KERAPCD RULE 427 STATIONARY PISTION ENGINES (NOx)
LAST REVISED 01/25/96



RULE 427 Stationary Piston Engines (Oxides of Nitrogen) - Adopted 6/1/87, Amended 10/13/94, 1/25/96

I. Purpose

The purpose of this Rule is to limit oxides of nitrogen (NOx) emissions from existing stationary piston engines to levels consistent with Reasonably Available Control Technology (RACT) to satisfy California Health & Safety Code, Section 40918 (b) and 1990 Federal Clean Air Act Amendments, Section 182(f). Carbon monoxide emissions are also limited to insure maintenance of efficient combustion at reduced NOx levels.

II. Applicability

This Rule shall apply, as specified, to all rich-burn, lean-burn, and diesel engines of more than 50 rated brake horsepower.

III. Definitions

For purposes of this Rule, the following definitions shall apply:

A. Cyclicly-Loaded Engine - any engine experiencing under normal operating conditions variation in shaft load by 40 percent or more of rated brake horsepower during recurrent periods of 30 seconds or less.

B. Diesel Engine - any compression-ignited engine fueled with diesel oil, or combination of diesel oil and gaseous fuel.

C. Emergency Standby Engine - any engine used as a temporary replacement for primary mechanical or electrical power sources during periods of fuel or energy shortage or while primary power source is under repair.

D. Gaseous Fuel - any fuel existing as gas at standard conditions, including, but not limited to: natural gas, methane, ethane, propane, butane, and liquified petroleum gas (LPG).

E. Higher Heating Value (HHV) - total heat released per mass of fuel burned (Btu's per pound), when fuel and dry air at standard conditions undergo complete combustion and all resulting products are brought to standard conditions.

F. Lean-Burn Engine - any spark-ignited, Otto cycle or two stroke engine fueled with gaseous or liquid fuel and operated with an exhaust gas oxygen concentration of 4 percent by volume, or greater.



G. Oxides of Nitrogen (NOx) - total nitrogen oxides expressed as NO2.

H. Rated Brake Horsepower (bhp) - maximum continuous service rating specified for engine by manufacturer and listed on nameplate of unit.

I. Reasonably Available Control Technology (RACT) - lowest emission limitation a particular source is capable of meeting by application of control technology reasonably available considering technological and economic feasibility.

J. Rich-Burn Engine - any spark-ignited, Otto cycle or two stroke engine fueled with gaseous or liquid fuel and operated with an exhaust gas oxygen concentration of less than 4 percent by volume.

K. Shaft Output - actual engine work done (brake horsepower-hours) calculated from measurements and data derived from operating parameters and/or performance curve(s) of device being powered by engine.

L. Site - any specific location within a facility, for example, a building.

M. Stationary Piston Engine (engine) - any spark or compression-ignited reciprocating internal combustion engine attached to a foundation at a site or portable and operated at the same site for more than one year.

IV. Exemptions

This Rule shall not apply to:

A. Engines used exclusively for agricultural operations necessary for growing of crops or raising of fowl or animals;

B. Emergency standby engines, operating less than 200 hours per year as documented by an elapsed operating time meter;

C. Engines used exclusively for firefighting purposes or flood control;

D. Laboratory engines used in research and testing;

E. Engines operated exclusively for purposes of performance verification and testing; or

F. Portable engines not operated at the same site for more than one year.







V. Requirements for Engines Greater Than 50 bhp

An owner/operator of any engine subject to this Section shall service such engine in accordance with following NOx minimization maintenance schedule:

A. Lubricating Oil and Filter (if so equipped): Change once every three months or after no more than 300 hours of operation.

B. Inlet Air Filter: Clean once every three months or after no more than 300 hours of operation; replace (if cartridge type) once every 1000 hours of operation.

C. Fuel Filter: Clean once every year or replace (if cartridge type) once every 1000 hours of operation.

D. Intake and Exhaust Valves (if so equipped and adjustable), Spark Plugs (if so equipped), Spark Timing and Dwell or Fuel Injection Timing (if adjustable), and Carburetor Mixture (if adjustable): Check and adjust (if necessary) to factory specifications once every year or after no more than 1000 hours of operation.

E. Spark Plugs and Ignition Points (if so equipped): Replace after 3000 hours of operation.

F. Coolant (if so equipped): Change once every year.

G. Exhaust System: Check for leaks and/or restrictions once every year.

VI. Requirements for Engines 250 bhp or More

An owner/operator or any engine subject to this Section shall comply with following NOx reduction requirements or emission limits as applicable.

A. Rich-Burn Engine:

1. Exhaust gas oxides of nitrogen concentration, averaged over not less than 15 consecutive minutes:

a. Shall be reduced by 90 percent across any exhaust gas control device; or

b. Shall not exceed 50 ppm by volume on dry basis corrected to 15 percent oxygen.

2. Exhaust gas carbon monoxide concentration averaged over not less than 15 consecutive minutes shall not exceed 2,000 ppm by volume on dry basis corrected to 15 percent oxygen.

