The air operated double diaphragm pump is a type of positive displacement pump that draws fluid into the inlet side of one or more pistons, where it is compressed and pushed out through the outlet side. The inlet and outlet ports are separated by a diaphragm. As the diaphragm moves outward, it creates an area of low pressure on its outer side, drawing fluid into the pump chamber. As this area expands, so does its volume. The air operated double diaphragm pump uses compressed air to actuate these pistons.
The diaphragm seals against a surface called a sealing face or seat, which can be made from various materials including metal and plastic. The chamber wall may also be made from a variety of materials, but should be able to withstand high temperatures and pressures without becoming brittle over time.