a standard, model, or pattern. 2. general level or average: Two cars per family is the norm in most suburban communities. 3. Education. a designated standard of average performance of people of a given age, background, etc. a standard based on the past average performance of a given individual.
For example, pressure regulators are used in gas grills to regulate propane, in home heating furnaces to regulate natural gases, in medical and dental equipment to regulate oxygen and anesthesia gases, in pneumatic automation systems to regulate compressed air, in engines to regulate fuel and in fuel cells to regulate hydrogen.
This means that a single-stage regulator has to be adjusted to maintain a constant pressure as thegas in the cylinder is used, but a two-stage regulator does not. Two-stage regulators are typically used when more stability of operation is required and are often used in specialty gas applications, like gas chromatography.