Dust clouds can be ignited by electrostatic discharges. Several methods for determination of Minimum Ignition Energies, MIE, and Linear Minimum Ignition Energy Densities, MIED, of dust involve metres. The use of a new fluidized bed ignition chamber with adjustable spark gap shows that MIE and MIED have minimum values gap shows that are twice as long. The minimum of the MIE and MIED for fast electrostatic spark discharges have been determined for five dust qualities.