Document vV5yeVgkBZ4gbO8VgJnzvkbbR

392 CHAPTER 26 1960 Guide dripped into the wet-return, the air venting at the end of the main is accomplished by an air vent passing through a thermostatic trap into the dry-return line as shown in Fig. 49. On low-pressure or vacuum systems, the ends of the steam to take place. The low-pressure steam therein gen erated is passed directly to the low-pressure steam mains, and the condensate is discharged through a second trap to the low-pressure or vacuum return. A typical arrangement of a flash leg, with sizes required for varying capacities, is given in Fig. 52. CONNECTIONS TO HEATING UNITS Riser, radiator, and convector connections must not only be property pitched at the time they are installed, but must STEAM MAIMn. of Offset Pipe steam mains are dripped and vented into the return through drip traps opening into the return line. A float and thermo static type trap is recommended for dripping steam mains and risers as indicated in Figs. 50 and 51. The dripping of high-pressure mains, or of equipment using high-pressure steam into low-pressure or vacuum re TtCftMOSTATIC MT RETURN MAI^--T OIRT POCKET Fig. 50.... Dripping End of Steam Main into Dry Return RISERGATE WU.VE. STRAINER* \*-------- ^ FLOAT AW\A TWAMOSTATIC J \ fig. 49 .... Dripping End of Main into Wet Return turns, is generally accomplished by the use of a flash tank or leg into which the high-pressure trap is arranged to discharge. This tank provides the required space for the flashing from high-temperature condensate to low-pressure ORT RETURN-"* OIRT ' J MAIN POCKET* Fig. 51.... Dripping Keel of Riser into Dry Return be arranged so that the pitch will be maintained under the strains of expansion and contraction. These connections may be made by swing joints which permit the expansion or con traction to occur under heating and cooling without bending of pipes. To take care of expansion in long risers, either expansion joints of commercial construction or pipe swing joints are used. Anchoring of pipes between expansion joints is desirable. Two satisfactory methods of making runouts for one-pipe systems for either the up-feed or the down-feed type are Table 12 .... Dimensions Applying to Fig. 52 Steam Heating Systems PLAN 393 Rg. 57 .... Typical Connections to finned Pipe Convector Rg. 58.... Typical Connections to finned-Tube Blast Heating Coils Arranged for Series Flow of Air Radiator Connections HX MAM 3 A RETURN 5=o=> kPOCKET^ CCCENTRC AT LEAST Iff---------- \oU WATER LINE Rg. 55.... Two-Pipe Connections to Radiator Hung on Wall Rg. 59.... Typical Connections to Rnned-Tube Blast Heating Coils Arranged for Parallel Flow of Air Rg. 52.... Flash Leg Installation for 80 Psi Maximum Steam Working Pressure Rg. 60___ Typical Connections to Finned-Tube Blast Heating Coils of the Steam Distributing or Nonfreeze Type