Draining construction sites and protecting them from flooding

Draining construction sites and protecting them from flooding

Water on a building site costs time and money; in the event of flooding, every minute counts. The technical requirements are more demanding than the simple task of ‘pumping out water’ might suggest: fluctuating and low water levels, abrasive sand and silt, frequent continuous operation and the need to be ready for action within minutes.

Typical applications

Construction and sewage pumps keep building sites and excavation pits dry, lower the water table, drain underpasses, empty shafts, tanks and basins, and are used in flood protection and during flooding.

The key technical issue: cooling at low water levels

When draining, the water level naturally drops to close to the pump. However, many submersible pumps rely on the surrounding water to cool the motor and must not be allowed to rise too far above the waterline. The Constra construction and waste water pump solves this problem by means of a Jacket cooling: The pumped fluid flows around the Motor, cooling it even when the water level is already low. This enables continuous operation (S1) down to just above the pump sump – exactly where a drainage pump needs to operate.

Wear, Sealing and Hydraulics

Water from construction sites carries sand and silt. It is therefore crucial to have a clog-free, open multi-blade impeller as well as wear-resistant components in the impeller, pump housing and diffuser. The Motor is sealed by a shaft seal ring and a double-acting Floating ring seal in an oil bath, which reliably isolates the pumped fluid from the Motor.

Ready for use in no time

In an emergency, every second counts until the water is pumped out. A compact, lightweight design with a crane-liftable carrying handle, a control unit with a manual/automatic switch and a STORZ fixed coupling (compatible with fire hoses) make the pump portable and ready for use in a matter of minutes. When used as a fixed installation, it can be operated with a float switch or a control unit.

What it promotes – and the key limitation

The system is designed to pump clean or contaminated water containing low levels of abrasive sand and silt, up to 40 °C (60 °C for short periods). The most important operational limit: no dry running and no slurping – If the water level drops too low, there is a risk of the Motor overheating. The automatic level control prevents this from happening.

Conclusion

When it comes to drainage, it is not so much the maximum delivery head that matters as the combination of jacket cooling, wear resistance and quick commissioning. Anyone who needs to keep excavation pits permanently dry or respond in the event of flooding should select the Pump based on water level trends, sand content and the required continuous operating time.