Instrument for Continuous Measurement of Low Concentrations of Oxygen in Gases

Abstract

VOLUME19, NO. 11 10 cm. of mercury with 5% ethanol-95% argon mixture. The threshold was at 950 volts and the plateau was flat, =*= 1 %, for 350 volts when the tube was used with a modified Neher-Pickering type of quenching circuit. The cathode of the tube w*as cleaned in concentrated nitric acid, thoroughly washed in distilled water, dried, and oxidized in a large flame before assembly.

The hydrogenation of fatty oils with palladium catalyst. IV. Pilot‐plant preparation of shortening stocks

“…After charging with oil and catalyst the reactor was twice evacuated and twice filled with nitrogen. The oxygen level, as determined by a Deoxo indicator (4), was then about 0.15 to 0.20%. The nitrogen was replaced by hydrogen; and heating, stirring, and circulation of oil with catalyst were started.…”

Gas Analysis

“…A classical determination of low concentrations of oxygen in streaming gases is based on measurement of the temperature rise produced when the gas, mixed with hydrogen, is passed over a combustion catalyst. If a thermocouple is used-the cold junction upstream, and the hot junction downstream, from the catalyst-an instrument largely independent of changes in the ambient temperature, and capable of continuously recording oxygen concentrations as low as 2 p.p.m., may be constructed (59). Instead of measuring the temperature rise accompanying the combustion, the water so formed may be taken as a measure of the oxygen content of the original gas.…”

“…Hydrogen. Traces of hydrogen (in the presence of excess oxygen) are determinable from the temperature rise produced when the gas mixture is passed over a catalyst-for example (59). Other combustibles should be absent, or the conditions must be arranged so that only hydrogen burns.…”

Automatic Operations in Quantitative Analysis

“…Here, Wheatstone bridge circuits in conjunction with recording potentiometers are invariably included (125, 147, 322, 347, 351, 354, 359, 362). When oxygen or excess air is the desired constituent, in an atmosphere not containing oxidizable fuels, sufficient amounts of standard fuels are added (20,23,101,179,322,363,404,495) to consume all the oxygen present, thus giving a measure of the concentration according to the heat evolved. Many commercial instruments, some of them portable, based on both principles of temperature measurement for use as safety devices in mines, fuel tanks, and tunnels, are on the market (20,58,70,319).…”