Abstract: A fluid flow machine has a diaphragm pump which is driven by an electromagnet and is confined in a pressure-resistant capsule together with the electromagnet as well as with the electronic control unit for the electromagnet. The constituents of the capsule are connected to each other so that they form one or more gaps each having a configuration and dimensions such as to prevent the propagation of flames and/or sparks from the interior of the capsule to the surrounding area. This renders it possible to use the machine in an explosive atmosphere, even if the pump is designed to deliver metered quantities of flammable fluids. A gap of the above outlined character is provided between two portions of the capsule where a reciprocable plunger extends toward the diaphragm.

Abstract: A diaphragm pump, particularly for conveying flammable media, has a housing whose interior is divided into a pumping chamber and a second chamber by a deformable diaphragm having a marginal portion which is clamped between two sections of the pump head and being deformable by a cupped member which is biased in one direction by a coil spring and is movable in the other direction by a plunger receiving motion from a motor and being in mere abutment with the bottom wall of the cupped member. The housing defines a first set of gaps which connect the second chamber with the atmosphere and a second set of gaps which connect the atmosphere with the pumping chamber. The dimensions and shapes of the gaps are such that they do not permit the propagation of ignition from the respective chamber to the atmosphere.