Submersible dewatering pump selection
Submersible dewatering pumps are vital in construction, mining and quarrying applications enabling users to remove water, sludge, and slurry. Here, this article outlines the main considerations for specifying reliable submersible pumps.
Construction managers and engineers are increasingly under pressure to increase efficiencies across their sites and they can make huge gains by using the right equipment for the job, so getting the correct specification for a reliable submersible pumps can make all the difference.
Drainage water clean water or water containing small solids such as sand or clay with a solid weight of approximately 10% and particle size up to 1.27 cm diameter.
Sludge Viscous mixture of liquids and solids, including soft wet mud and by-products of industrial or refining processes. Sludge has a solid weight of approximately 40% and particle sizes up to 5.08 cm diameter. Slurry semi-liquid mixtures typically loaded with sediment and fine particles of materials such as manure, cement, or coal. Slurry has a solid weight of approximately 70% and particle sizes up to 6.35 cm diameter.
The higher concentration of solids is best handled by slurry pumps which are specially designed for handling corrosive and abrasive media. If the liquid is particularly aggressive then ensure the pump is robust and designed with protection features such as hardened, clog-free impellers, and wear-resistant. However, if the fluid to handle contains solids with a size below 50 mm a sludge pump, such as Atlas Copco’s WEDA S50, will be better suited for the job.
For the best value and efficiencies, the pump selected should be able to handle the flow requirements with enough capacity to cope with fluctuations in water level as well as versatility to manage the demands of different sites. A pump which is over-specified and can handle a much higher flow capacity will be unnecessarily expensive and will not provide the most cost-effective solution. On the other hand, a pump that has been under-specified will struggle to transport the media and wear out more quickly, resulting in a shorter life span.
If the suction lift required for dewatering with a surface pump is more than approximately seven metres, a submersible pump should be considered instead. Designed to be totally submerged, it uses the proximity and pressure of the surrounding water to aid fluid movement through the hose and therefore less energy is needed to move the water. When specifying, check the manufacturer’s published pump curve, which shows head height against flow rate, to ensure it covers the required duty point.
If the site is remote and prone to a fluctuating mains supply consider a pump whose motor and starter are equipped with inbuilt electrical protection against varying voltage, phase failure and human error.