YSAQMD RULE 2.27 INDUST.,INST.,& COMM.BOILERS,STM.GEN.&HTRS               
LAST REVISED 10/27/93
               
               RULE 2.27 INDUSTRIAL, INSTITUTIONAL, AND COMMERCIAL BOILERS,
                            STEAM GENERATORS, AND PROCESS HEATERS

                                  ADOPTED October 27, 1993

                                           INDEX

           100  GENERAL
                      101  PURPOSE
                      102  APPLICABILITY
                      110  EXEMPTION, NONGASEOUS FUELS
                      111  EXEMPTION, ELECTRIC UTILITY BOILERS
                      112  EXEMPTION, WASTE HEAT RECOVERY BOILERS
                      113  EXEMPTION, DRYERS
                      114  EXEMPTION, CEMENT AND LIME KILNS, GLASS MELTING
                           FURNACES, AND SMELTERS

           200  DEFINITIONS
                      201  ANNUAL HEAT INPUT
                      202  BARCT
                      203  BOILER OR STEAM GENERATOR
                      204  BRITISH THERMAL UNIT (BTU)
                      205  GAS
                      206  HEAT INPUT
                      207  HIGHER HEATING VALUE (HHV)
                      208  NOx EMISSIONS (NOx)
                      209  NONGASEOUS FUEL
                      210  PARTS PER MILLION(BY VOLUME) (ppmv)
                      211  PROCESS HEATER
                      212  RATED HEAT INPUT
                      213  STANDARD CONDITIONS
                      214  THERM
                      215  THREE PREVIOUS CALENDAR YEARS
                      216  UNIT

           300  STANDARDS
                      301  ANNUAL HEAT INPUTS  90,000 THERMS
                      302  ANNUAL HEAT INPUTS < 90,000 THERMS
                      303  EQUIPMENT REQUIREMENTS
                      304  ALTERNATE EMISSION CONTROL PLAN

           400  ADMINISTRATIVE REQUIREMENTS
                      401  COMPLIANCE SCHEDULE
                      402  COMPLIANCE DETERMINATION
                      403  TEST REPORTS

           500  MONITORING AND RECORDS
                      501  FUEL USAGE AND OPERATING HOURS
                      502  TEST METHODS
           600  TUNING PROCEDURE
                      601  GENERAL
                      602  PROCEDURES
           
           100  GENERAL

                101   PURPOSE:  To provide a control measure to limit 
                      emissions of NOx from industrial, institutional, and 
                      commercial boilers, steam generators and process heaters  
                      in conformance with BARCT determinations approved by the  
                      California Air Resources Board to meet the requirements  
                      of the California Clean Air Act.

                102   APPLICABILITY:  This rule applies to boilers, steam
                      generators, and process heaters with rated heat inputs  
                      of greater than or equal to 5 million BTU per hour, used 
                      in all industrial, institutional, and commercial 
                      operations.

                110   EXEMPTION, NONGASEOUS FUELS:  Units subject to the
                      requirements of Section 301 of this rule which normally 
                      burn only gas shall comply with a 150 ppmv, or 0.215 
                      pound per million BTU of heat input, NOx emission when  
                      burning nongaseous fuel, if gas is unavailable for 
                      purchase.  This exemption is limited to not more than 
                      168 hours of operation per calendar year, excluding  
                      equipment and emission testing time not exceeding 48 
                      hours per calendar year.

                111   EXEMPTION, ELECTRIC UTILITY BOILERS:  The provisions of 
                      this rule does not apply to boilers used by electric 
                      utilities to generate electricity.

                112   EXEMPTION: WASTE HEAT RECOVERY BOILERS:  The provisions  
                      of this rule do not apply to waste heat recovery boilers 
                      that are used to recover sensible heat from the exhaust  
                      of combustion turbines.

                113   EXEMPTION, DRYERS: The provisions of this rule do not 
                      apply to dryers in which the material being dried is in 
                      direct contact with the products of combustion.

