Do you have any data on the weights of samples before and after oven drying? If you know how much solvent is going into the oven, and how long it is taking to flash off or boil away then you (or someone else) should be able to calculate the likely solvent loading and decide whether you need to add ventilation to the oven.... Plus, it depends on what the solvent is, and how long it takes to evaporate. What its flashpoint is, and how deeply it may be absorbed into the sample... A client was recently issued a material breach notice for failure to have a DSEAR assessment available for (amongst other things) an oven which was drying inks and paints from small components. Long story short - there was, and could never have been, any risk of significant fire or explosion in the oven (components introduced slowly on a conveyor, minute levels of solvent. forced air ventilation, system interlocks etc etc....).

Can you tell us what the solvents are and the temperature of the oven as well?