Diaphragm pressure gauges consist of a diaphragm seal assembly coupled with a standard pressure gauge, connected via flange, thread, or nut; they measure pressure by diaphragm deformation, which transmits force through an inert fill fluid (e.g., silicone oil or glycerin) to a Bourdon tube for indication—ideal for highly corrosive, high-temperature, viscous, or crystallizing media in petrochemical, pharmaceutical, food, and alkali production. The diaphragm is made of corrosion-resistant materials like stainless steel or Hastelloy, isolating the sensing element from the process medium; temperature-induced error is typically ≤0.1%/°C, with measurement ranges from 0.1 to 100 MPa, accuracy classes of 1.6 or 2.5, and operating temperatures from –20 °C to +55 °C.