                114   EXEMPTION, CEMENT AND LIME KILNS, GLASS MELTING 
                      FURNACES, AND SMELTERS:  The provisions of this rule do 
                      not apply to cement and lime kilns, glass melting 
                      furnaces and smelters.

           200  DEFINITIONS

                201   ANNUAL HEAT INPUT: The total heat input of fuels burned 
                      by a unit in a calendar year, as determined from the  
                      HHV and cumulative annual usage of each fuel.

                202   BARCT:  "Best Available Retrofit Control Technology"  
                      as defined in section 40406 of the California Health and 
                      Safety Code as "an emission limitation that is based on 
                      the maximum degree of reduction achievable, taking into  
                      account environmental, energy, and economic impacts by 
                      each class or category of source".

                203   BOILER OR STEAM GENERATOR:  Any combustion equipment 
                      fired with any fuel and used to produce steam that is  
                      not used exclusively to produce electricity for sale. 
                      This definition does not include any waste heat recovery 
                      boiler that is used to recover sensible heat from the 
                      exhaust of a combustion turbine.

                204   BRITISH THERMAL UNIT (BTU): The amount of heat required 
                      to raise the temperature of one pound of water from  
                      59oF to 60oF at one atmosphere.

                205   GAS: Any fuel which is a gas at standard conditions

                206   HEAT INPUT:  The chemical heat released due to fuel
                      combustion in a unit, using the higher heating value of 
                      the fuel.  This does not include the sensible heat of  
                      incoming combustion air.

                207   HIGHER HEATING VALUE (HHV): The total heat liberated  
                      per mass of fuel burned (BTU per pound), when fuel and 
                      dry air at standard conditions undergo complete 
                      combustion and all resultant products are brought to 
                      their standard states at standard conditions.  HHV shall 
                      be determined by one of the following test methods:

                      207.1 ASTM D 2015-85 for solid fuels; or

                      207.2 ASTM D 240-87 or ASTM D 2382-82 for liquid 
                            hydrocarbon fuels; or

                      207.3 ASTM D 1826-88 or ASTM D 1945-81 in conjunction  
                            with ASTM D 3588-89 for gaseous fuels.

                208   NOx EMISSIONS (NOx):  The sum of nitric oxides and 
                      nitrogen dioxide in the flue gas.

                209   NONGASEOUS FUEL:  Any fuel which is not a gas at 
                      standard conditions.

                210   PARTS PER MILLION (BY VOLUME) (ppmv):  The ratio of  
                      the number of gas molecules of a given species, or 
                      group, to the number of millions of total gas molecules.

                211   PROCESS HEATER:  Any combustion equipment fired with any
                      fuel, and which transfers heat from combustion gases to
                      water or process streams.  This definition does not 
                      include any dryers in which the material being dried is  
                      in direct contact with the products of combustion, 
                      cement or lime kilns, glass melting furnaces, or 
                      smelters.

                212   RATED HEAT INPUT:  The heat input capacity, in million  
                      BTU per hour, specified on the nameplate of the 
                      combustion unit.  If the combustion unit has been 
                      altered or modified such that its maximum heat input is 
                      different than the heat input capacity specified on the 
                      nameplate, the maximum heat input shall be considered as 
                      the rated heat input.

                213   STANDARD CONDITIONS: 68oF and one atmosphere.

                214   THERM: One hundred thousand (100,000) BTU.

                215   THREE PREVIOUS CALENDAR YEARS: The three consecutive 
                      years immediately preceding the year in which final 
                      compliance is required by this rule, or the three  
                      consecutive years immediately preceding each calendar  
                      year of compliance thereafter.

                216   UNIT:  Any boiler, steam generator or process heater as
                      defined in Sections 203 and 211 of this rule.

