1. Is recirculating solvent fumes dangerous?
Recirculating solvent fumes is perfectly safe if designed and maintained correctly.
The solvent fumes are recirculated under carefully controlled conditions by the Optima controls with various safety functions. Each circuit of recirculation has a gas monitor to measure the solvent concentration as %LEL and this becomes the control point for the air recirculation. When the solvent levels are low, the recirculation is fully open reducing the exhaust to a minimum. However, as solvent levels increase then the recirculation damper will modulate increasing the exhaust and drawing in air make-up to dilute the solvent concentration and maintain constant safe levels.
An Optima control panel by EPM on a flexo press
The gas monitors incorporate various alarm safety functions should the solvent concentrations increase. First, it will close the recirculation totally with an audible/visual alarm and then shutdown the machine if levels continue to rise.
Additionally, depending on the dryers we can install flame arrestors which prevent a flash-back from a gas burner should the concentration get to an explosive condition.
Since the gas monitors are essential safety devices, they must be kept regularly calibrated every 3-6 months depending on the type. EPM Maintenance offer a planned calibration service and carry extensive spares. At the same time, we check the operation of all the alarm functions to ensure continuing safe operation.
If you would like to discuss any aspect of the information outlined in this question, please contact EPM at firstname.lastname@example.org.