Which of the following is NOT an example of an overpressure protection device?

The correct response identifies the pressure indicator gauge as the option that is not an example of an overpressure protection device. Overpressure protection devices are specifically designed to prevent pressure from exceeding safe limits within systems, ensuring that they operate within safe parameters.

A pressure indicator gauge serves a different purpose; it is used to measure and display the pressure within a system, providing valuable information for operators but not actively engaging in pressure management or safety measures. It simply informs users about the current pressure level without taking action to relieve pressure or shut off flow in case of an overpressure situation.

In contrast, devices like monitor regulators, pressure relief valves, and automatic shutoff devices are designed to respond to pressure changes. Monitor regulators help maintain pressure at set levels; pressure relief valves open to release excess pressure when necessary, and automatic shutoff devices can close off systems when excessive pressure is detected. Thus, while the other options play a critical role in protecting systems from overpressure, the pressure indicator gauge does not contribute to safety through active pressure regulation.