Catalyst Installation General Requirements for CG137-12 and G3300B Engines{1091} Caterpillar

Engine:

CG137-12 (S/N: WRX1-UP)

G3304B (S/N: A4E1-UP)

G3306B (S/N: R6S1-UP)

Introduction

This Special Instruction describes the general requirements to install the catalyst for CG137-12 and G3300B Natural Gas Engines.

The aftertreatment is a three-way catalyst for stoichiometric engines. This catalyst reduces the nitrogen oxides (NO_x), carbon monoxide (CO), and hydrocarbons (HC), from engine exhaust. The catalyst is defined by the needed space, velocity, and exhaust emissions for each engine platform and horsepower rating. Attention must be given to any exhaust gas flow restriction. Stringent requirements on stationary gas engine noise limits may require more restrictive exhaust systems.

Do not perform any procedure in this Special Instruction until you read this information and you understand this information.

G3300B Series Engines

Illustration 1	g02444479
Typical G3300B installation (1) Exhaust elbow (2) Pipe (3) Exhaust flange (4) Muffler (5) Rain cap (6) Engine exhaust outlet (7) Engine flexible fitting (8) Gasket (9) Catalyst (10) Flange (11) Coupling

Parts List

Note: All serviceable components of the Cat three-way catalyst and converter are available through the parts distribution network.

0.5g NO_x Catalyst Systems

1.0g NO_x Catalyst Systems

Catalyst Installation General Requirements

Proper installation of the catalytic converter is essential to ensure the required performance and life of the emissions solution. To meet the required performance, the pipe length between the engine exhaust outlet and the converter is critical. Refer to ""Location/Setback Distance" " for specific requirements.

The catalyst skin temperature and the exhaust gas temperature can be difficult to measure and/or simulate. The temperatures are dependant upon many factors including the following:

• The nature of the engine/aftertreatment ambient operating conditions

• The design of the exhaust piping including the aftertreatment

• The engine speed/load conditions

• The condition of the catalyst

Ensure that the aftertreatment device is not mounted close to surrounding components that may be damaged by heat.

Exhaust System Requirements

Note: Any exhaust system attachments that may result in plugging, fouling, or other damage to the catalyst are not permitted.

The exhaust system upstream of the catalyst must be designed leak free. A leak upstream of the catalyst may directly affect the O₂ storage of the catalyst. Exhaust leaks also affects the ability to a convert exhaust gas constituents to the required outputs.

Location/Setback Distance

The catalyst is close coupled to the exhaust elbow. Use the 359-4330 Bellows As for a normally aspirated engine and 359-9170 Bellows As for a turbocharged engine. If, the recommended bellows are not used, then use a similar flexible connection and piping solution. The similar bellows must be 406 mm (16 inch) from the top flange of the O₂ sensor ring to the inlet flange of the catalytic converter.

Mount the catalytic converter as close to the engine out exhaust elbow as possible. Mounting the converter close to the engine increases the inlet exhaust temperatures to the catalyst resulting in greater catalytic conversion efficiency. If, the catalyst must be mounted further away from the engine, ensure that the exhaust inlet temperature to the catalyst is above 400° C (752° F) in all operating conditions. Be sure to consider the effects of cold ambient temperatures and convection when designing the exhaust piping solution for the package. The greatest distance from the exhaust elbow that can be used is dictated by the length of the Caterpillar supplied catalyst harness. Any modification or change in the length of this harness will void all catalyst warranty and may result in emissions non-compliance.

Rotate the converter so the outlet O₂ sensor is in the 3 o'clock position or the 9 o'clock position when mounting horizontally. Rotating the converter will orient the O₂ sensor and the exhaust temperature thermocouples at the correct location for vibration and thermal protection. Reference drawing 381-9149 for suggested sensor and harness attachment.