           300  STANDARDS

                301   ANNUAL HEAT INPUTS  90,000 THERMS: For units with rated
                      heat inputs of greater than or equal to 5 million BTU 
                      per hour and annual heat inputs of greater than or equal 
                      to 90,000 therms for any three previous calendar years,  
                      NOx emissions shall not exceed the following levels:

                      301.1 30 parts per million by volume (ppmv), or 0.036 
                            pound per million BTU of heat input when operated 
                            on gas; or

                      301.2 40 parts per million by volume (ppmv), or 0.052 
                            pound per million BTU of heat input, when operated  
                            on nongaseous fuel; or

                      301.3 The heat-input weighted average of the limits 
                            specified in 301.1 and 301.2, above, when operated 
                            on combinations of gas and nongaseous fuels.

                            Emissions  from  units subject to  this  Section  
                            shall  not exceed a carbon monoxide  concentration  
                            of  400  parts  per million by volume (ppmv).

                302   ANNUAL  HEAT  INPUTS  < 90,000 THERMS: Units with rated 
                      heat inputs of greater than  of  equal  to 5 million BTU 
                      per hour and annual heat inputs of less than  90,000  
                      therms for each of  the  three previous calendar years 
                      or units  with  rated heat inputs  of  greater  than or 
                      equal to 5 million BTU per hour and not subject to the 
                      provisions of Section 301 shall:

                      302.1 Be operated in a manner that maintains stack-gas 
                            oxygen concentrations at less than or equal to 
                            3.00 percent by volume on a dry basis; or

                      302.2 Be operated with a stack-gas  oxygen trim system 
                            set at 3.00 percent by volume oxygen.  The  
                            tolerance  of this setting shall be plus or minus 
                            () five  percent; or

                      302.3 Be tuned at least once per year by a technician 
                            that is qualified,  to  the  satisfaction  of the 
                            Air Pollution Control  Officer,  to perform a tune
                            -up  in  accordance with Section 600 of this rule; 
                            or

                      302.4 Be operated in compliance  with the applicable 
                            emission levels specified in Section 301 of this 
                            rule.

                303   EQUIPMENT REQUIREMENTS

                      303.1 Owners or operators of units  which simultaneously 
                            fire combinations of different fuels, and are 
                            subject to the requirements of Section 301, shall  
                            install  mass  flow rate   meters   in  each  fuel  
                            line.  Alternatively, volumetric  flow  rate  
                            meters  may   be  installed  in conjunction  with  
                            temperature and pressure  meters  in each fuel 
                            line.

                      303.2 Owners or operators  of units which employ flue-
                            gas NOx reducing technology and  subject to the 
                            requirements of Section  301 of this rule,  shall  
                            install  meters,  as applicable,  to  allow  
                            instantaneous monitoring of the operational  
                            characteristics   of   the  NOx  reduction 
                            equipment.

                304   ALTERNATE EMISSION CONTROL PLAN: The owner  or operator  
                      of any  unit  may  comply  with  Section  301  of  this 
                      Rule by controlling   units   subject  to  this  Rule  
                      at  the  same stationary source which are in existence 
                      or are replacements for units in existence  on  October  
                      27,  1993, to achieve a daily NOx emission factor each 
                      day no lower  than that which would result if each unit 
                      in operation were individually  in compliance  with  
                      Section  301.  The  owner or operator must submit an 
                      alternative Emission Control  Plan  (AECP) that is 
                      enforceable  by  the  Air  Pollution  Control  officer,  
                      and receive written approval of the AECP from the Air  
                      Pollution Control Officer prior to implementation.

                      304.1 The AECP shall:
                            a.   Contain,  as  a  minimum, all data, records,
                                 and other information necessary to determine
                                 eligibility  of the  units  for  alternative
                                 emission control, including, but not limited
                                 to:
                                 1)    A list of units subject to alternative
                                       emission control;
                                 2)    Daily average  and  maximum  hours  of
                                       utilization for applicable units;
                                 3)    Rated capacity of each applicable unit
                                       and;
                                 4)    Emissions  limitations  to be included
                                       on Permits to Operate for each unit in
                                       the  AECP  expressed  as  an  emission
                                       factor  in pounds NOx per million  BTU
                                       of heat input.
                            b.   Present  the methodology  for  recordkeeping
                                 and reporting required by Sections 304.4 and
                                 304.5 of this Rule.
                            c.   Demonstrate   that   the   overall   average
                                 emission factor from all operating units  in
                                 the  AECP  will  meet  the  requirements  of
                                 Section 301 on each day.

