 (0) 82 404 4743, yentl@tsurumipumpsafrica.com, www.tsurumipumpsafrica.com

Bilfinger Intervalve Africa (Pty) Ltd. is one of the enterprises in Bilfinger Power Africa (Pty) Ltd., the South African subsidiary of German based Bilfinger SE. For years, we have been adding value to the power, mining, paper pulping and broader industry through comprehensive valve supply, valve maintenance and heat treatment solutions. www.intervalve.bilfinger.com