Flexible Connections

The exhaust piping must allow for movement and thermal expansion so that undue stresses are not imposed on the turbocharger structure or exhaust manifold. Never allow the engine exhaust elbow to support any external loads from any of the exhaust system components. At least one flexible joint or bellows must be installed between the engine exhaust elbow and the catalyst. Flexible connections are needed to isolate engine movement and vibration and to offset piping expansion and contraction.

Piping Considerations

Avoid cantilevering loads off the end of the catalytic converter assembly. Be sure to consider the loads imposed to the catalytic converter from vertical exhaust stacks and exit piping. Never place more than 68 kg (150 lb) of unsupported piping or silencing equipment directly on the converter flanges. Anchor piping on one side of the converter only. Allow one side of the aftertreatment system room for thermal expansion. When lifting the catalytic converter, only use the ANSI flanges. The flanges are the only structural components of the converter body.

Exhaust Backpressure

Backpressure effects the response of the engine to load changes, exhaust temperatures, and fuel consumption. Exhaust systems must be designed to provide the best compromise between noise and backpressure.

The total exhaust backpressure of the G3300B packaged solution must not exceed the following:

• 6.75 kPa (0.98 psi) for turbocharged engines

• 3.00 KPA3.0 kPa (0.44 psi) for naturally aspirated engines

Backpressure of 2.10 kPa (0.30 psi) must be reserved for the catalyst on turbocharged engines, and 0.9 KPA on naturally aspirated engines.

Calculate exhaust system backpressure before finalizing the piping design. Estimate the piping backpressure with the following equations.

Illustration 2	g03403482
kPa equation

Illustration 3	g03403493
psi equation

Where:

• P = Pressure drop (backpressure) measured in kPa and inches of water

• psi = 0.0361 x in. of water column

• kPa = 0.00981 x mm water column

• L = Total equivalent length of pipe in feet or meters

• Q = Exhaust gas flow in cubic feet per minute or cubic meter per minute at rated conditions

• D = Inside diameter of pipe in inches or millimeter

• S = Density of gas in pounds per cubic feet or kilogram per cubic meter

• Ps = Pressure drop of silencer or rain cap measured in kPa or inches of water

Useful conversion factors:

• psi = 0.0361 x inch of water column

• psi = 0.00142 x millimeter of water column

• psi = 0.491 x inch of mercury column

• kPa = 0.0098 x millimeter of water column

• kPa = 0.25 x inch of water

• kPa = 3.386 x inch of mercury column

• kPa = 0.145 psi

Use the following equations to determine values of straight pipe equivalent length for smooth elbows

Illustration 4	g03403544
Standard elbow

Illustration 5	g03403546
Long sweep elbow

Illustration 6	g03403552
45 degree elbow

Illustration 7	g03403597
Square elbow

Where X = 1000 mm or 12 inch

As shown by the equations, if 90 degree elbows are required, long radius elbows with a radius of 1.5 times the pipe diameter helps to lower resistance.

Catalyst Air Fuel Ratio Control Sensors and Wiring

Illustration 8	g02446436
Recommended harness securement location Recommended vibration analysis points (1) Sensor support (2) Recommended vibration analysis point (3) Catalyst sensor harness

The air fuel ratio control is tuned to maintain emissions compliance at or below 0.5g NO_x and 1g NO_x levels. The NO ^xlevels depend on the catalyst used. Care must be taken to ensure that the catalyst sensors and electronics are not exposed to extreme temperatures and vibrations. Keep the sensor harnesses and connectors 76.2 mm (3 inch) away from any portion of the exhaust piping or catalytic converter.

Do not expose the catalyst harness to temperatures above 160 degrees C. Harness life is typically proportional to temperature. The lower the temperature, the longer the life of the harness. Normal techniques such as wire ties and ladder clips can be used to secure this harness to the package structure or exhaust stack, if required. If vinyl coated ladder clips are used to secure this harness, install the vinyl coated ladder clips in areas that are less than 80° C (176.0° F).

