Document Lpx350Nbw7NB3o0RKY84JL0aX

HEATING VENTILATING AIR CONDITIONING GUIDE 1940 CHAPTER 16. PIPING FOR STEAM HEATING SYSTEMS Branches from steam mains in one-pipe gravity steam systems should use the preferred connection shown in Fig. 18, but where radiator condensa tion does not flow back into the main the acceptable method shown in the same figure may be used. This acceptable method has the advantage of giving a perfect swing joint when connected to the vertical riser or radia tor connection, whereas the preferred connection does not give this swing Fig. 12. Supply and Return Con nections for Heating Units of Central Fan Systems Fig. 13. Typical Connections to Central Fan System Heating Units Exceeding 12 Sections Horizontal return pipes may be carried past doorways and other ob structions by using the scheme illustrated in Fig. 17. It will be noted that the large pipe, in this case, runs below the. obstruction and the smaller one over it. Fig. 15. Dripping Main Where it Rises to Higher Level Fig. 16. Looping Main Around Beam Fig. 17. Looping Dry Return Main Around Opening Acceptable method Preferred method Fig. 18. Methods of Taking Branch from Main To find length C-multiply A by constant for angle B Fig. 19. Constantsfor Determining Length Offset Pipe Fig. 20. Dirt Pocket Connection Fig. 21. Dripping End of Main into Wet Return Fig. 22. Dripping End of Main into Dry Return Fig. 23. Dripping Heel of Riser into Dry Return without distorting the angle of the pipe. Runouts from the steam main are usually made about 5 ft long to provide flexibility for movement in the main. Offsets in steam and return piping should preferably be made with 90-deg ells but occasionally fittings of other angles are used, and in such cases the length of the diagonal offset will be found as shown in Fig. 19. Dirt pockets, desirable on all systems employing thermostatic traps, should be so located as to protect the traps from scale and muck which 309