Cabinet X-ray Systems used in Food and Security Inspection are designed to comply with regulations around the world. While these regulations vary by country, we find that most systems have no measurable emissions if the x-ray curtains are in an undisturbed state.
There are many design features which can help address how to minimize emissions when product is passing through the system. Here we will focus on just one of these features, layering curtains.
Most x-ray systems will have curtains at either two or three locations on both the in-feed and the exit of the x-ray tunnel which the product is conveyed through. The reason these curtains are spaced apart is so that if a product displaces or lifts up one curtain set, the curtain in front or behind it should block any scattered x-rays.
Today many food scanners utilize 0.25 or 0.35 mm Pb equivalent curtains to block emissions. What many people do not realize is that the prime source of emission is actually through the slit between the flaps of a single x-ray curtain. So regardless of the protection level, if there is a gap between the flaps as they sway or are knocked about, emissions will increase.
The best approach is actually to layer two lighter sets of curtains so the flaps are offset. For instance, two 0.125 mm Pb equivalent curtain can be cut with 1” wide flaps, where the flaps are offset ½” on each panel. When these panels are installed back-to-back, they provide full protection even if there is a gap between some of the flaps.
Not only will emissions be reduced, but if lightweight curtains are used, you may experience fewer problems with lightweight product flow since two layers of our 0.125 mm Pb curtains are lighter than a single layer of typical 0.25 mm Pb vinyl.