Mounting Restrictions

Structural mounting to the converter body of the catalyst is not permitted. Provide structural support for the catalyst by either the top or the bottom flange of the converter or the exhaust piping. Separately support the catalyst and exhaust piping by the package structure. Do not use the engine exhaust outlet to support the aftertreatment system. Improper mounting can introduce unwanted vibration to the catalyst. Improper mounting can be harmful to the catalyst substrate as well as converter body structure.

Structural mounting to the catalytic converter should be provided by either of the ANSI flanges, or the exhaust piping. Mounting on the flanges will allow thermal expansion of the converter body.

Do not expose the catalyst to vibration levels above 1.67 Grms at any load or operating condition. Measure at the upper and lower most securement point for the catalyst thermocouple harnesses. Use the 221-2370 Analyzer Gp , or equivalent. Obtain measurements 254 mm (10 inch) away from the centerline of the catalyst. Use the recommended vibration analysis points (2) to gather accurate data. Refer to Illustration 8.

CG-137-12 Engines

Illustration 9	g03139499
(1) Engine exhaust outlet (2) Engine flexible fitting (3) Flange (4) Elbow, standard only (5) Inline flexible fitting (6) Muffler (7) Flange (8) Catalyst (9) Pipe, standard, or metric (10) Coupling, permits rotation (11) Flange

Parts List

Catalyst Installation General Requirements

Proper installation of the catalytic converter is essential to ensure the required performance and life of the emissions solution. To meet the required performance, the pipe length between the engine exhaust outlet and the converter is critical. Refer to ""Location/Setback Distance" " for specific requirements.

The catalyst skin temperature and the exhaust gas temperature can be difficult to measure and/or simulate. The temperatures are dependant upon many factors including the following:

• The nature of the engine/aftertreatment ambient operating conditions

• The design of the exhaust piping including the aftertreatment

• The engine speed/load conditions

• The condition of the catalyst

Ensure that the aftertreatment device is not mounted close to surrounding components that may be damaged by heat.

Exhaust System Requirements

Note: Any exhaust system attachments that may result in plugging, fouling, or other damage to the catalyst are not permitted.

Note: Any converter or stack mounted vertically must be protected from external water entering the system.

The exhaust system upstream of the catalyst must be designed leak free. A leak upstream of the catalyst may directly affect the O₂ storage of the catalyst. Exhaust leaks also affects the ability to a convert exhaust gas constituents to the required outputs.

Location/Setback Distance

Mount the catalytic converter as close to the engine outlet exhaust elbow as possible. Mounting the converter close to the engine increases the inlet exhaust temperatures to the catalyst resulting in greater catalytic conversion efficiency. If, the catalyst must be mounted further away from the engine, a piping solution will need to be developed to ensure that inlet exhaust temperatures to the catalyst are above 400° C (752° F) in all operating conditions. Be sure to consider the effects of cold ambient temperatures and convection when designing the exhaust piping solution for the package. The greatest distance from the exhaust elbow that can be used is dictated by the length of the Caterpillar supplied catalyst harness. Any modification or change in the length of this harness will void all catalyst warranty and may result in emissions non-compliance.

Rotate the converter so the outlet O₂ sensor is in the3 o'clock position or the 9 o'clock position when mounting in the horizontally. Rotating the converter will orient the O₂ sensor and the exhaust temperature thermocouples at the correct location for vibration and thermal protection. Reference drawing 381-9149 for suggested sensor and harness attachment.

Flexible Connections

The exhaust piping must allow for movement and thermal expansion so that undue stresses are not imposed on the turbocharger structure or exhaust manifold. Never allow the engine exhaust elbow to support any external loads from any of the exhaust system components. At least one flexible joint or bellows must be installed between the engine exhaust elbow and the catalyst. Flexible connections are needed to isolate engine movement and vibration and to offset piping expansion and contraction.

Piping Considerations

Avoid cantilevering loads off the end of the catalytic converter assembly. Be sure to consider the loads imposed to the catalytic converter from vertical exhaust stacks and exit piping. Never place more than 68 kg (150 lb) of unsupported piping or silencing equipment directly on the converter flanges. Anchor piping on one side of the converter only. Allow one side of the aftertreatment system room for thermal expansion. When lifting the catalytic converter, only use the ANSI flanges. The flanges are the only structural components of the converter body.

