Once the minimum ventilation requirement is known, dampers must be secured so that ventilation is never reduced below the minimum. The best method is to cut away the damper so that it is not possible under any condition to reduce the ventilation rate to an unsafe level. Manually adjusted stops, and sometimes even welded stops, have been found to be insufficient to prevent accidental loss of ventilation due to incorrect damper settings.
According to NFPA-86, additional Solvent Vapor Analyzers can be installed onto a process to specifically control damper positions. By adding additional LFL Analyzers to safely automate the dampers, the amount of ventilation air needed to maintain a safe LFL level in an oven would be minimized. Precise measurement of solvent vapor concentrations should be made with the highest level of accuracy to optimize the control of damper position and achieve the highest degree of safety while maximizing energy savings.
The measuring principle of the sensor is important to achieve these goals. The more solvents that are contained in the process, the greater the error and the wider the damper will stay open, unless precise measurement is continuously taken.