ForConstructionPros.com

Selecting the best dewatering solution requires experience and an understanding of the physics involved. For optimum performance and equipment life, it's important to choose the correct type and size of pump, as well as set it up for the application.

Sizing pumps should be a science, not guesswork. "Trial and error is not suggested, but it is not an uncommon method in contracting pump rentals," says Mark Trumble, business development manager for RSC in LaPorte, TX.

Many parameters influence an effective pumping system. According to Dale Conway, vice president of engineering, Thompson Pump & Mfg., you need to understand the required flow, pressure, solids size, suction lift, altitude, specific gravity, viscosity, temperature and fluid type.

"If the product is water, then use suction lift and discharge elevations as a bare minimum estimate," advises Trumble. Then account for any losses in the system. "The TDH (Total Dynamic Head) is then created by adding friction losses from the distance pumped, as well as all valves, fittings and equipment downstream which have resistance to the suction and discharge."

"The longer the discharge run of the hose, the more the friction loss. The more friction loss you have, the less flow," explains Jim Widrick, construction equipment sales manager, Gorman Rupp. "So you really want to minimize how much friction loss you have through the hose." Keep in mind that all pumps are limited to a maximum suction lift of about 28 ft.