5287A 2 Mercury SWITCH BOX

Introduction
Do not perform any procedure in this Special Instruction until you read this information and you understand this information.The Caterpillar catalytic converter is designed to convert carbon monoxide, hydrocarbons, and aldehydes into carbon dioxide and water. The equations in Table 1 are the unbalanced chemical reactions.
Table 1
Unbalanced Chemical Reactions
Carbon Monoxide CO + O2 ⇒ CO2
Hydrocarbons CxHy + O2 ⇒ CO2 + H2O
Aldehydes CxHyO + O2 ⇒ CO2 + H2O Substrate - A layer that lies underneath another layerConversion efficiency - The ratio of a systems output that is compared to the systems inputCatalyst - A catalyst is a substance that accelerates a chemical reaction without being affected by the reaction.The conversion is accomplished by a process that is called oxidation. Oxidation of CO does not occur spontaneously at ambient conditions. Therefore, a catalyst is added to the substrate in order to cause the chemical reactions to occur at lower temperatures. The catalyst is designed to have a conversion efficiency for one or more specific pollutants within a specific operating range. The catalyst is designed to have a 93 percent carbon monoxide conversion efficiency in natural gas engines and a 70 percent carbon monoxide conversion efficiency in diesel engines.
Illustration 1 g01046023The efficiency of a catalyst is dependent upon the amount of the catalyst that is used, the properties of the catalyst, and the temperature of the exhaust gas. This catalyst is designed for use in stationary applications with the following characteristics:
Diesel and gas engines
Engines with 372 kW (500 hp) and higher power ratings
A temperature range of 315 °C (600 °F) to 705 °C (1300 °F)Conversion of CO starts around 121 °C (250 °F). As temperature increases, the conversion efficiency of the catalyst increases. Refer to Illustration 1.Description
The catalytic converter has two basic profiles: rectangular and cylindrical.The rectangular profile is used with larger engines. Refer to Illustration 2.
Illustration 2 g01043701
Rectangular profile
The cylindrical profile is used with smaller engines. Refer to Illustration 3. The cylindrical profile is available with one or two-element blocks. Refer to Illustration 4.
Illustration 3 g01043654
Cylindrical profile
Illustration 4 g01067281The rectangular profile and the cylindrical profile are available in various sizes. The variations are dependent upon the volume of catalyst that is needed for the application. Refer to Table 8 for part numbers for the catalysts.The substrate of the catalyst element includes a stainless steel foil that is contained by a stainless steel frame. The foil surface is coated with catalyst material. The materials are usually metals of the platinum group. These metals are selected due to the high levels of activity and durability. As exhaust gas flows through the catalyst, the thin foil walls provide a large surface area that allows the chemical reactions to take place.The cylindrical substrate is 88.90 mm (3.5 inch) thick with a diameter that is determined by the type of engine, the type of fuel, and the horsepower rating.The rectangular substrate is manufactured as a block. Each block measures 590.55 mm (23.25 inch) by 565.15 mm (22.25 inch) by 88.90 mm (3.5 inch).Shipping and Handling
Use care when you handle the catalysts and the converter assemblies. If the catalysts are handled improperly, the thin metal foils may be damaged or nested. This will result in plugged channels. Also, bending or striking of the metal or excessive shock will cause the catalyst to flake off resulting in lower efficiency of conversion.Installation
The converter resembles the size and shape of a muffler. The assembly is normally installed in the same manner as a muffler. The assembly must be isolated from engine vibration and from external loading due to thermal expansion. The assembly is not designed to be a structural member. Avoid excess stresses on the assembly.Installation Procedure for the Converter Assembly
Illustration 5 g01044819
Example of the converter that is installed upstream of the muffler
(A) Converter
(B) Muffler
Install the converter assembly in a location that i