高效过滤器钠焰效率试验中NaCl浓度对测量精度的影响

在核级高效过滤器钠焰效率试验中，使用自制的稀释装置和研制的钠焰光度计，试验测量了NaCl浓度在4 ng/m³～13 mg/m³范围内，气溶胶燃烧光强与浓度之间的关系，然后用最小二乘法对测量值进行曲线拟合。研究结果表明：低浓度区，光电流与NaCl浓度间为线性关系，光谱的自吸收系数为1；中、高浓度区，光电流与NaCl浓度间不再符合线性关系，光谱的自吸收系数随浓度的增加而减小。研究结果要求：在高效过滤器效率测量时，如果使用国标的效率计算公式，须保证NaCl的原始浓度低于0.05 mg/m³；如果原始浓度高于0.05 mg/m³，则需使用实际标定的光电流与NaCl浓度间的关系曲线来代替国标的效率计算公式。

Influence of NaCl Mass Concentration for Mesurement Precision in Sodium Flame Efficiency Test of HEPA Filter

The relationship between NaCl concentration and light intensity of burning NaCl aerosol in the range of 4 ng/m³-13 mg/m³ during the sodium flame efficiency test of HEPA filter was studied, the experimental data were analyzed by the least square method. The result shows that there is a linear relationship between photo current and NaCl concentration in the range of low concentration, and the self adsorption coefficient of NaCl light spectrum is 1. However, there is no linear relationship in the range of middle and high NaCl concentrations while the higher the concentration, the less the linear relation, and the smaller the self adsorption coefficient. In a word, for HEPA filter test, the efficiency calculation equation of the national standard can be used when the NaCl concentration is lower than 0.05 mg/m³, or the new relation curve should be adopted through calibrating the photo current of sodium flame photometer for different NaCl concentrations.