An injector for use in injecting a fluid in a medical injection procedure includes a drive mechanism to pressurize the fluid; a sensor to measure a variable that is proportional to fluid pressure (that is, a direct or indirect measurement of fluid pressure); and a pressure monitor (for example, including hardwired circuitry and/or software) in communication with the sensor and the drive mechanism to stop the injection procedure when the sensor measures a value of the variable that corresponds to a pressure hazard limit. Preferably, the pressure monitor further limits power input to the drive mechanism to a power limit once the variable reaches a value that corresponds to a power limiting pressure that is below the pressure hazard limit.