Process materials (gases and chemicals)

Which type of fitting, widely used in high-purity gas piping, seals by compressing a metal gasket between faces?

  1. APush-on rubber hose
  2. BThreaded fittings wrapped with tape
  3. CMetal-gasket face-seal fittings such as VCR
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Answer: C. Metal-gasket face-seal fittings such as VCR

High-purity gas piping uses fittings (such as VCR) that seal by clamping a metal gasket between faces. Because no rubber or sealing tape is used, permeation of moisture from outside, gas contamination and particle generation are suppressed, and high leak-tightness is achieved.

  • A. Rubber is permeable to moisture and can contaminate gas.
  • B. Sealing tape is a contamination source and is not used in high-purity lines.
  • C. Correct. It is a face-seal fitting with a metal gasket.
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