The Locomotive . s, completely filled withwater. As heat is imparted by the furnace the hot water tends to rise, causing cir-culation throughthe radiators andback to the the systemnot be filled com-pletely it is evi-dent that circula-tion would avoid this con-tingency thesesystems are pro-vided with an ex-pansion tank, lo-cated above thelevel of the high-est radiator andconnected to theheater by meansof a riser or ex-pansion pipe. This acts as a water column to give a static head orpressure to the system. When water stands in the tank the boileroperator knows that the sys
The Locomotive . s, completely filled withwater. As heat is imparted by the furnace the hot water tends to rise, causing cir-culation throughthe radiators andback to the the systemnot be filled com-pletely it is evi-dent that circula-tion would avoid this con-tingency thesesystems are pro-vided with an ex-pansion tank, lo-cated above thelevel of the high-est radiator andconnected to theheater by meansof a riser or ex-pansion pipe. This acts as a water column to give a static head orpressure to the system. When water stands in the tank the boileroperator knows that the system is completely full, assuming, of course,all air to have been ejected. Either an altitude gauge or a return pipe from the expansion tankis provided to tell the level of the water. In case a pipe is used itis run down to the boiler room where, by opening a cock, the operatorlearns whether or not water stands to the required level. It is well,when this tank is located in an unheated part of the house, to provide. ^928^ THE LOCOMOTIVE 45 connections to both supply and return mains so as to insure circula-tion sufficient to prevent freezing. The riser mentioned above may beconsidered the connection to the supply line. It should be taken fromthe main supply line as near the boiler as possible so that air bubbles,liberated when fresh water is fed into the boiler, may rise to the ex-pansion tank instead of going through the system and becoming trappedin the radiators. Means of Pressure Relief Necessary Inasmuch as water expands considerably under heat the systemmust be provided with some means to take care of its increase involume. Frequently this is accomplished by running an open pipe fromthe top of the tank to the roof of the house, or back to the basementwhere it discharges into a drain. In the system mentioned in the firstparagraph the relief pipe to the roof where it was exposed tothe cold. Vapor passing up through it gradually froze and formeda plug which closed the pi
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Keywords: ., bookauthorhartfordsteamboilerin, bookcentury1800, bookdecade1860
