For probe lining of either borosilicate or quartz glass, probe liners are used for stack temperatures up to approximately 900 ° F (482 ° C); quartz liners are used for temperatures between 900 and 1650 ° F (482 and 899 ° C). Although borosilicate or quartz glass probe linings are generally recommended, 316 stainless steel, Incoloy, or other corrosion-resistant metal may also be used.Isokinetic sampling requires the precise adjustment of the sampling rate with the aid of the pitot tube manometer readings and nomographs such as APTD-0576. 9 If the pressure drop across the filter in the sampling unit becomes too high, making isokinetic sampling difficult to maintain, the filter may be replaced in the midst of a sample run. To measure the concentration of particulate matter, the sampling time for each run should be at least 60 min, and the minimum volumetric rate of sampling should be 30 drySome commonly used components in stack-sampling systems are illustrated in Figure 8.3l. If ball-and-socket joints and compression fittings are used, any arrangement of components is readily set up for field use. The stack sampling components are selected on the basis of the source to be sampled, the substances involved, and the data needed. A summary of sampling procedure outlines was developed by industrial hygienists10 for specific substances.The procedural outlines serve as a starting point in assembling a stack sampling system, after consideration has been given to the complications that might arise because of the presence of interfering substances in the gas samples.