A Sun valve, (aka Solventil, solar valve) is a form of flow control valve, notable because it earned its inventor, Gustaf Dalén the Nobel prize in physics. A flow control valve regulates the flow or pressure of a fluid. ... Nils Gustaf Dalén (November 30, 1869 – December 9, 1937) was a Swedish Nobel Laureate and industrialist, the founder of AGA, the company and inventor of the AGA cooker and the Dalen light. ... Hannes Alfvén (1908–1995) accepting the Nobel Prize for his work on magnetohydrodynamics [1]. List of Nobel Prize laureates in Physics from 1901 to the present day. ...

The valve formed part of the Dalen Light which was used in lighthouses from the 1900s through to the 1960s by which time electric lighting came to dominate. A Dalen Light was the predominant form of light source in lighthouses from the 1900s through to the 1960s by which time electric lighting would come to dominate. ... The Peggys Point lighthouse in Nova Scotia, Canada An aid for navigation and pilotage at sea, a lighthouse is a tower building or framework sending out light from a system of lamps and lenses or, in older times, from a fire. ...

The valve is controlled by four metal rods enclosed in a glass tube. One rod is blackened, while the others are highly polished. As daylight made the rocks visable, the heat of the sun allowed the expanding dark rod to cut the gas supply.

References and further reading

http://www.aga.com/web/web2000/com/WPPcom.nsf/pages/History_SunValve