| 摘要 |
913,473. Electrolytic testing apparatus. HERSCH, P. March 1, 1961 [March 7, 1960], No. 8017/60. Class 37. A galvanic cell for the estimation of oxygen in a gas includes a porous cathode of which a portion is exposed to the gas, and of material not attackable by the gas and the electrolyte, an anode incapable of evolving hydrogen upon being circuited with the cathode, a porous diaphragm separating and contacting the anode and cathode and possessing greater electrolyteretaining power than the cathode, and a volume of electrolyte insufficient to fill the combined pore volume of the assembly. An anode of porous nickel sintered on to a nickel grid and impregnated with cadmium is sandwiched between two layers of porous plastic sheet which contain caustic potash solution and are covered by porous silver layers. Other embodiments include a stainless steel rod plated with antimony as anode, covered successively by porous plastic and a porous copper cathode; and a five-layer structure having two cathodes and a common anode. The gas to be tested should be pre-humidified, and the amount of electrolyte in the cell can be adjusted either by submersion of the assembly in electrolyte and subsequent pressing between absorbent paper, or by use of a syringe. Other specified cell materials are:- cathode-graphite, metal-activated carbon or nickel, and porous plastic with platinum, gold, or silver deposited in its pores; anode-lead, bismuth, steel coated with arsenic, and nickel or carbon impregnated with cadmium, lead, antimony, or ferrous hydrate; diaphragmporous polyvinylchloride or magnesium oxide; electrolyte-potassium bicarbonate and sulphuric acid. The cell current depends, at low flow rates, on the rate of supply of oxygen (coulometric operation) but at high flow rates on the oxygen concentration only. A limited sample may be analysed by enclosing it in the cell housing, or injecting it into a flowing carrier gas, and integrating the resultant current. Oxygen in a liquid or solid may be measured subsequent to transfer to a carrier gas, and the apparatus may be employed to give warning of air leaks, and for measurements related to blood, boiler feed water, the decomposition of peroxides, and the polymerization of ethylene. Specifications 707,323 and 750,254 are referred to.
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