95 CHAPTER 12 Low Pressure Domestic Burners The principle of vporiing oil in low pressure burner is shown in fig. 1. Air nd oil re mixed within the nole, then Y ---U OIL NOZZLE j FIG. 1. Digrm showing principle of vporiing oil in low pressure oil burner. spryed in vpor form through n opening 3 to 4 times lrger thn the opening employed in high pressure noles. The ir-oil vpor is gin mixed with secondry ir produced by the fn s it leves the nole. It is climed tht higher combustion efficiency with lower fuel costs nd ultimtely less gllonge consumption re the result of the mixing of ir nd oil twice.
LL L. C LL CL IL (D Z LI lo - LL. -J L.' Cl) ILl 'U I.. U).. c3 4 ''- Z W - J 9 I- J ILl LL o -4. ED SL4 C13 ) 'bc ii) Cd ) 'Ec I 4 2be' CO ' Cd bo o c wcd ) O Co.- ) ;- V. CvS - - )4 )).4) ' C_) _1 1-.,.c +)4 CO E4 - ) Q bo 1-4 -- Cl) wo&) +4. - OO). wo 4 i C1 1-96A Ans. The primry ir pump delivers ir to the nole t upproximtely 1 lbs. This primry ir drws oil (which flows ut lmost ero pressure) from the nole nd mixes with this oil in the form of very fine ir-oil vpor spry, which in turn Is gin mixed with the secondry ir to crete fine vpor spry. The first stge intke pump drws oil from the oil storge tnk. The high vcuum creted when drwing oil from buried oil storge tnk cuses ir to be seprted from the oil so tht when it leves the intke pump into the purging reservoir, it is in fom form, tht is, fine ir bubbles nd oil. It is here the bubbles go to the top of the reservoir then sent bck to the buried oil storge tnk while pure oil settles in the lower portion of the reservoir, from which it is pumped into the pressure chmber. This oil under pressure motivtes the free floting piston which meters the mount of oil permitted to go to the nole when the shut off vlve is open. The cpcity is vried by the djustment screw. Combustioneer Hydr-vted Low Pressure Fuel Unit. This is low pressure two stge self purging reservoir oil metering pump with cpcity from.5 to 3 gllons per hour. The fuel unit is shown in fig. 3. Before ny pump will function it is necessry tht oil be brought from the tnk to the pump, nd it should be esily understood the greter the sie nd length of piping, the longer it will tke for oil to rech the pump. It should lso be esily understood tht ll ir must be bled from the vrious chmbers of pump fter it hs received oil from the tnk on one line system. The hydr-vted pump hs n oil pressure chmber, wherein n oil pressure of bout 5 lbs. per sq. in. is utomticlly mintined to open nd close the shut off vlve on the oil line to nd from the nole. This oil pressure lso motivtes the free floting piston through the rotting vlve. In servicing, n ir pressure guge (rnge to 15 lbs. per sq. in.) my be used nd cn be ttched. The djusting screw for the ir pressure is shown t 5. To rech this ir djusting screw with screw driver it is necessry to remove its protecting pipe plug. By turning this ir djusting screw clockwise, the
Trw P ii r flr m, / Ri i r r ir pressure is incresed, nd by turning the ir djusting screw count clockwise the ir pressure is decresed. If pump do not perform stisfctorily, djust ir pressure. This n be determined by n unstisfctory flme. Willims Oil-O-Mtic Model 5-1 Low Pressure ( Burner. When the burner strts, the pressure built up. the dischrge side of the ger pump E, fig. 4, is trnsmitt to the lower side of the diphrgm S, in the hydrulic vlve V. HYDRAVATED FUEL UNIT 2. RETURN (FRONT OR BACK OF PUMP) E 3 - INLET t (FRONT OR BACK OF PUMP) 4. PISTON 1 ADJUSTING SCREW C -u V FIG. 3. Combustioneer Model E2R Hydr-vted two stge self purging reservoir unit. Illustrtion shows the fuel unit. When the motor speed reches pproximtely 28 r.p.m. suffici pressure will be ttined to overcome the spring tension of spring thus rising the piston PP off its set, which permits metered oil from metering pump to flow through the hollow vlve stem T, to the oil tube During the opertion, oil is pulled in through the oil inlet port SL, the striner housing F. It then psses through screen A, nd over ti B. From the tube, oil is crried through pssge to the inlet side of 1
