8. Manufacturing and installation constraints

8.1 General notes on the construction of primary elements

When it comes to diaphragms, the standardizer's concern [2] is obviously to specify a component that is deemed reliable because it can be easily produced in a reproducible way. The plate must be rigid but thin. The orifice is a simple, cylindrical, centered hole with a rough machined upstream edge. When pressure constraints dictate that the plate thickness exceeds 2% of the pipe diameter, a chamfer at a fixed angle of 45 is made on the downstream side (figure 3 a). Checks on flatness and surface finish are carried out with the naked eye.

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