ABSTRACT
In the design of an elastic element such as a diaphragm the actual stresses establish the range and the accuracy of the element; therefore, they must be precise. The sensitivity of a diaphragm will increase with temperature as the modulus of elasticity decreases. Material must be able to withstand the corrosive effects of the environment for the life of the instrument at all temperatures. For repeated or cyclical loading, endurance or fatigue strength of the material is the criterion. Machinability, formability, and weldability are important criteria in material selection. For every application there is a cost beyond which one cannot venture and which therefore proscribes the limit that can be paid for a material to meet the application requirements. Materials which can withstand fatigue and corrosive elements will obviously prolong service life. Specifications may dictate that the material be selected to meet requirements such as humidity, salt spray, fungus growth, Chemicals, and temperature extremes.
