The KRT Jacket-Cooled Waste Water Pump from KSB has a fully sealed, closed-loop cooling system to keep the pump free of debris. The cooling liquid inside the jacket is an environmentally safe propylene glycol/water mix that enables the cooling system to protect the pump in temperatures as low as -4 degrees F. An impeller inside the closed loop circulates the propylene glycol/water mixture so it constantly flows around the motor gathering heat, then over a heat exchanger, which dissipates the heat into the pumped liquid. The system is designed for continuous duty completely dry or fully submerged. 804/222-1818; www.ksbusa.com.