Document KoLr94w4x172J7gwXr110J9Q

Automatic Combustion Controls nmi/nted lales, safeguard! can quickly shut the fuel supply safety waive after a flame failure. In build-up of flammable prod ucts, you should solve the immediate problem with adequate combustion-air supply to the boiler room for purging and proper adjustment of burner airfuel ratio. Proper Safeguards. At beginning of this nrticle a set of numbered recom mendations pinpoint essential safe guards for both gat and oil Tiring. Cer tain basic requirements must be met.1 For gas (hey are: (1) Provide a com bustion safeguard and safety shutoff valves in both main- and pilot-burner gas lines. (Each should be approved and the combustion safeguard further approved for type of pilot uaed. Be ggj lain the safeguard causes the ujSy shutoff valves to close in a failure.)? (2) Provo the existence of a ^ pilot flame at a point where It. U'i reliably ignite the main burner, bef^j permitting the main aafety shutoQ^ valve to open. (This is a function'd {Continued on page 200) '1 Definitions and Specifications. 1. AulemaHe-iighted boilers. Unit where pressure- or tempera ture-controlled devices turn on fuel to main burner automatically. Control arrangement automatically provides (a) electric ignition source or electrle-lgnlted pilot flame, or (b) continuous-burning manually-lighted pilot for main burner. 2. Automatic combustion controls. Devices to vary firing rate with load changes and maintain a constant fuel-air ratio. $. Combustion safoguord. Control that senses flame presence end eauies a fuel-safety shutoff valvo to close In flame failure. Any eurrenlly approved combuation safeguard shuts off fuel to: (s) main burner by calling for closure of a safety shutoff valve 24 see alter receiving a flame-failure signal lb) pilot burner by calling for closure of pllol-cafely shutoff valve within 24 sec after flame-failure signal, unleu control provides a reliable ignition source for relighting pilot. Aotapprovcd aafety shutoff valve closes in not mere than 5 sec after coll for closure. 4. Supervised flame. A flame whose presence or absence is de lected by a combustion raleguard. Proved pilot, A pilot flame supervised by combustion safeguard that senses presence of pilot flame before opening the main burner's fuel-safety shutoff- 5. Flame-sanslng alomont. A flsme rad, photoelectric cell or photoconduetive foil of a combustion safeguard. A flame rod, generally not suitable for oil. is an electrode eitending Inin the gas flame (hat, because of the conductive property of Ionized gases in the flame, draws a current through ll lo the safeguard. Photoelectric cell emits electrons. Emission rate increases on exposure to luminous Himes and permits current flow to the combustion safeguard control circuit. Mounted outside the boilerfurnace, cell sights when flsme is supervised. Photoconduetive celft internal remittance lowers on etpoeure to both luminous nd nonluminous flames, thus permitting eurrent flow lo the combustion safeguard control circuit, suitable for both gas and oil. Mounted outside the boiler-furnace. 6. Programing combuation safeguard. On lighting off. it turns on ignition system, determines its running time, and when pilot and main fuel valves open. On failing to sente the flame, it shuts off all fuel and locks out. An approved recycling programing combustion safeguard auto matically proves the pilot and repeita (he lighting cycle once, following an accidental flame (allure. An approved Interrupted pilot repeat# the lighting cycle only after the trlaMer-ignJtion period la completed and before end of the call for heat. With the non-recycling type, both pilot and main-bomer-aatcly shutoff valves clase and lock out, and there 2a no ignition attempt after flame failure. Approved programing combustion safeguards work this way: a. Cos main burner. Pilot flame b proved by the combustion safeguard before letting the main gaa valve Open, and an inter rupted pilot ia used to limit trial-for-lgnitlon to IS see. b. OU main burner. Pilot flame b proved by the combuation safeguard before letting the oil valve open, trial-for-ignlllon Is limited to GO sec. With an unproved pilot, IS sec, with no recycle. 7. Trlal-fer-tgnltlon period. Period of time the programing combustion safeguard permits the main-burner fuel valve to be open before the main flame-sensing device m required to detect the main flame. If this flame is not detected, all fuel is shut off and locked out at once, and there is no further Ignition attempt. 