Assessments - 2, GPA: 4
(
)
)
|
Facilidade de uso
The temperature we correct to is 60° F. That’s close to the temperature of the ground, so usually it’s not necessary to correct for temperature from underground lines. 0 Measure the gas temperature at the meter. 0 Add 460 to the gas temperature and divide 520 by the result to obtain the correction factor. 0 Multiply the pressure corrected flow rate times the temperature correction factor. Example: The meter in the example is connected to an above ground line on a hot day and shows 100° F gas temperature. 460 + 100 = 560; 520 / 560 = 0.929; 465 x 0.929 = 432 CFH corrected for pressure and temperature. This figure is often called SCFH (for standard cubic feet per hour). BTU’s and MBH Natural Gas The BTU content of natural gas varies from one location to another, and even from day to day at a fixed location. For firing estimates it is usually assumed to be 1000 BTU’s per standard cubic foot. To calculate BTU/Hr firing rates multiply SCFH times 1000. Example: 432 SCFH x 1000 = 432,000 BTU/Hr. MBH stands for thousands of BTU’s per hour. Since 1 cubic foot of natural gas contains 1000 BTU, 1 MBH equals 1 SCFH of gas fl ow. Example: 432 SCFH = 432 MBH LP (Liquified Petroleum) Gas The BTU content of LP gas varies with the relative quantities of propane and butane in each delivery of gas and changes as liquid level in the tank falls. For firing estimates it is usually assumed to be 2,500 BTUs per standard cubic foot. To calculate BTU/Hr firing rates multiply SCFH times 2,500. Example: 432 SCFH x 2500 = 1,080,000 BTU/Hr. MBH stands for thousands of BTU’s per hour. Since 1 cubic foot of propane gas contains 2,500 BTU, 1 MBH equals 0.4 SCFH of gas fl ow. Example: 432 SCFH = 1,080 MBH 24 Section: Start the Burner Figure 14A - Manifold to Furnace Pressure Drop vs Rate CG15 * 1800 1600 1400 1200 CG15.4S 0 0.5 11.5 2 2.5 3 3.5 44.5 Pressure Drop, In. WC Rate, MBH 1000 CG15.3S CG15.2S 800 CG15.1S 600 400 200 0 Figure 14B - Manifold to Furnace Pressure Drop vs Rate CG25* 3500 3000 2500 CG25.5S 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Pressure Drop, In. WC Rate, MBH 2000 CG25.4S CG25.3S 1500 CG25.2S CG25.1S 1000 500 0 * Charts represent both natural and propane gas. 25CG15, CG25, CG50 Burner Manual Section: Start the Burner Figure 14C - Manifold to Furnace Pressure Drop vs Rate CG50* 6000 5000 4000 3000 2000 1000 0 * Charts represent both natural and propane gas. 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Pressure Drop, In. WC CG50.5S CG50.4S CG50.3S CG50.2S CG50.1S Rate, MBH Check Operation and Safety Controls Testing by Qualified Technician Required. Failure to properly test and verify the correct functionof operation and safety controls could lead toequipment malfunction and result in asphyxiation, explosion or fire. • The testing of operation and safety controls requires technical training and experience with commercial gas burning systems. • Carefully follow the manufacturer’s instructions supplied with the controls. • Verify the correct function of all operation and safety controls used in the installation. • If instructions are not available, use the following recommended procedures and record all results in a start-up log. • Refer to Figure 7 for typical test points and component locations. 1. High limit – To check the High Limit, raise the temperature or pressure of the operating control to a higher level and lower the limit to a setting less than the operating control. Run the burner until the high limit opens and shuts the burner off. Adjust the controls back to the desired settings. 2. Operating control – Run the burner until the operating control shuts it off. If necessary, make adjustments to ensure the control cycles the burner in the desired temperature or pressure range. Operating controls should be set to minimize the number of firing cycles that the burner runs. High cycling rates increase the possibility of light-off lock outs. 3. Low water cutoff (LWCO) – With the burner firing, open the blow down valve on the low water cutoff, if applicable. As the water level drops, the LWCO switch contacts open and shut the burner off. When the water level rises, the LWCO contacts close and restart the burner. Monitor the LWCO switch operation in relation to the water level in the sight- glass for synchronization. 4. Airflow proving switch – With the burner fi ring at its lowest rate, loosen the tubing connection to the airflow proving switch. A loss in air pressure at the tubing should immediately cause the diaphragm in the switch to open and recycle or lockout the safeguard control. 5. Low gas pressure switch – With the burner firing and a manometer attached to a test port near the low pressure switch, gradually close the main leak test cock to shut off the gas supply. Note the pressure at which the low gas pressure switch opens and shuts the burner off. Manually reset the switch. The low gas pressure switch should be set at half of the normal supply pressure in the line. 26 Section: Start the Burner 6. High gas pressure switch – With the b...
Este manual também é adequado para os modelos :Greeley - CG15 (2.99 mb)
Greeley - CG25 (2.99 mb)