NITROGEN OXIDE MEASURING APPARATUS

摘要

PROBLEM TO BE SOLVED: To enable measurement of oxide by a method wherein oxygen of a gas to be measured undergoes a pumping treatment by a main pump means to adjust the concentration thereof and another pumping treatment is performed based on an interelectrode voltage by a measuring pumping means to detect a pump current corresponding to the amount of the oxygen. SOLUTION: A gas to be measured is introduced into a first chamber 54 through a diffusion speed control section 58 to control the partial pressure of the oxygen in the first chamber 54 controlled to a specified value by a main pump cell 68 and the atmosphere of the first chamber 56 is introduced into a second chamber 5 through a diffusion speed control section 60 to analyze nitrogen oxide. The oxygen then generated is drawn by a measuring pump cell 84 and an ammeter 88 detects a pump current Ip2 flowing with the action of the cell 84 to d measure the amount of the nitrogen oxide in the gas to be measured. An internal pump electrode 64 and a measuring electrode 72 in the first chamber 54 are built up with a cermet electrode containing 0.01-1% of gold and the balance of an alloy mainly composed of a platinum family element. Thus, a low activity as decomposition catalyst of the nitrogen oxide in the method eliminates possible decomposition of the nitrogen oxide under a low partial pressure of the oxygen thereby enabling highly accurate measurement of the nitrogen oxide.