When pumps are located above the water level as in pumping from a river, there is a negative NPSH. To overcome this problem engineers install a foot valve to prevent the water column from draining away from the pump inlet. However sometimes the foot valve leaks and pumps cannot start. Arasains Indonesia supplies the Johnson Combiprime for negative suction heads, a truly self priming pump. This pump has its own built in vacuum pump to remove air when starting the pump. This vacuum pump has a large air displacement capacity shortening start up time. This pump is suitable for low viscosity clean fluids, especially when self priming is required. Self priming is up to 8 m and max water temperature is 80°C. A sea water resistant version is available. Maximum capacity is 800m3/hr at 100m head.