Arrangement for the accurate, preferably computer-controlled fluid-volume flow measurement within a wide volumetric flow range

摘要

The invention can be simplest described in exemplary fashion as a subassembly of a unit for measuring the flow behaviour of fittings (kv measuring unit). Here, the object is to accurately measure the volumetric air flow drawn in from the surroundings (the measuring space) as a function of the degree of opening. The proven differential pressure method is usually used as the measuring method. The fact that the volumetric flow changes within very wide limits during the measuring of a test piece is a handicap. Therefore the requisite measuring accuracy cannot be maintained without a special measure (use of a stop plug, etc.). In the measuring arrangement according to the invention working according to the differential pressure method, the choke cross-section is variable and is adapted in a computer-controlled manner to the changing conditions. In this way, the measuring operation can be optimised and the measuring uncertainty can also be reduced by repeated measuring with different choke cross-sections (gap widths). In contrast to conventional differential pressure devices, the arrangement according to the invention is especially suitable as a subassembly of a fully automatic, computer-controlled unit.