NOZZLE MIX SYSTEMS
TROUBLE SHOOTING 7218 AIR/GAS RATIO REGULATORS — CROSS-CONNECTED
A. Symptom: At high fire, outlet pressure is less than impulse pressure taken near connection to regulator. Causes: 1. Insufficient supply pressure or supply line is undersized. 2. Regulator is undersized. 3. Leak around lower diaphragm or adjustment plug. 4. Hole in control (large) diaphragm. B. Symptom: fire goes lean at "High." Causes: 1. Improper location or installation of impulse tap.
2. Leaking impulse line. 3. Dirty bleeder orifices. 4. Bleeder not cross-connected to combustion chamber which has positive pressure. 5. Any of the conditions listed under "A."
C. Symptom: fire goes rich at "Low."
Causes: 1. Spring adjustment set "positive." 2. Hole in small diaphragm.
3. Limiting orifice open beyond normal to compensate for any of condition under "A" and "B" above. 4. Bleeder not cross-connected by combustion chamber which has negative pressure (suction). 5. Valve not seating because of dirt or damage.
D. Symptom: Fire goes lean at "Low."
Causes: 1. Spring adjustment set "negative."
2. Bleeder not cross-connected to combustion chamber which has positive pressure.
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