Designed by Dorr-Oliver expressly for handling the thickened underflow from sedimentation units. Dorrco positive displacement double diaphragm pumps are constructed of extra heavy-duty materials for tough, long-lasting service in extreme environments. These pumps can be installed at liquid level in thickener applications to prevent flooding or start-up problems. The pump operates with a smooth action, which prevents agitation and keeps the slurry from degrading during transport. Dorrco pumps come in two series: Type W and VM.