A flow impedance device is provided for an obstruction flowmeter for determining the flow rate of a compressible or incompressible fluid in a conduit. The flowmeter preferably includes means for measuring the temperature and pressure of the fluid as well as the pressure differential across the flow impedance device along with further means for computing a flow rate from the measured pressures. The flow impedance device may include a plate having a plurality of elongated openings arranged in a predetermined pattern. The plate is installed generally transverse to fluid flow in the conduit to force the fluid to flow through the plurality of elongated openings.