                      304.2 A  revised  AECP  may  be  submitted  by  the  
                            owner or operator,  along with any required permit 
                            applications, provided that  such  a  revised  
                            plan  adheres  to  the emissions  limits  and  
                            final  compliance dates of this Rule.

                      304.3 a.    NOx   emissions limitations and compliance
                                  determinations  shall be in terms of  pounds  
                                  NO2 per million BTU heat input.
                            b.    Compliance  with  NOx  and  carbon  monoxide
                                  requirements  shall  be determined according
                                  to procedures and test  methods specified in
                                  Section 502 of this Rule.
                            c.    Each  unit  shall  be  tested  to  determine
                                  compliance with the applicable  requirements
                                  of  Sections  304 and 304.1.c not less  than
                                  once every 12 months.
                            d.    All  emissions measurements  shall  be  made
                                  with  the   unit   operating  at  conditions
                                  representative of normal  operations  and at
                                  the  maximum  attainable firing rate allowed
                                  by  District  permit.  No  determination  of
                                  compliance  with   the  requirements  of  an
                                  approved AECP shall  be  established  within
                                  two hours after a continuous period in which
                                  fuel  flow  to  the  unit is shut off for 30
                                  minutes or longer.

                      304.4 a.    Records  shall  be maintained  for  two  
                                  calendar years and shall be  made  available  
                                  to  the  Air Pollution Control officer upon 
                                  request.
                            b.    The  owner  or  operator  shall maintain the
                                  following records  for each unit included in
                                  the AECP:
                                  1)    Fuel type and amount for each unit for
                                        each day;
                                  2)    Permitted emissions  factors  for each
                                        unit for each day;
                                  3)    The emissions from each unit for  each
                                        day;
                                  4)    The  total  emissions for all units in
                                        operation in each day and;
                                  5)    The  overall average  emission  factor
                                        for all  units  in  operation  on each
                                        day.

                      304.5 No later than 30 days after the end of each month,  
                            the owner  or  operator  of  any units included in 
                            the AECP shall submit:
                            a.   The  total daily  emissions  for  each  fuel
                                 type;
                            b.   The total  daily  million  BTU  combusted of
                                 each fuel type;
                            c.   The daily overall average pounds  of NOx per
                                 million BTU for all units in operation which
                                 would result if each unit were individual in
                                 compliance with Section 301 and;
                            d.   The daily overall average pounds of  NOx per
                                 million  BTU  for all units in operation  on
                                 each day.
                           
                      305.6 If on any day the emission factor calculated in 
                            Section 304.5.d  exceeds  the  emission  factor  
                            calculated  in Section  304.5.c, the excess 
                            emissions shall be considered a violation of this 
                            Rule.

           400  ADMINISTRATIVE REQUIREMENTS

                401   COMPLIANCE  SCHEDULE: The owner or operator of units 
                      subject to this rule  shall  fulfill  the  following  
                      increments  of progress:

                      401.1 Submit,  by  October  27,  1995,  a plan 
                            containing the following:
                            a.   A list of all units with  their  rated  heat
                                 inputs and anticipated annual heat inputs.
                            b.   For owners or operators of units subject  to
                                 section  301,  for  each  unit  listed,  the
                                 selected  method of achieving the applicable
                                 standard or standards of Section 301.
                            c.   For owners  or operators of units subject to
                                 Section  302,   for   each  unit  listed,  a
                                 selection  of  one  of  the   four   options
                                 specified   in   Section   302   to  achieve
                                 compliance with this rule.
                              
                      401.2 All  owners  or operators subject to the 
                            provisions of this rule shall  submit an 
                            application for Authority to Construct for any  
                            modifications required  to  achieve compliance 
                            with the requirements of this rule no  later 
                            than October 27, 1995.

                      401.3 By  October 27, 1997, demonstrate final compliance 
                            with all applicable standards and requirements of 
                            this rule.

