Document jqKoJ48nDg9946RJk55174ZZ

5. The water line difference or distance between the water line of the boiler and the low point of steam main or dry return main should not be less than 24 in., because of the heavy drop in pressure from condensation in heating up a cold system. This difference should be increased 2 in. for every ounce pressure drop in the system. If the total pressure drop were 6 oz., the water line difference should be 6 X 2 + 24 or 36 inches. 6.. There should be a uniform drop in pressure between the source of steam supply and the farthest radiator on every riser. With a boiler pressure of 16 oz. and a maximum total pressure drop of 8 oz., the steam pressure at the supply valve of the farthest radiator on each riser should be 8 oz. The riser whose farthest radiator is 100 ft. from the main would be sized on a drop of 8 oz. per 100 ft. minus the drop in the main to Fig. 21. Connecting Two Boilers Using the Hartford Return Loop 58 American Society of Heating and Ventilating Engineers Guide, 1926-27 this riser connection; while one, 200 ft. from the main would be sized on a drop per 100 ft. __ one-half of the difference between the drop of 8 oz. and the drop in the main to the riser connection. The total drop, minus the drop in the main to the point of connection to any riser, divided by the equivalent length of the riser from the main to the farthest radiator in hundreds of feet, gives the drop per 100 ft. in the riser. For a total drop 6 oz., with the farthest radiator on riser No. 4, 200 ft. equivalent from the main and this riser connection 100 ft. from the source of supply, this riser would be sized on a basis of --^-- or 2J^ oz. drop per 100 ft. of riser. Table 33. Flow of Steam in Pipes P = Loss in pressure in lb. d = Inside diameter of pipe in inches L -- Length ot pipe in teet D = Weight of 1 cu. ft. steam W = Lb. of steam per min. / P D ds 3.6\ W2 L r -- u.oouxaz y -r d J D d5 Pressure Loss inOz. Col. 1 1p 87.04/----- y/ ioo Inside Dia. Pipe i 2.175 i 2 --3.076 3 3.767 4 4.350 IX m 2 5 4.863 6 5.328 3 7 5.754 3X 8 6.152 4 10 6.878 4M 12 7.532 5 14 8.138 6 16 ' 8.700 ` 7 20 9.727 8 24 10.655 9 28 11.509 10 32 12.290 12 40 13.756 14 48 15.069 16 80 19.454 -- 160 27.512 320 38.863 -- 480 47.652 Col. 2 1 ih 0.522 1.177 1.828 3.709 6.109 11.183 16.705 23.630 32.098 43.719 69.718 105.35 150.33 205.37 271.16 437.51 733.90 925.19 Steam Pressure By Gage Col. 3 ___ V 0.0 0.3 1.3 2.3 5.3 10.3 15.3 20.3 30.3 40.3 50.3 60.3 75.3 100.3 125.3 150.3 175.3 200.3 0.193 0.195 0.201 0.207 0.223 0.248 0.270 0.290 0.326 0.358 0.388 0.415 0.452 0.507 0.557 0.603 0.645 0.685 -- -- Length Pipe in Feet Col 4 v-- 20 40 60 80 100 120 140 160 180 200 250 300 350 400 450 500 600 700 800 900 1000 1400 2.240 1.580 1.290 1.120 1.000 0.912 0.841 0.793 0.741 0.710 0.632 0.578 0.538 0.500 0.477 0.447 0.407 0.378 0.354 0.333 0.316 0.267 Column lX2X3X4=lb. steam per min. will flow through a straight pipe for a given condition. - Example.--1 oz. drop -- 2-in. pipe -- 1.3 lb. press. -- 100 ft. long -- 2.175 X 3.709 X 0.201 X 1 = 1.615 lb. per min., then 1.615 X 60 -- 20 per cent = 77.28 lb. per hr. Preceding table does not allow for entrained water in low-pressure steam, condensa tion in covered pipe and roughness in commercial pipe, therefore reduce calculated capacities approximately 20 per cent. 59