Document ExOjLq6LmXrb2jEX3YV4dryYL

American Society of Heating and Ventilating Engineers Guide, 1936 heating system requirements. These valves are generally of the angle type and are usually made of brass. Graduations on the heads or lever handles are often'supplied to indicate the relative opening of the valve in any position. Standard roughing-in dimensions for angle-type valves are given in Table 12. Automatic control of steam supply to individual radiators can' be Table 11. Proposed Dimensions of Steel Welding Neck Flanges for Maximum Steam Service Pressure of 300 Lb per Sq In. (Gage) at a Temperature of 750 F Chapter 34--Pipe, Fittings, Welding fpr use in hot water heating systems are of less complex design, one type consisting of a simple butterfly valve, and another of a quick opening type in which a part in the valve mechanism matches up with an opening in the valve body. In one-pipe steam-heating systems, automatic air valves, are requiredat the radiators. Two common types of air valves available are the vacuum type and the straight-pressure type. Vacuum valves permit the expulsion of air from the radiators when the steam pressure rises and, in addition, act as checks to prevent the return of air into the radiator when Table 12. Standard Roughing-in Dimensions Angle Type Valves Nominal Pipe Size . Diam. OF Flanob Thick-. NESS OF Flange Min. Diam. of Hub Hub Diam. Beginning OF Cbamper 0QX H *2. 2% 3 3% 4 5 6 8 10 12 14 O. D. 16 O. D. 18 O. D. 20 O. D. 24 O. D. 6% m m 9 10 11 12% 15 17% 20% 23 25% 28 30% 36 % 1 1% 1%6 1% .1% 1%6 1% 1% 2 2% 2% 2% 2% 2% 3%fi 3^6 4% 5% 5% 7 8% io% 12% 14% 16% 19 21 23% 27% 2.38 2.88 3.50 4.00 4.50 5.56 6.63 8.63 10.75 12.75 14.00 16.00 18.00 20.00 24.00 Length Thru Hub Y 2% 3 3% 3%fi 3% 3% 3% 4% m 5% 5%' 5% 6% 6% 6% Diam. FOB Standard Pipe A 2.07 2.47 3.07 3.55 4.03 5.05 6.07 7.98 10.02 12.00 13.25 15.25 17.25 19.25 23.25 Diam. FOB Extra Strong Pipe Diam. OF Bolt Circle A 1.94 2.32 2.90 3.36 3.83 4.81 5.76 7.63 9.75 11.75 .... 5 5% 6% 7% 9% 10% 13 13% 17% 20J-2 22% 24% 27 32 No. OF Bolts 8 8 8 8 8 8 12 12 16 16 20 20 24 24 24 Size OF Bolts H % % % % % % J1 1 i% i% i% 1% m i% For sizes below 2 inches use'dimensions of 600 lb flanges. All dimensions given in inches. \ A raised face of l/ in. is included in thickness offlange minimum.. It is recommended that the taper of the' hub should not exceed 6 degrees for a reasonable distance back of the chamfer in order to reduce the heat transfer while welding. effected by use of direct-acting radiator valves having a thermostatic element at the valve, or near to it: The direct-acting valve is usually an angle-type valve containing a thermostatic element which permits the flow of steam in accordance with room temperature requirements. These valves usually are capable of adjustment to permit; variation in room temperature to suit individual taste. Ordinary steam valves may be used for hot water service by drilling a Vf6-in. hole through the web forming the seat to insure sufficient circulation to prevent freezing when the valve is closed. Valves made particularly 624 R,Xh.eJtf/,?ard'Zaticm 1 the R?;hing-in Dimensions of Angle Steam and Hot Water, and Modulating tte Valves aid'FiTun^InduM^ Y coo`>erat,n f the Manufacturers Standardisation Society of a vacuum is formed by the condensation of steam after the supply pressure has^dropped. Ordinary air valves permit the expulsion of air from the radiator when steam is supplied under pressure, but when the pressure dies down and a vacuum tends to be formed the air is drawn back into the radiator. A system supplied with vacuum valves will heat more quickly and stay warm longer than one provided with straight pressure air valves; , thus it will effect considerable economy of fuel because the idle period during which no heat is delivered is shortened. Automatic air valves are provided with a float to close them in case the radiator becomes flooded with water because it does not drain properly. . 625