TM 5-3895-374-24-2Figure 22Typical Oil Burner with Fixed Air Low Fire Start Fuel/Air Control ModeMECHANICAL OPERATION: The fixed air low fire start systemuses a two-step, two-stage Oil Pump (2) with a Simplex Oil Nozzle(9). A direct spark oil ignition system will normally be supplied, butcertain insurance company codes could require a spark ignited gaspilot* to provide ignition for the main oil flame. The nozzle flowrate pressures are taken at the Plugged Pump Nozzle PressureGauge Port (6). The low fire oil flow rate is set by adjusting the OilPump Low Pressure Regulator (8). The high fire oil flow rate is setby adjusting the Oil Pump High Pressure Regulator (3). For bothhigh and low fires, turn the adjustment screws clockwise toincrease the pressure and counterclockwise to decrease thepressure to the Nozzle. Approximate low fire pressures are 150 to225 psig and high fire, 200 to 300 psig. The Air Dampers (4) areadjusted and locked in place with the Air Damper Arms (5) forcorrect combustion values at the high fire rate. At light off, theMain Oil Solenoid Valve (1) is energized, allowing fuel to flow tothe Nozzle. The normally open Low Fire Solenoid Valve (7) allowsa reduced amount of oil to the Nozzle for low fire start. When theflame is proven by the flame detector’, the low fire solenoid valvecloses, providing full high fire pressure to the Oil Nozzle. Theburner operates at the high fire position until the system loaddemand is satisfied. Refer to page 31, Table 9 for specific nozzlepressures and firing rates. See page 11, Fig. 11 and the pumpmanufacturer’s bulletin supplied with the burner for additionalinformation.* Not shown in this depiction. See page 3, Fig. 1.Note 1The system depicted uses a two-stepSuntec oil pump. If a pump that does nothave the integral two-step function has beenspecified and supplied, it will be providedwith a N.C. nozzle bypass oil solenoid valveand a separate adjustable low fire reliefvalve. Refer to the oil piping diagram andthe oil pump manufacturer’s bulletinsupplied with the burner for specifics onyour system.Note 2Component operational sequencing willvary with the specific Flame SafeguardControl being used. Refer to the specificFlame Safeguard Control bulletin suppliedwith the burner for complete information.Figure 23Typical Oil Burner with Low-High-Off or Low-High-Low Fuel/Air Control Mode Using Webster 22R Oil Pump(page 3-968)
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