Sorry but the Bourdon Tube is a flattened oval the length and diameter is determined by the task they are to perform. They use air and may be sealed or open at one end. The are the measuring device used in vacuum and pressure gauges that use a pointer that moves over a graduated dial. The device you are talking about is a capillary tube filled with mercury vapor and always sealed. They are 1/8th inch in diameter or less and their length is determined by their application can be two inches to many feet long. They are widely used for expansion valves and cold controls in refrigeration and water based heating systems. Unlike the Bourdon Tube, their operation range is quit narrow and is fixed at the time of manufacture. Marshall On Mon, 19 Jan 2009 10:11:31 -0800 "Bob Jasinski" <rpjasin@xxxxxxxxxxx> writes: > Lindsey, > > The bourdon tube is a sealed tube about 1/8" thick and is installed > in the > air stream path. It is filled with a gas (probably air I'm not > sure) that > applies pressure to a bellows that opens and closes the heater > control valve > like a thermostat in your home. It is designed to maintain a > constant > temperature within the car's interior based on what the driver sets > it at. > The heater control valve without the tube just maintains a fixed > amount of > coolant flow through the heater core, it is not regulated > automatically, > only by the fixed setting via the temp control handle. > > Bob J > ------------------------------------ To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm For archives go to http://www.forwardlook.net/300-archive/Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/Chrysler300/join (Yahoo! ID required) <*> To change settings via email: mailto:Chrysler300-digest@xxxxxxxxxxxxxxx mailto:Chrysler300-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: Chrysler300-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/