Abstract: The invention relates to dust/particle monitors, and particularly but not necessarily exclusively to a method of monitoring fine particles harmful to humans in working environments. Equipment and methods of detection are known but which have several disadvantages such as no instantaneous warnings of excessive exposure, bulky sampling equipment, prone to errors due to poor handling of particles, and fluctuating flow rates of air borne particles. The object of the invention is to provide a method and equipment that avoids those disadvantages mentioned above, an objective met by a method of monitoring dust/particulate material concentrations in air, comprising drawing air through a monitor at a predetermined rate to enable particles to pass through a measurement section one at a time, whereby they may be individually detected and counted.

Abstract: A bag expander for a flexible bag comprising a frame of two U-shaped rods or wires which are slidably connected so that the frame can be expanded when placed inside the bag mouth. Loops on the ends of each frame member slide on the limbs of the other frame member. U-shaped leg members of rod or wire are pivoted by the ends of the limbs to the bases of the frame members respectively so that the frame can be supported above ground. To slow the expander the frame members are telescoped together and the leg members are folded to lie side by side with the frame members.