GAS SUPPLY PIPING

TM 5-3895-374-24-2 GAS SUPPLY PIPING Gas piping should be sized to provide required pressure at the burner train inlet manual shutoff cock, when operating at the maximum desired fuel input. All gas piping should be appropriately pressure tested to ensure leak free operation. It is recommended that a dirt pocket or trap be piped into the gas supply system just ahead of the burner train inlet manual shutoff cock. When testing with pressures higher than the maximum pressure ratings of the gas train components, be sure to isolate these components and test their piping for gas maximum main gas train and/or pilot gas train components pressure is 1/2 psig. (14" W.C.). Refer to Table 3 for information relating to the sizing of gas supply piping. These charts are based on the general flow characteristics of commercially produced black wrought iron pipe. If in doubt regarding flow capabilities of a chosen line size, the next largest size is recommended. Refer to page 9, Figs. 8 and 9 for typical gas piping schematics to meet U.L. requirements in the C burner firing ranges. Table 3 Capacity of Pipe · Natural Gas (CFH) With Pressure Drop of 0.3" w.c. and Specific Gravity of 0.60 Pipe Length Pipe Size - Inches (IPS) In Feet 1 1¼ 1½ 2 2½ 3 4 10 520 1050 1600 3050 4800 8500 17500 20 350 730 1100 2100 3300 5900 12000 30 285 590 890 1650 2700 4700 9700 40 245 500 760 1450 2300 4100 8300 50 215 440 670 1270 2000 3600 7400 60 195 400 610 1150 1850 3250 6800 70 180 370 560 1050 1700 3000 6200 80 170 350 530 990 1600 2800 5800 90 160 320 490 930 1500 2600 5400 100 150 305 460 870 1400 2500 5100 125 130 275 410 780 1250 2200 4500 150 120 250 380 710 1130 2000 4100 175 110 225 350 650 1050 1850 3800 200 100 210 320 610 980 1700 3500 Table 3A Correction Factors Specific Gravity Pressure Drop Other Than 0.60 Other Than 0.3 Specific Multiplier Pressure Multiplier Gravity Drop 0.50 1.10 0.1 0.577 0.60 1.00 0.2 0.815 0.70 0.926 0.3 1.00 0.80 0.867 0.4 1.16 0.90 0.817 0.6 1.42 1.00 0.775 0.8 1.64 Propane - Air 1.0 1.83 1.10 0.740 2.0 2.58 Propane 3.0 3.16 1.55 0.622 4.0 3.65 Butane 6.0 4.47 2.00 0.547 8.0 5.15 Note: Use multiplier at right for other specific gravities and pressure drops. Table 4 Equivalent Length of Fittings in Feet Pipe Size (IPS) 1 1.25 1.5 2 2.5 3 4 Std. Tee through Side 5.5 7.5 9.0 12.0 14.0 17.0 22.0 Std. E11 2.7 3.7 4.3 5.5 6.5 8.0 12.0 45 E11 1.2 1.6 2.0 2.5 3.0 3.7 5.0 Plug Cock 3.0 4.0 5.5 7.5 9.0 12.0 16.0 Table 5 Gas Train Components Supplied for Standard U.L. Burner Requirements See Gas Flow Schematics Fig. 8 and 9 for additional information. Fuel Air Control Modes of Operation On/Off Low/High/Off Low/High/Low Modulating Main Gas Cock XU XU XU XU Main Gas Pressure Regulator XU* XU XU XU High and Low Gas Pressure Switches OU X¹U X¹U X¹U Automatic Main Gas Valve XU* X X XU Automatic Main Gas Valve with Proof of Closure O X¹ X¹ X¹ Main Auxiliary Gas Valve O X² X² X² Leak Test Gas Cock XU X X XU Pilot Cock Pressure Regulator & Solenoid Valve X X X X Modulating Butterfly Valve N/A N/A N/A X Side Tee Orifice Assembly X X X N/A Main and/or Pilot Gas Pressure Gauge O O O O (page 3 - 960)