                402   COMPLIANCE DETERMINATION:

                      402.1 An owner  or  operator  of  any  unit(s) shall 
                            have the option of complying with either the 
                            pounds-per-million-BTU  emission  rates or the 
                            parts-per-million-by-volume emission limits 
                            specified in Section 301.

                      402.2 All emission determinations  shall  be  made in 
                            the as-found   operating   condition,   except  
                            that  emission determinations shall include at a  
                            minimum at least one source  test  conducted  at  
                            the  maximum  firing  rate allowed  by  the  
                            District  permit, and  no  compliance 
                            determination  shall be established  within  two  
                            hours after a continuous  period  in  which  fuel 
                            flow to the unit  is  zero,  or  shut  off,  for 
                            thirty minutes  or longer.

                      402.3 All ppmv emission limits specified  in Sections 
                            110 and 301 are referenced at dry stack-gas 
                            conditions and 3.00 percent    by   volume   
                            stack-gas   oxygen.   Emission concentrations  
                            shall  be  corrected  to  3.00  percent oxygen as 
                            follows:

                [ppm  NOx]corrected  =20.95%  -  3.00%  * [ppm NOx]measured
                                      -----------------      
                                      20.95% - [% O2]measured

                [ppm  CO]corrected   =20.95%  -  3.00%  * [ppm CO]measured
                                      -----------------           
                                      20.95% - [% O2]measured

                      402.4 All  pounds-per-million-BTU  emission  rates  
                            shall  be calculated  as  pounds  of  nitrogen  
                            dioxide (NO2) per million BTU of heat input.

                      402.5 All emission concentrations and emission rates 
                            shall be based on 15-consecutive-minute averages. 
                            These averages shall be calculated from no less 
                            than five  data  sets, recorded from samplings on 
                            intervals of no greater than three minutes.

                      402.6 All  units  covered  under  Sections  301 and 302 
                            shall conduct source tests to demonstrate initial  
                            compliance with  the  requirements  of  these 
                            Sections. Additional source testing may be 
                            required  by  the  Air  Pollution Control Officer 
                            as necessary to ensure compliance  with the 
                            standards set forth in Sections 301 and 302 of 
                            this Rule.  Units covered under Section 302.3 
                            shall be tuned not less than once every 12 months.


                      402.7 A violation  of  the  plan  under  Section  401.1 
                            shall constitute a violation of this rule.

                      402.8 The  cumulative  annual  usage  of  each fuel 
                            shall  be monitored  from  utility service meters,  
                            purchase,  or tank fill records,  or  by any other 
                            acceptable methods approved by the Air Pollution 
                            Control Officer.
                            
                403   TEST REPORTS: The owners or operators  of  units  
                      subject to Section  300  of  this  rule  shall  submit  
                      compliance test reports  on  each  unit for each fuel 
                      burned, including  any fuels which may be burned  in  
                      accordance  with Section 110, not less than once every 
                      twelve months; except  that tune-up verification reports 
                      shall be submitted not less  than  once every  twelve  
                      months  for  each unit complying with Section 302.3 for 
                      each fuel burned. Test  reports  shall include the 
                      operational  characteristics of all flue-gas  NOx  
                      reduction equipment. The  first  test or tune-up report, 
                      for each unit subject to Section 300 of  this  rule  
                      shall be submitted by October 27, 1997.

           500  MONITORING AND RECORDS

                501   FUEL USAGE AND OPERATING HOURS: The owners  or operators 
                      of units subject to Section 300 of this rule shall 
                      monitor  and record  for each unit the HHV and 
                      cumulative annual usage of each fuel.  The  owners  and  
                      operators of units exempt from Section 301 in accordance 
                      with Section 110 shall monitor and record for each unit 
                      the cumulative  hours  of  operation on each  nongaseous  
                      fuel. The records shall be updated  weekly and made 
                      available  to the District upon request. Historical 
                      annual data for the three  previous  calendar years 
                      shall be kept and made available by the owners and 
                      operators.

