Diaphragms are basic elements or components for the measurement of pressure. They transform pressure into linear travel. Two diaphragms combined make a "Capsule" capable of measuring absolute or differential pressure. Diaphragms are also used as separator between medium and sensor element.

Travel

Depending on hardness, thickness, shape of the material used, diaphragms change their height when under pressure and this change is reproducible. The distance by which the height changes is called "Travel". Depending on the application this travel may be taken up by a gauge movement, sender or switch. The travel of a diaphragm capsule can extend up to 5 millimetres or 0.2". lf this is not sufficient for a particular application two or more diaphragms may be stacked and their individual travels can be combined.

The standard diameters of Beck's diaphragms are between 10 and 155 mm. For further information please see the chart below.

Depending on the specific requirements, the travel of these diaphragms and capsules can be made linear or non-linear (e.g. for altitude measurements where the travel is linear in relation to the altitude and not in relation to the pressure). There is practically no hysteresis.

Material

The selection of suitable materials is extremely important and depends on the requirements with regard to corrosion resistance, temperature, elasticity, strength and hardness. Some of the materials Beck uses are: Copper Beryllium (CuBe2) and Duratherm which can be hardened, and Bronze, Nickel Silver, Stainless Steel (316 L , 316 Ti) and Hastelloy C which cannot be hardened.