§ 86.327-79 - Quench checks; NOXanalyzer.

(a) Perform the reaction chamber quench check for each model of high vacuum reaction chamber analyzer prior to initial use.

(b) Perform the reaction chamber quench check for each new analyzer that has an ambient pressure or “soft vacuum” reaction chamber prior to initial use. Additionally, perform this check prior to reusing an analyzer of this type any time any repairs could potentially alter any flow rate into the reaction chamber. This includes, but is not limited to, sample capillary, ozone capillary, and if used, dilution capillary.

(c) Quench check as follows:

(1) Calibrate the NOX analyzer on the lowest range that will be used for testing.

(2) Introduce a mixture of CO2 calibration gas and NOX calibration gas to the CL analyzer. Dynamic blending may be used to provide this mixture. Dynamic blending may be accomplished by analyzing the CO2 in the mixture. The change in the CO2 value due to blending may then be used to determine the true concentration of the NOX in the mixture. The CO2 concentration of the mixture shall be approximately equal to the highest concentration experienced during testing. Record the response.

(3) Recheck the calibration. If it has changed more than ±1 percent of full scale, recalibrate and repeat the quench check.

(4) Prior to testing, the difference between the calculated NOX response and the response of NOX in the presence of CO2 (step 2) must not be greater than 3.0 percent of full-scale. The calculated NOX response is based on the calibration performed in step (1).