                502   TEST METHODS:

                      502.1 Compliance  with  NOx  emission  requirements  
                            and  the stack-gas  carbon monoxide and oxygen  
                            requirements  of Section 300  shall  be  
                            determined  using the following test methods:
                            a.   Oxides of Nitrogen - ARB Method 100.
                            b.   Carbon Monoxide - ARB Method 100.
                            c.   Stack-Gas Oxygen - ARB Method 100.
                            d.   NOx Emission Rate (Heat Input  Basis)  - EPA
                                 Method 19.

                      502.2 Integrated  sampling  methods  for  oxides of 
                            nitrogen, stack-gas  oxygen,  and stack-gas 
                            carbon  monoxide,  as approved by the Air 
                            Pollution  Control  Officer, may be acceptable  
                            for  determination of compliance  with  NOx
                            emission concentration or rate limits.

           600  TUNING PROCEDURE

                601   GENERAL:  Nothing  in  this   tuning   procedure1  
                      shall  be construed to require any act or omission  
                      that  would result in  unsafe  conditions  or  would  
                      be  in  violation of  any regulation  or  requirement  
                      established by Factory  Mutual, Industrial   Risk   
                      Insurors,   National   Fire   Prevention Association,   
                      the  California  Department   of   Industrial Relations 
                      (Occupational  Safety  and  Health  Division), the 
                      Federal  Occupational  Safety and Health Administration,  
                      or other relevant regulations and requirements.

                602   PROCEDURES:

                      601.1 Operate the unit at  the  firing  rate  most 
                            typical of normal  operation. If the unit 
                            experiences  significant load variations  during  
                            normal operations, operate the unit at its 
                            average firing rate.

                      601.2 At the firing rate established in Section 601.1, 
                            record stack-gas temperatures, oxygen  
                            concentration,  and  CO concentration (for gaseous 
                            fuels) or smoke-spot number2 (for  liquid fuels), 
                            and observe flame conditions after unit operation  
                            stabilizes at the selected firing rate.  If the 
                            excess oxygen  in  the stack-gas is at the lower
                            range of typical minimum values3,  and  if CO 
                            emissions are  low  and  there is no smoke, the 
                            unit is  probably operating  at  near   optimum   
                            efficiency  -  at  this particular firing rate. 
                            However, complete the remaining portion  of this 
                            procedure to determine  whether  still lower 
                            oxygen levels are practical.

                      602.3 Increase combustion air flow until the stack-gas 
                            oxygen levels increase  by  one  or two percent 
                            over the level measured in Section 602.2.
                            As  in  Section  602.2,   record   the  stack-gas
                            temperature, CO concentration (for gaseous fuels)
                            or  smoke-spot  number  (for  liquid fuels),  and
                            observe flame conditions for these  higher oxygen
                            levels after unit operation stabilizes.


           -----------------------------------------------------------------
           1.   This tuning procedure is based on a tune-up procedure 
                developed by KVB, Inc. for the EPA.
           2.   The smoke-spot number can be determined with ASTM  test  
                method D-2156  or  with  the  Bacharach  method.  The  
                Bacharach  method is included in a tune-up kit that can be 
                purchased from the Bacharach Company.
           3.   Typical minimum oxygen levels for units at high firing rates 
                are:
                a.    For natural gas: 0.5 - 3%
                b.    For liquid fuels: 2 - 4%.


                      602.4 Decrease combustion air flow until the stack-gas 
                            oxygen is  at  the level measured in Section 
                            602.2. From  this level gradually  reduce  the  
                            combustion  air  flow, in small  increments.  
                            After  each  increment,  record the stack-gas   
                            temperature,   oxygen   concentration,   CO 
                            concentration   (for  gaseous  fuels),  and  
                            smoke-spot number (for liquid  fuels). Also, 
                            observe the flame and record any changes in its 
                            condition.

