The Viking Model C-2 Thermostatic Release is a corrosion resistant rate-of-rise releasing device for use on hydraulic and pneumatic release systems controlling operation of Viking deluge valves on deluge or preaction systems. When subjected to a temperature rise greater than 15° (8.3 °C) per minute, the Model C-2 Thermostatic Release opens to allow pressure in the release system to escape. The operating principle is based on metals expanding at unequal rates. The unit may also be equipped with a fixed temperature release that will release the system at a preset temperature regardless of the rate of temperature increase. The Model C-2 Thermostatic Release, Nitrogen is designed for use outdoors or in open structures where sea water atmospheres are present. It may be used on either pneumatic release systems.