Sheet 4723-3 Page 2
B. INSTALLATION AND ADJUSTMENT 1. Slow motor timing and careful valve linkage setting will contribute to smooth operation. To set linkage for slow open- ing (using the "dwell" or "lag" characteristic of the linkage) by setting start point ahead of dead center, if motor design permits (see Figure 2). 2. Bleeders should be avoided if possible, but should one be re- quired, use ½ " pipe or 5⁄8 " O.D. tubing for impulse and bleed lines. Check pressure drops in all equipment before setting bleeder. To set bleeder, measure gas pressure at the outlet of the ratio regulator against pressure in the impulse line or at a tap in the main air header if necessary, but not at the burner. 3. If possible, use an oxygen analyzer to set the air/fuel ratio. Otherwise use metering orifices. If orifices are not available, check ratio with a torch at tube exhaust when the tube is hot adjust the limiting orifice valve just lean enough to eliminate flame from combustibles leaving the tube. 4. With gas piloted burners, follow bulletin instructions on low fire air rate to prevent burner damage from overheating. Low fire should not be lean or rich. Overheating occurs with a lean fire, sooting with a rich fire. 5. Changing the percentage of primary air also changes total air flow, so readjustment of air/fuel ratio becomes necessary. The bulletin gives air rates only at the extremes of primary air adjustment. Intermediate values are not available. 6. Even when a long flame is desired and burner is set for minimum primary air, turn primary air screw out 1/4 turn from closed to ensure that a small amount of air purges the primary air tube. This will help ensure proper UV cell opera- tion. 7. An interrupted pilot prevents possible burner gas tube dam- age from overheating with the pilot. 8. Pipe burner air to minimize spin as the air passes through the burner body. Do not use an elbow close to the burner. Gas manifolding between control regulator and burners should be kept short. 9. To reduce CO at low fire, bias the ratio regulator so that the burner will run with more excess air at low fire. The optional air jet will allow the burner to maintain 2-3% O 2 throughout the entire turndown range while maintaining low CO emis- sions. 10. The use of jet air at 16 osi will reduce the maximum ex- cess air limit at low fire rates. If higher excess air rates are desired, lowering the jet pressure will increase the excess air limit while still suppressing the formation of CO at low fire.
C. TROUBLE-SHOOTING Carefully check the following conditions if the burner does not operate properly: 1. Internal gas tube gasket (carbon ring) must be in good con- dition. It is prudent to use a new gasket when reassembling burner. 2. Flame retention cup may have deteriorated from over heat- ing due to improper ratio adjustment. 3. Burner mounting flange must be tight against the tube. Gas- kets are available. 4. Pipe sealant, paint or grease on the spark plug or "yoke" will block the electrical ground and prevent or weaken the spark. 5. Check direct spark igniter for wear. The gap should be set for 0.04 to 0.08 inches. The igniter should be placed in the burner so that the ground rod faces away from the radiant tube. 6. If pilots howl, change their air/fuel ratio. This is a very sensi- tive adjustment. Raising or lowering mixture pressure may also help quiet pilots. 7. If pilot will not light, check for spark at the plug and gas at the mixer. If both are present, remove and clean pilot tip. Make sure all piloting ports are clean: Plugging of one hole can prevent lighting. 8. If an 8666 Testip is used to allow the operator to see the type of pilot flames he is getting, it should be located in a semi-dark area, or viewed against a dark background. A well adjusted gas pilot flame is such a pale blue as to be nearly invisible in full daylight. 9. If the UV signal is too weak try adding more primary air by turning the air adjustment screw counterclockwise. 10. Radiant tube resonating problems can often be reduced by changing the primary air setting or adding a baffle to the tube exit.
Figure 2. Linkage of an 1126 Butterfly Valve with a Honeywell Motor at the "off" position. This ar- rangement provides slow opening.
WARNING: Situations dangerous to personnel and property may exist with the operation and maintenance of any combustion equipment. The presence of fuels, oxidants, hot and cold combustion products, hot surfaces, electrical power in control and ignition circuits, etc., are inherent with any combustion application. Components in combustion systems may exceed 160°F (71°C) surface temperatures and present hot surface contact hazard. Fives North American Combustion, Inc. suggests the use of combustion systems that are in compliance with all Safety Codes, Standards, Regulations and Directives; and care in operation.
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Fives North American Combustion, Inc. 4455 East 71st Street - Cleveland, OH 44105 - USA www.fivesgroup.com
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