Final answer:
A flame safety or flame supervision device, such as a flame sensor, is built to shut down the burner system in case of ignition or combustion failure, preventing unburnt fuel accumulation and ensuring safety.
Step-by-step explanation:
The device designed to shut down the burner system if there is a failure of ignition or combustion is commonly referred to as a flame safety or flame supervision device. Its purpose is to cut off the fuel supply, thereby preventing the accumulation of unburnt fuel and reducing the risk of explosion or fire. One example of such a device is the flame sensor, which detects whether a flame is present. If the sensor does not detect a flame, it communicates with the control system to shut off the fuel supply. This is an essential safety feature in modern heating systems, serving to protect both the equipment and the users from potential hazards.