B. Lean-Burn Engine:

1. Exhaust gas oxides of nitrogen concentration averaged over not less than 15 consecutive minutes:

a. Shall be reduced by at least 80 percent across any exhaust gas control device; or

b. Shall not exceed 125 ppm by volume on dry basis corrected to 15 percent oxygen; or

2. For lean burn engines controlled exclusively by combustion modifications, exhaust gas oxides of nitrogen concentration shall not exceed 2.0 grams per brake horsepower hour of output, or where engine has no means to measure shaft output, exhaust gas oxides of nitrogen concentration, averaged over not less than 15 consecutive minutes, shall not exceed 125 ppm by volume on dry basis corrected to 15 percent oxygen.

3. Exhaust gas carbon monoxide concentration averaged over not less than 15 consecutive minutes shall not exceed 2,000 ppm by volume on dry basis corrected to 15 percent oxygen.

C. Diesel Engine:

Exhaust gas oxides of nitrogen concentration averaged over not less than 15 consecutive minutes:

1. Shall be reduced by at least 30 percent across any exhaust gas control device; or

2. Shall not exceed 600 ppm by volume on dry basis corrected to 15 percent oxygen.

3. Exhaust gas carbon monoxide concentration averaged over not less than 15 consecutive minutes shall not exceed 2,000 ppm by volume on dry basis corrected to 15 percent oxygen.

D. Thermal Efficiency Adjustment:

For any engine subject to this Section with demonstrated thermal efficiency greater than 30%, the following procedure may be used to determine allowable emission limits. Each emission limit in Subsection A., B., or C., may be multiplied by engine thermal efficiency and divided by reference efficiency of 30 percent. Engine efficiency (E) shall be determined using one of following two methods, whichever is lower:

1. E= (3413 Btu/bhp-hr) (100)

Actual Heat Rate at HHV of fuel (Btu/bhp-hr)

Where demonstrated percent E applies to engine only, without consideration of any downstream energy recovery, and is averaged over not less than 15 consecutive minutes and measured within 30 days of first emissions compliance test; or

2. E= (Manufacturer's Rated Efficiency [Continuous] at LHV)(LHV)

(HHV)

Engine with less than 30 percent efficiency, shall be assigned an efficiency of 30 percent for purposes of this Rule.

VII. Monitoring

An owner/operator of any engine subject to Section VI. of this Rule shall:

A. Install, operate, and maintain automatic combustion controls to ensure on-going compliance with applicable emission limit; or

B. Install, operate, and maintain analytical equipment and/or procedures or sensing devices, indicating:

1. For Rich-Burn Engine:

a. Exhaust gas oxides of nitrogen and carbon monoxide concentrations, or

b. For a catalyst system, air to fuel ratio showing operation within limits as recommended by catalyst system manufacturer.

2. For Lean-Burn or Diesel Engine:

a. Exhaust gas oxides of nitrogen and carbon monoxide concentrations, and

b. Flow rate of any reducing liquids or gases added to exhaust gases for operation of catalyst system.

VIII.. Administrative Requirements

A. Emission Control Plan

An owner/operator of any engine subject to Section V. or VI. shall submit to Control Officer, for his approval, a Control Plan. Such Control Plan shall include for each facility:

1. List of all engines subject to Rule, including type of engine service and KCAPCD Permit number;

2. Engine manufacturer, model number, rated brake horsepower, type of fuel (liquid and/or gas), and type of ignition (compression or spark);

3. Description of actions to be taken or emission controls to be applied to each engine;

4. For any engine subject to Section VI. and for which the owner/operator chooses to comply with control efficiency limits, baseline NOx test data. Such data shall represent emissions during maximum normal operating conditions; and

5. Emission control equipment construction schedule, if applicable.

B. Recordkeeping

1. An owner/operator of any engine subject to Section V. of this Rule shall maintain an engine service log for each engine demonstrating compliance with Section V., for at least two years, and make such log readily available to District personnel.

2. An owner/operator of any engine subject to Section VI. of this Rule shall maintain an engine operating log, including on monthly basis total hours of operation, type and quantity of fuel used and cumulative hours of operation since last source test required by Subsection C., below. This information shall be maintained for period of two years and made readily available to District personnel.

C. Compliance Testing

An owner/operator of any engine subject to Section VI. of this Rule shall demonstrate compliance with applicable requirements at least once every calendar year.

IX. Test Methods

Compliance with requirements of Section VI. shall be determined in accordance with following test procedures:

A. Oxides of nitrogen - EPA Method 7E, or CARB Method 100.

B. Carbon monoxide - EPA Method 10, or CARB Method 100.

C. Stack gas oxygen - EPA Method 3 or 3A, or CARB Method 100.

X. Compliance Schedules

A. An owner/operator of any engine subject to Section V. of this Rule shall comply with the following schedule:

1. By January 1, 1995, submit emission control plan pursuant to Section VIII.

2. By May 31, 1995, comply with Section V.

B. An owner/operator of any engine subject to Section VI. of this Rule shall comply with following schedule:

1. By June 1, 1996, submit Emission Control Plan pursuant to Section VIII.

2. At least 8 months prior to compliance date for any affected engine, submit application for Authority to Construct, including signed contract for any necessary emission control equipment.

3. At least 2 months prior to compliance date for any affected engine, initiate installation of any necessary control equipment.

4. By June 1, 1997 comply with applicable requirements of Section VI. except for cyclicly-loaded engines which shall comply by January 1, 1998 and public water district engines which shall comply by May 31, 1999.

Engines subject to Section VI. are not subject to Section V. after the applicable Subsection X.B.4. compliance date.