Exhaust Backpressure

Backpressure effects the response of the engine to load changes, exhaust temperatures, and fuel consumption. Exhaust systems must be designed to provide the best compromise between noise and backpressure.

The total exhaust backpressure of the CG137-12 packaged solution must not exceed the following:

• Total back pressure 6.75 kPa (0.98 psi)

• Maximum differential pressure across the catalyst 2.25 kPa (0.33 psi)

Illustration 10	g03403482
kPa equation

Illustration 11	g03403493
psi equation

Where:

• P = Pressure drop (backpressure) measured in kPa and inches of water

• psi = 0.0361 x in. of water column

• kPa = 0.00981 x mm water column

• L = Total equivalent length of pipe in feet or meters

• Q = Exhaust gas flow in cubic feet per minute or cubic meter per minute at rated conditions

• D = Inside diameter of pipe in inches or millimeter

• S = Density of gas in pounds per cubic feet or kilogram per cubic meter

• Ps = Pressure drop of silencer or rain cap measured in kPa or inches of water

Useful conversion factors:

• psi = 0.0361 x inch of water column

• psi = 0.00142 x millimeter of water column

• psi = 0.491 x inch of mercury column

• kPa = 0.0098 x millimeter of water column

• kPa = 0.25 x inch of water

• kPa = 3.386 x inch of mercury column

• kPa = 0.145 psi

Use the following equations to determine values of straight pipe equivalent length for smooth elbows

Illustration 12	g03403544
Standard elbow

Illustration 13	g03403546
Long sweep elbow

Illustration 14	g03403552
45 degree elbow

Illustration 15	g03403597
Square elbow

Where X = 1000 mm or 12 inches

As shown by the equations, if 90 degree elbows are required, long radius elbows with a radius of 1.5 times the pipe diameter helps to lower resistance.

Exhaust backpressure is measured as the engine is operating at rated speed and full load conditions. Use a water manometer or a pressure gauge to measure pressure at the NPT port in the inlet cone of the converter body.

Catalyst Air Fuel Ratio Control Sensors and Wiring

The supplied catalyst and air fuel ratio control are tuned to maintain emissions compliance at or below 0.5g NO_x and 1g NO_x levels. The levels depend upon which catalyst is used. Ensure that the catalyst sensors and electronics are not exposed to extreme temperatures and vibrations. Keep the sensor harnesses and connectors at least 76 mm (3 inch) away from any exhaust component.

Do not expose the supplied catalyst harness to temperatures above 160° C (320° F). The catalyst harness life is typically proportional to the temperature surrounding the harness. The lower exposed temperature the longer the service life of the harness. Secure the harness to the package using wire ties and or ladder clips. Vinyl ladder clips must be located in areas less than 80° C (176° F).

Mounting Restrictions

Illustration 16	g03139536
Recommended vibration analysis points

Structural mounting to the converter body of the catalyst is not permitted. Provide structural support for the catalyst by either the top or the bottom flange of the converter or the exhaust piping. Separately support the catalyst and exhaust piping by the package structure. Do not use the engine exhaust outlet to support the aftertreatment system. Improper mounting can introduce unwanted vibration to the catalyst. Improper mounting can be harmful to the catalyst substrate as well as converter body structure.

Structural mounting to the catalytic converter should be provided by either of the ANSI flanges, or the exhaust piping. Mounting on the flanges will allow thermal expansion of the converter body.

Do not expose the catalyst to vibration levels above 1.67 Grms at any load or operating condition. Measure at the upper and lower most securement point for the catalyst thermocouple harnesses. Use the 221-2370 Analyzer Gp , or equivalent. Obtain measurements 254 mm (10 inch) away from the centerline of the catalyst. Use the recommended vibration analysis points (1) to gather accurate data. Refer to Illustration 2.