Principle The diaphragm valves are used specifically in the dust collector system. The valve consists of 2 air chambers divided by a piece of diaphragm. The 2 chambers are connected through an air passage (air passage's diameter is smaller than the orifice of the pilot valve). When the orifice opens, the air in the upper chamber is exhausted much faster than the speed of air that enters through the air passage. The air pressure of the upper chamber drops significantly, the higher pressure of the lower chamber pushes the diaphragm up and opens a bigger passage for air to enter into the bottom chamber. This sudden burst of air is used to inflate the fabric filter so as to shake off all the dust clinging on the bag filter. When the orifice closes, the pressure in both chambers equalizes and the diaphragm returns to its original position via the force of the coiled spring.