Ordering Instructions | Gas Ratio Regulators
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When installing North American 7218/7219A equipment please follow the diagram to the right.
ORDERING INSTRUCTIONS
7218 - -
"Blank" Standard V = (FKM) diaphragms and O-rings RK = repair kit VRK = (FKM) repair kit UK = upgrade kit for -5,-6,-7 VUK = (FKM) upgrade kit for -5, -6, -7 K= no brass internals (obsolete)
Product Number
7218 7219A
Pipe Code
SIZING EXAMPLES
A nozzle-mix system requires 5000 cfh of natural gas. Gas inlet pressure is 12 osi; maximum air pressure at the burner is 8 osi.
available gas pressure minus 2 osi drop through regulator). For the required 5000 cfh in this example, select a 7218-5 from Table 1. If system was premix instead of nozzle-mix, regulator outlet pressure is zero, and pressure drop through the regulator would equal inlet gas pressure (12 osi). Table 2 factor is 2.45; 5000 ÷ 2.45 = 2040 cfh. Select a 7218-3 Regulator from Table 1.
When cross-connected, outlet gas pressure is 8 osi at high fire; pressure drop across regulator is 12 – 8 = 4 osi. Table 2 factor for 4 osi is 1.41; 5000 cfh ÷ 1.41 = 3546 cfh. In the 0.6 sp gr column of Table 1, select a 7218-4 Regulator (rated at 4800 cfh.) If air pressure at the burner was 16 osi but available gas pressure was still only 12 osi, a bleeder would be required in the cross connection. For minimum bleed†, select regulator for required cfh directly from Table 1 (2 osi) capacities; then bleed cross- connected air impulse at high fire from 16 osi to 10 osi (12 osi
REPAIR AND UPGRADE KITS For repair and upgrade kits see: Sheet 7216/7218/7219A/7349A.
† Minimum bleed is desirable to realize highest possible impulse pressure for widest possible turndown. The "Standard" regulator now comes with no brass internals, and can be used in place of the obsolete - K model
Bulletin 7218/7219A Page 4
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