The paper reports the demonstration of linear and similar responses of a Ratfisch RS-55CA flame ionization detector (FID) to a solvent mixture identical to the volatile organic compounds (VOCs) in the coating and catalyst (NSN 8010-01-336-3036) and to the calibrating gas (propane) used in field calibrations of the FID. Sensitivity and linearity have been shown to extend from 715 to 45 mg/cu m, which brackets the calculated short-term exposure limit (STEL) and lower action thresholds. Monitoring is maintained constantly and, under field conditions, equilibration occurs rapidly (analysis and output transpire in milliseconds). As a trigger for fail-safe conversion from recirculation mode to a straight-through paint spray booth configuration, the FID may confidently be expected to initiate a corrective response before a transient elevation of VOC concentrations overexposes area personnel.