Embodiments include eyewash valves in which the temperature of the water emerging from the valve is thermostatically controlled by a wax motor which regulates the flow of hot and cold water through the valve. Embodiments include provisions for continuing water flow through the valve despite failure of the hot water supply. Embodiments also include provisions for water flow through the valve despite failure of the wax motor in the upper position or in the lower position.

A chemo-mechano-chemical (C.sub.1-M-C.sub.2) system includes a base supporting an actuatable structure, said structure comprising a functionalized portion and being embedded in an environmentally responsive gel capable of volume change in response to an environmental stimulus; a first fluid layer disposed over the base and in contact with the actuatable structure, said first fluid layer comprising the environmentally responsive gel; and a second fluid layer in contact with the actuatable structure, wherein the layers are positioned such that the functionalized portion is in contact with the second layer in a first relaxed state and in contact with the first layer in a second actuated state and wherein the functionalized portion interacts with at least one of the layers to provide a chemical or physical response.

A thermostat having a hollow body, wherein the hollow body is at least partly filled with a thermosensitive medium. A heating element is provided for heating the thermosensitive medium. The heating element is located outside of the hollow body and is at least partially insulated electrically from the hollow body. The element is connected to the hollow body in a thermally conductive manner.

A thermostat comprises a hollow body containing a thermally responsive material, and a force transmitting member affixed to the body by an over-moulded portion.