NOZZLE MIX SYSTEMS
Table 2 FACTORS for correcting capacity for pressure drop.
pr. drop, osi
factor 0.707
pr. drop, osi
factor
1
8
2.00 2.24 2.45 2.65 2.83
2
1.00 1.12 1.22 1.41
10 12 14 16
2 1/2
3 4 6
1.73
REGULATOR INSTALLATION - GENERAL
1. Install a gas shutoff valve upstream of the regulator. 2. Mount regulator horizontally. Regulator cannot function if the diaphragm is not horizontal. This arrow on the body must point in the direction of gas flow. 7218 diaphragm case should be below the gas line. 3. Install regulators in clean pipe lines of adequate size, free from dirt, scale and chips. Mount regulator close enough to mixers or burners to avoid excessive pressure drop. Install unions of flanges to permit removal for servicing. Protect the regulator from excessive heat. Ambient temperature should not exceed 180 degrees F (350°F if Viton diaphragms are used). Avoid welding near a regulator when installing adjacent piping as weld spatter may roll into a regulator and burn holes through the diaphragm. Apply pipe compound to threaded pipe ends, not to threads, on the regulator body. 4. One regulator should not supply more burners than served by one mixer or controlled by one air valve. 5. For aspirator mixer (zero gas) systems, best control is obtained with at least 2 osi† greater than air impulse pressure. When the regulator's vent is connected to the combustion chamber, the furnace pressure must be added to the gas pressure requirement. Gas inlet pressure should not exceed 2 psi except in special cases. 6. When cross-connecting the regulator's vent to the combustion chamber, main air line, or outside, use 3/8 " tubing for up to a 10 ft run; ½" (or larger) tubing for longer runs. 7. To attach the cross-connection or impulse line to an air line, install a tee or weld a half coupling on the top or side of the air pipe and then drill a hole through the pipe, (½" hole if a bleeder is used, otherwise about the ID of the tubing selected in step 6 above). † Or pressure drop for which the regulator size was selected.
25
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