Sulfur fpd flow optimization and response normalization with a variable exponential function device

This paper describes the optimum flow characteristics of the flame photometric sulfur detector to maximize both the relative sensitivity and the exponential proportionality factor (“n”). In this investigation it was found that the gas flow rates for hydrogen and nitrogen plus oxidant as well as the oxidant to fuel ratio drastically affect both the exponential proportionality factor and the relative sensitivity. To accurately adjust all flame flow parameters, it is recommended that an oxygen, hydrogen, nitrogen system be used in place of the standard air, oxygen, hydrogen, nitrogen system. This paper also describes a simple, inexpensive electronic device designed to monitor the output signal of a flame photometric sulfur detector. With this device it is possible to obtain a linear response with changing sulfur concentration even in cases where the photomultiplier output current is proportional to the sulfur concentration raised to a power of less than two.