Abstract: For continuous measurement of the air permeability of a moving or stationary cloth web, the latter is guided over a measuring orifice which opens at the end of a measuring tube through a convexly curved outer surface of a measuring head. This convexly curved surface deflects the web. As a result of the tensile stress in the web, the web thereby automatically sealingly clings to this surface around the measuring orifice. In the measuring tube, air is sucked by a pump through the web part extending across the measuring orifice. The flow speed of the air sucked through a test sample is measured in a flowmeter, is indicated as the air permeability of the test sample by an indicator instrument, and if appropriate is used for regulation.

Abstract: A pyroelectric or ferroelectric sensing element consists of a substrate with a thin layer of sodium nitrite. Electrodes may be applied to both sides of the sodium nitrite layer, or, alternatively, only one electrode may be used. In one embodiment, an array of electrodes is applied to one side of a continuous sodium nitrite layer, while the other side has a continuous electrode. In another embodiment, the sodium nitrite layer consists of separate portions, each interposed between one electrode of an electrode array and either the substrate or a second, continuous electrode.

Abstract: Sodium nitrite in liquid form is deposited on a substrate and allowed to crystallize thereby forming a thin layer on the substrate. The substrate is either dipped into a solution containing sodium nitrite or into sodium nitrite in the molten state and then pulled out again. Subsequent drying or cooling of the wetted substrate top surface causes the crystalline film to form. Alternatively, sodium nitrite in a liquid state is applied to the top surface of the substrate and the substrate is rotated to assure an even distribution of the sodium nitrite. Again, drying or cooling causes the crystalline layer to form. The so manufactured unit is shown as part of a pyroelectric radiation detector, as image receiver in a television camera tube and as the storage element in a field effect transistor arrangement.