Abstract: An optical gas densitometer is provided comprising a conical filter portion having a front and rear end disposed to the inside of a cell portion and formed into a conical shape, which has a reflection mirror disposed to the inside of the front end thereof, windows disposed at the rear end thereof and in which the angle between an incident optical beam and an exiting optical beam is predetermined. Plate means at the front end of the filter and formed in a space between the inside of the cell portion and the outside of the conical filter portion, divides the space into a gas feed channel below the plate means and a gas exhaust channel above the plate means. An opening channel is disposed between the gas feed channel and the gas exhaust channel towards the rear end of the filter. A partition plate connected to the plate means at the front end of the filter, divides a gas sampling tube into first and second channels which correspond to the feed channel and exhausting channel, respectively.

Abstract: A heat exchanger fin according to the invention has a multiplicity of fins arranged substantially in parallel with the direction of air flow and at least one heat transfer tube to which said fins are connected in a heat conducting relation. A multiplicity of louvers inclined by a small angle to the direction of air flow are formed in said fins.According to this construction, it is possible that the air as a whole can flow substantially straight across the heat exchanger and can strongly collide with all louvers, thereby to ensure a reduced flow resistance encountered by the air flow, as well as improved heat transfer performance of the heat exchanger.

Abstract: A fin assembly for heat exchangers used in air conditioners or the like. The fin assembly is formed from a thin plate material which is bent and wound to have a plurality of alternating turns each of which constitutes a fin. The fin is provided with a multiplicity of louvers cut-out and raised from the major plane thereof. The fins are inclined at an angle .theta. which is 30.degree. or smaller to the direction of flow of the gas entering the fin assembly, while the louvers are inclined at an angle .gamma. which is 20.degree. or smaller to the direction of flow of the gas entering the fin assembly in the direction opposite to the direction of inclination of the fin plates.

Abstract: An ammonia gas analyzer and a sulfuric acid converter utilized in the ammonia gas analyzer in which a sample gas is maintained at a relatively high temperature prior to entering the sulfuric acid converter to thereby prevent acidic sulfuric acid sulfates and/or ammonia sulfates from crystallizing and being deposited on the walls of the device. The ammonia gas analyzer includes gas sampling means, a gas measuring channel connected to the gas sampling means, a comparison gas channel connected parallel to the measuring gas channel with the measuring gas channel including an NH.sub.3 /NO converter for converting NH.sub.3 in a sample gas into NO and means for measuring a concentration of NH.sub.3 on the basis of variations of an amount of NO in the measuring gas channel with respect to that in the comparison gas channel.

Abstract: An oxygen gas analyzing device in which gas sampled from a flue is analyzed without the need of an external driving source. A sampling tube protrudes into a flue through a wall thereof. A partition board divides the gas sampling tube extending from the protruding end of the tube forming gas flow-in and flow-out paths. A solid electrolytic element is positioned in a ceramic tube having one end open to the outer end of the gas sampling tube. A heater is provided in the walls of the ceramic tube.

Abstract: A method of producing a heat exchanger in which a fin block of porous metal and fin plates connected to the fin block are unitarily secured to a serpentine heat-transmitting pipe. A plurality of fin molds produced with the use of plastic patterns formed therein with continuous, three-dimensional cavities are assembled with the heat-transmitting pipe shaped beforehand into a serpentine form in such a manner that the fin molds enclose the heat-transmitting pipe with suitable spacing intervals defined between the fin molds themselves and between the fin molds and the heat-transmitting pipe. Molten metal of high thermal conductivity is cast into continuous cavities in the fin molds and into the spacing intervals, and the material of the fin molds is removed after the molten metal has solidified.

Abstract: A programmable logic array (PLA) is achieved by taking various EOR sums of programmable AND term generator output signals. The EOR term generator receives externally applied logic constant signals on respective logic constant signal lines. Each logic constant signal line is coupled to the AND term generator outputs by a plurality of EOR elements which are either connected in series and controlled by different AND terms or cascaded in tree-like fashion.

Abstract: A three-dimensional network porous metallic structure is formed by filling the internal cavity of a mold, which has been prepared by making use of a three-dimensional network resin pattern, through driving the molten metal into the cavity by a pressure or through sucking the molten metal into the cavity by reducing the pressure in the cavity. The porous metallic structure thus obtained is characterized by a large specific surface area, as well as a reduced pressure drop of fluid passing through this structure, and, therefore, is fit for various uses such as the material of fins of heat exchangers, various filters and so forth.