96D 96E ger pump B. A pressure of bout 14 lbs. per sq. in. is built up on t dischrge side of the pump. This pressure is trnsmitted through pssge to the lower side of the diphrgm S, in the oil vlve. T oil builds up sttic hed pressure under the diphrgm S, bec there is ctully no flow of oil. The flow of oil from the ger pump E, to the pressure regultor G. The pressure regultor G, nd the metering pump I, re in the sme housing nd both prts re built into one rotor. The pressure regultor controls the operting pressure of the ger pump. The pressure tht built up hs two primry functions: 1, it opens the oil vlve, nd it ssures the metering pump of positive s well s uniform volume of oil vilble to the metering pump pistons. During opertion, the steel bll H, in the pressure regultor is held on its set ner the perimeter of the rotor by centrifugl force. As oil pressure is built up, the pressure of the oil forces the bll off its set, thus permitting excess oil to flow pst the bll into the by pss chmber BC. By pssed oil is delivered from the by pss chmber through the hollow portion of the driv shft nd into the by pss pssge. Ques. Wht is the hook up nd opertion on one nd pipe systems? Ans. On one pipe systems, internl by pss screw is moved nd excess oil is returned to the striner housing be pumped over gin; on two pipe systems the internl by p screw is instlled in the internl by pss nd excess oil is turned through the return port to the storge tnk. The top side of the diphrgm S, in the hydrulic oil vlve V, is nected to the by pss chmber. There re two resons for venting diphrgm to the return: 1, to mintin n equl pressure on both s of the diphrgm during shut down, regrdless of the loction of the t 2, to mintin uniform pressure differentil on the diphrgm when burner is in opertion. Oil under pressure in the metering pump hou fills the intke port J, where it is picked up by pistons K, inside pump rotor. As the rotor revolves inside the eccentric ring L, the pist becuse of the eccentric effect between the eccentric ring nd the ro re forced to move in nd out in their respective cylinders in the ro On the out stroke, oil is tken from the inlet port J, into the cylinders in the rotor. On the down stroke of the pistons, metered oil is dischrged into the dischrge port M. The mount of oil tht is picked up by ech stroke of ech piston is determined by the length of the piston stroke. The length of stroke of the piston cn be incresed or decresed by turning the djusting screw N, thereby chnging the reltive position of the eccentric ring to the rotor. Ques. How my the firing rte be incresed or decresed? Ans. By chnging the length of the stroke of the piston. The metered (mesured) oil is delivered through pssge from the dischrge port M, to the hydrulic oil vlve. Ques. In the oil vlve, how is internl ir delivered? Ans. By the pressurotor P. The pressurotor opertes in pproximtely the sme mnner s centrifugl pump. Rotor vnes Q, re held in slots in the rotor P. Centrifugl force of the rotor s it turns holds the vnes out ginst the rotor cylinder. Since the rotor housing nd the rotor re off center to ech other, the vnes re mde to move in nd out of their slots. The movement of the rotor cuses ir to be tken into the housing through the ir intke muffler R. Pressure is built up on the ir in the pressurotor nd the ir is dischrged from the pressurotor on the opposite side from where it ws picked up. Ques. How should the operting pressure be djusted? Ans. It should be djusted to between 13/2 nd 2Y4 lbs. per sq. in. This pressure is djusted by chnging the pressure djusting screw U, in the by pss between the pressure side of the pressurotor nd the inlet.
6F The pressurotor is clened nd lubricted by smll mount of oil proximtely 1 drops per minute) fed to it from the cylinder round hollow stem T of the oil vlve. The internl ir moves long the ir tube to the nole. In the no internl ir nd metered oil re brought into contct with ech ot The ir moving down the ir tube Y, psses round the oil spirl Z, enters the digonl slots. As the ir psses through these three dig slots, it psses over the oil ports, picking up the metered oil. The dig( slots imprt swirling motion to the ir nd oil. The ir nd oil mixi set into this swirling motion inside the nole tip ZZ, is whipped c the knife edge of the nole orifice where sprying is ccomplishe Ques. Wht hppens when the burner shuts off? Ans. The oil pressure from the ger pump E, drops s motor slows down. When the motor slows down to pproximtely 2,1 r.p.m. the r sure drop will be sufficient to permit the spring W to force the piston down on its set VP, thus stopping the flow of metered oil. The vcuum creted in the oil tube X, when the piston PP dc cuses the metered oil in the tube to be held in the tube during shut de Air from the pressurotor tht is delivered through the nole, fter oil vlve is closed, positively purges the oil from the end of the no thus eliminting the crbonition of the oil in the nole by refle het from the combustion chmber fter shut down.