Selection of diaphragm material for pressure transmitters

It is recommended to use 316 gold-plated. This operating condition is quite typical in hydrogenation units. Under normal conditions, in a hydrogen environment, the material only needs to meet the Nelson curve requirements, but the Nelson curve is applicable to the materials of pipes or equipment. Although austenitic stainless steels can be used in hydrogen-containing environments, since grade 316 still contains a small amount of carbon, and given the very high hydrogen partial pressure in the conditions described by the questioner, the small amounts of iron carbide present in the 316 diaphragm will more or less be reduced to Fe + H4C by hydrogen. Due to the thinness of the diaphragm, this will over time lead to irregular deformation of the diaphragm, thereby affecting the accuracy of measurements. The diaphragm of ordinary transmitters is very small, and gold plating is not expensive; generally, it adds a cost of 1,000 yuan. So the poster should use a gold-plated diaphragm.