Method and apparatus for detecting the presence of powdered material in envelopes

The present invention relates to a method and apparatus for detecting the presence of powdered materials in closed envelopes, in particular, for detecting powdered infectious, contagious, contaminating, or other undesired substances that can be sent via mail. An apparatus for detecting the presence of powdered materials in envelopes comprises a container with an envelope-positioning unit, envelope corner or edge cutter, a powder excitation and extracting means for shaking the contents of the envelope, and a powder detector with a particle intake device, and air circulation system for circulation of the particle-containing air through the powder detector. The detector can be placed inside or outside of the sealed container and is connected to the cutting zone via the particle suction device. In operation, the envelope is placed into the envelope-positioning unit. Either a corner or an edge of the envelope is cut off or perforated so as to allow a part of the powdered material to leave the envelope while maintaining the other contents, except for small particulates, intact and inside the envelope. The envelope is then subjected to vibration or impacts under the effect of the excitation means. In case of detection of a hazardous material, the apparatus will produce alarm signals and will lock the door to restrict access to the apparatus.