File:Notes on heating and ventilation (1906) (14765230915).jpg

Identifier: notesonheatingve01alle (find matches)
Title: Notes on heating and ventilation
Year: 1906 (1900s)
Authors: Allen, John Robins, 1869-1920
Subjects: Heating Ventilation
Publisher: Chicago, Domestic engineering
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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allypitched toward the boiler so that the system maybe drained at that point. Water Line.—The water line is the height atwhich the w^ater stands in the return pipes. In awell designed gravity system it is seldom morethan six inches above the w^ater line of the boiler. Siphon.—When a vertical bend is made in thereturn main so that the return dips down and re-turns to its former level, it is called a siphon. Allsiphons should be provided with a drain (or petcock). Dams.—Sometimes the water level in the boileris lower than that desired in the piping system andan inverted siphon is placed in the return pipe. Noreturn will then take place until the water hasreached the highest point of this bend in the re-turn. A dam should be provided with an air cock. Water Seal.—Where a return pipe enters the Notes on Heating and Ventilation 103 return main below the water line it is said to besealed. It is customary to seal all main riser dripsand returns from indirect radiators and pipe coils.
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Fig. 19. Water Hammer.—The rattline and the ham- Jr» mering often heard in pipes is called water ham-mer. It is caused by steam coming in contact withwater or surface in the pipes which is colder thanitself. A sudden condensation results and a vacuum 104 Notes on Heating and Ventilation is produced into which the water rushes. Theblow is often so severe as to crack the fittings andspring the valves. It is most apt to occur whenthe plant is first started. Accidents from this causemay be avoided by admitting the steam very slowlyat first. Steam Traps.—Steam traps are vessels usuallyplaced between the steam and the return system toallow the water of condensation to be carried tothe return system without steam entering the re-turns. By the use of steam traps the steam andreturn mains may have a wide difference of pres-sure. Steam traps are objectionable as they areliable to get out of order and require frequent re-pairs. The systems of piping may be grouped underthree general heads.

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