German manufacturer of positive displacement pumps for high-viscosity and demanding media, based in Wolfsburg and made in Germany. History: Zeilfelder was founded in 1924 with the development and distribution of the first foam-free conveying rotary piston pump for the soap industry. A patent for screw spindles and pumps followed in 1932, the first gear pump with special gears for high-viscosity fluids in 1936, and in 1940 the first rotary piston pump worldwide for non-greasing, highly viscous media that can be heated to 450 °C. A heatable pump station with a grinder for lumpy media was developed in 1964; in 1980 the company produced gear pumps with magnetic drive for system pressures up to 100 bar for the petrochemical industry; specialised pumps for frozen media, synthetic fibres and pharmaceutical applications followed in 1984 to 1987, and in 1992 it built what was then the world's largest gear pump, for heavy oil production at 5,000 m³/h. Since 2008 the pumps have been marketed through ASM Dimatec, with the T-Rex heavy-duty pump series for biogas introduced in 2009 and a new factory opened in Wolfsburg in 2012 together with the ZH-i internal gear pump series. The range covers external and internal gear pumps and rotary lobe pumps with pressures up to 120 bar, flows from 1.5 l/h to 300 m³/h, viscosities up to 3,400,000 mPas and temperatures up to 450 °C, available in versions compliant with API, ATEX, TR-CU 10, TR-CU 12 and TA Luft on request.