                      602.5 Continue to reduce combustion  air flow stepwise, 
                            until one of the following limits is reached:
                            a.   Unacceptable  flame  conditions  -  such  as
                                 flame impingement on furnace walls or burner
                                 parts, excessive flame  carryover,  or flame
                                 instability;
                            b.   Stack-gas CO concentrations greater than 400
                                 ppm;
                            c.   Smoking at stack;
                            d.   Equipment-related limitations - such  as low
                                 windbox/furnace    pressure    differential,
                                 built-in air-flow limits, etc.

                      602.6 Develop an O2/CO curve (for gaseous fuels)  or 
                            O2/smoke curve  (for  liquid  fuels)  similar to 
                            those shown  in Figures  1  and 2 using the 
                            excess  oxygen  and  CO  or smoke-spot number  
                            data obtained at each combustion air flow setting.

                      

                           NOTE:  For fax copies of the following two figures, 
                                  please contact the district directly.


                                          Figure 1

                               Oxygen/CO Characteristic Curve





                      





                                          Figure 2

                             Oxygen/Smoke Characteristic Curve




                                                        
                                                        Source: KVB Inc.
                      

                      
                      602.7 From the curves prepares  in  Section  602.6,  
                            find the stack-gas  oxygen  levels  where  the  
                            CO  emissions or smoke-spot number equal the 
                            following values:

                      -----------------------------------------------------
                     |      Fuel      |      Measurement      |   Value    |
                     |----------------|-----------------------|------------|
                     |    Gaseous     |      CO Emissions     |  400 PPM   |
                     |----------------|-----------------------|------------|
                     |  #1 & #2 Oils  |   Smoke Spot Number   |  Number 1  |
                     |----------------|-----------------------|------------|
                     |     #4 Oil     |   Smoke Spot Number   |  Number 2  |
                     |----------------|-----------------------|------------|
                     |     #5 Oil     |   Smoke Spot Number   |  Number 3  |
                     |----------------|-----------------------|------------|
                     |   Other Oils   |   Smoke Spot Number   |  Number 4  |
                      -----------------------------------------------------

                             The above conditions are referred to as the CO or
                             smoke-spot  thresholds, or as the minimum  excess
                             oxygen levels.  Compare  this  minimum  value  of
                             excess  oxygen  to the expected value provided by
                             the combustion unit  manufacturer. If the minimum
                             level  found  is substantially  higher  than  the
                             value  provided   by   the  manufacturer,  burner
                             adjustments can probably  be made to improve fuel
                             and  air  mix, thereby allowing  operations  with
                             less air.

                      602.8 Add 0.5 to 2.0 percent  to  the  minimum  excess 
                            oxygen level found in Section 602.7 and reset 
                            burner  controls to  operate  automatically  at  
                            this  higher  stack-gas oxygen  level.  This  
                            margin  above  the minimum oxygen level  accounts  
                            for  fuel  variations,  variations  in atmospheric     
                            conditions,     load    changes,    and 
                            nonrepeatability or play in automatic controls.

                      602.9 If the load of the combustion unit varies 
                            significantly during  normal  operation, repeat 
                            Sections  602.1-602.8 for the firing rates that 
                            represent the upper and lower limits  of  the 
                            range  of  the  load.  Because  control 
                            adjustments at one firing rate may affect 
                            conditions at other firing rates, it may not be 
                            possible to establish the optimum excess oxygen 
                            level at all firing rates. If this is the case,  
                            choose  the  burner control settings that give 
                            the best performance over  the  range  of the
                            firing  rates.  If  one  firing  rate 
                            predominates, the setting should optimize the 
                            conditions at the rate.
                            
                      602.10Verify  that  the  new  settings can  accommodate  
                            the sudden load changes that may  occur  in daily 
                            operation without  adverse  effects.  Do  this by 
                            increasing  and decreasing load rapidly while 
                            observing  the  flame and stack.  If  any  of the  
                            conditions  in  Section 602.5 result,  reset  the  
                            combustion  controls to provide  a slightly higher 
                            level of excess oxygen  at the affected firing  
                            rates.  Next,  verify these new settings  in  a 
                            similar fashion. Then make  sure that the final 
                            control settings   are   recorded  at  steady-
                            state   operating conditions for future reference.