Which of the following is NOT a common type of pressure regulator?

Cable-operated type is not a common type of pressure regulator used in typical applications. Pressure regulators are devices that control the pressure of a fluid or gas, ensuring that it remains at a set level for proper operation. The common types of pressure regulators include diaphragm, lever, and spring types, each of which utilizes well-established mechanical principles to maintain consistent pressure.

The diaphragm type employs a flexible membrane to respond to pressure changes and regulate gas flow. The lever type often uses a lever mechanism to balance forces and adjust pressure based on operational needs. The spring type relies on spring tension to control pressure levels, compressing and expanding to regulate gas flow effectively. While cable-operated mechanisms are utilized in other contexts or specialized applications, they do not have the same prevalence or conventional use as the listed types when it comes to standard pressure regulation systems.