A burst temperature indicator system for determining when an electrical contact or other component reaches a predetermined temperature. In operation, a trace material may disperse into a surrounding environment, and be detected, when the electrical component reaches a predetermined threshold temperature. One or more foil barriers may be ruptured or broken by temperature-induced gas pressure. According to another aspect of this disclosure, a rupture disk may be burst at a predetermined temperature to generate, or enable emission of, a light signal. According to another aspect, a rupture disk device acts as, or is associated with, an engine to drive one or more electro-mechanical and/or acoustic devices to signal the occurrence of a predetermined temperature.

A temperature sensor for measuring a temperature within a subsea installation includes a fixture portion coupled to the subsea installation and a retrievable portion that is selectively operable to couple to the fixture portion. The fixture portion includes a constant volume of a fluid disposed at a measurement point within the subsea installation. The retrievable portion includes a pressure sensing element operable to measure a pressure associated with the constant volume of fluid such that a temperature at the measurement point is determinable.