North American Air/Gas Ratio Regulators
Instructions 7218-2
INSTALLATION--GENERAL A1. Install a gas shutoff valve upstream of regulator.
To minimize turbulence effects, locate connection on the air line at least 5 pipe diameters downstream and 3 diameters upstream of any valve or fitting. Hole should be drilled so drill is parallel to shaft of valve.
A2. Mount 7218 Regulator horizontally with diaphragm case below gas line --regulator cannot function if the diaphragm is not horizontal. Arrow on body must point in direction of gas flow.
8654 or 8655 Bleeder
5D min.
3D min.
Control valve
A3. Allow sufficient clearance above floor or other piping to permit adjustment.
air
lock open
bleed line
Impulse line
A4. 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 or flanges to permit removal for servicing.
±2 osi
low pressure gas
4D min.
Protect regulator from excessive heat. If ambient temper- ature exceeds 180°F, use Viton diaphragms.
combustion chamber
Avoid welding near regulator when installing adjacent piping: Weld spatter may roll through pipe into a regulator and burn holes through the diaphragm.
10D min.
Figure 3.
INSTALLATION, For NOZZLE-MIX BURNERS B1. Install a limiting orifice valve between regulator and burner. B2. If minimum gas inlet pressure exceeds maximum air pressure by 2 or more osi, simply cross-connect regulator vent to main air line downstream of control valve (Figure 1).
Apply pipe compound to threaded pipe ends, not to threads on regulator body.
A5. One regulator must not supply more burners than are con- trolled by one air valve.
A6. For nozzle-mix systems, gas inlet pressure should be greater than air impulse pressure by at least 2 osi, or pressure drop for regulator size selected. Inlet pressure should not exceed 32 osi except in special cases. A7. When cross-connecting regulator vent to main air line or to combustion chamber or outside, use 3⁄8 " tubing for up to 10 ft, ½" or larger for longer runs. A8. To attach cross-connection or impulse line to an air line, weld a half coupling on top or side of air pipe; then drill a hole through pipe (½" hole if bleeder is used, otherwise about the ID of tubing selected in step A7 above). Remove burrs from the inside.
Control valve
5D min.
3D min.
Butter fl y valve lock open
air
Figure 1.
Impulse line
Nozzle-mix burner
gas
4D min.
10D min.
shut- off
Limiting ori fi ce valve
Metering ori fi ce
tee for gauge
Ratio regulator
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