8. Pilol-flame-oatablishing period, length of time the eombuitlnn safeguard permit* the pilot fuel valve to be open before the flame-sensing device b required to delect pilot or main 9a. Continuous pllol. Only the fireman can light it out turndown entire time the'boiler la in service, whether & burner is firing or not. Upon pilot-flame failure without the pnf ence of a supervised main flame, the combustion safeguard call for shutoff of both pilot and main burner fuel. 9b. Interrupted pilot. Deviee electric-ignited automatically ejd| e^'vaVdttHO INCANDESCENT lomps supplement 48-, 72-, 94*1n. lime there ia a coll for heat. Programing comburtlon taftgut^ Slimline lomps In this innollotion. The 150-wott In- usually cola off pilot fuel automatically at end of main bung)1 iriol-for-ignition period, to main flame supervision must Uut with a photoelectric, supervised, main oil flsme with ptoq)1 interrupted gss pilot, the pilot flame need not cut off automating until some predetermined time after trial-fer-ignillon period. is true provided the programing combustion safeguard interrjjS] the pilot flame detection (flame rod) circuit at end of Iriiltfl ignition period to main flame supervision must begin. In dtlal cate, should the pilot fail lo ignite upon o call for heat, the prs^l granting combustion .safeguard closes and locks nut the jfaJ safety shutoff valve after it has remained open not longer thu" pilot-flame-establishlng period of GO see. candescent units provide horizontal lighting for control boord. Luminous ceiling delivers overogo lighting level of 125 ft-c 9c. Intermittent pilot, ft Is electric-ignited automatically evs*d1 lime there is a call for heat Tt burns during the entire tims lk main burner fires, and rhot# off with the main hunter at end'd cal) for heal. Should (ha pilot fail to ignite upon o call for kq^ programing combuation safeguard closes and l<wka out the pOa safety ahutoff valve after permitting a pilol-Hamc-eitabliiMj period of not more than 60 sec. Acceptable Intermittent pilot works as follows: Main Burner--Css. Proved intermittent gaa pilot: With iW| fired main burner or burner unit and flame rod or photocaadk'l live ruperviaion, the flame rod or photoconduetive cell cscsO distinguish main from pilot flame. So there can he no ignition period nor supervision of the mein flame exclusively. M, these reasons the interrupted pilot b preferred. Main Burner--Oil. Proved intermittent gas pilot: With a pk#, njrCOtD-CATHODE lomps supply 52 ft-c fighting level. Room is mtoelectrie rupervised oil flame, locate the flame rod as nearly a ^vV7;i*40 ft, celling is 11 ft high. Light source ts 3500-k, white, possible to point where pilot flame insure# oil ignition from tW. pilot before the programing eomburiion safeguard permits taraht, 25-mm, 100-mo, cold-cothode lomps connected In series. Two lomps ore 17)4 in. obove each panel, spaced 14 In. opart on the ofl.' The only programing combustion safeguard appmrdi t|Modern Control-Room Lighting With...for this arrangement interrupts the pilot.flame-detection (flams t^lj V? circuit at end of trial-for-ignition period. ..tO. Unproved intermittent gas pilot: The trbl-for-ignition perladil ;the photoelectric or photoconduetive supervised oil flame la T* lied to IS tec. If the main flame is extlngobhed at end of Orb), foe-ignition period, the programing combustion safeguard clevij and locks out the pilot and moin-burner-safety ahutoff vehes. -,] iVttv;. An expanding pilot, lighted by the fireman, normally bun.^ $:& ...Luminous Ceilings a low torndown throughout the time boiler la in service, whelk# the main burner Is firing or not. Upon a call for heal the-(A*, automatically expand* to reliably ignite the main biimav'w. turns down at end of this burner's trisMor-Ignltioa period so iw?. flame supervision must begin. In the expanded condition, operate# end is safeguarded the same as an interrupted pilot. P '^iConiider a luminous ceiling lighting fixture large as Plastic used as light-diffusing medium ia finding many applications in the power field. On these three pages are over-all shadow-free luminous ceiling. Every square.Inch of a luminous ceil ing ii n source of low-brightness light. This ia In marked contrast to the "pin point'' lighting methods of yesteryear. The diffusing panels eliminate glare from the light source. Lighting values of 100 foot-candlea and higher can be had at the woiklng level without glare. The glare angle is Important in controlroom lighting. With individual lighting fixtures the glossy surface of tables, 10. Safe-start component check. A chocking circuit, ute^i built into the comburtion safeguard. It prevents lighting offy. room. Ceiling consists of the flsme relay conlaets are in an unsafe position. ;.'<! '*-list'llnfl tource, straight runs It. flower burner. Either gas or air, or both, are supplls^ij ^?liJomps with diffusing panels pressures exceeding, for gaa. the line pressure, and for air, atm* pheric pressure; this added pressure Is applied si the bttfl^j L*4j|he below wall to wall shown typical applications for controlroom lighting. The same basio lighting plan is being uaed for offices, banks, hospitals, laboratories, ete. In essence, the lighting scheme consists of a plastio light-diffusing bed below banks of fluorescent lamps producing, an even, glass-lop desks, instrument and.meter faces often pick up images of concern irated light ami reflect them, to the annoyance of the operating men. Diffusing Panels. In a luminous ceiling the ponels take light from a concentrated source ond diffuse it with high - 94 ENOINEESINO AND MANAGEMENT SECTION \% i.UWUAIT toga ENOlNEEIINO AND MANAGEMENT SECTION 93