The 408 Double Valve Pump (DVP) is a gas drive pump suitable for low flow and medium flow applications of almost any depth and narrow diameters. It is available in 316 stainless steel in 1.66" or 5/8" diameter (42 mm or 16 mm) and in PVC in 1.66" (42 mm).

Compressed gas supplied from the Controller pushes down on the water column in the drive line, which is at static level, closing the check valve at the base of the pump, forcing water up the sample line. When operated properly, “drive gas” will never come in contact with the sample water, which produces high quality VOC samples.