Abstract: A compact compressor is provided which can be used for production of very high-pressure end products using a multi-stage compression process. In one exemplary application, the compressor can be used for each stage of the multi-stage compression process used in production of compressed natural gas (CNG), in which low-pressure natural gas (NG) is compressed to less than 1 percent of its volume at standard atmospheric pressure (e.g., to 2,900-3,600 psi or 20-25 MPa). The compressor includes spark-avoidance, heat-mitigation and oil separation systems to safely and effectively produce CNG from NG.

Abstract: In a method for extruding an aluminum slat for a roller shutter with an undercut slot extending along one edge of the slat and formed by spaced apart front and rear members extending from the body of the slat, breakage of the part of the extrusion die which forms the slot is prevented by forming the slot in two steps. In the first step, the slat is extruded through a die which forms the front member in a position angled outwardly, so that the portion of the extruding die corresponding to the opening of the undercut slot can be made thick enough to withstand the extruding pressure without breaking. The front member is then bent back by a rolling operation to its desired position relative to the rear member.