quote:

---

The catalytic converter is an emission control device installed in the exhaust system. It is installed only on Corolla's sold in the U.S.A.

The catalytic converter looks somewhat like a muffler, but it performs an important job in maintaining cleaner air.If a large amount of unburned gasoline flows into the converter, it may overheat and create a fire hazard. To prevent this, observe the following precautions:

Do not drive with an extremely low fuel level. This may cause engine misfire which creates an extra load for the converter.

Do not allow the engine to run at fast idle speed for more than ten minutes or at normal idle speed for more than twenty minutes.

Do not park the car over dry grass or over anything that might burn easily.

Do not turn off the ignition while the car is moving.

Toyota Owner's Manual, Section 1, page 1.

---

said by retired17 :

Our local news station KNX reported that a malfunctioning catalytic converter can spit out hot metal shavings. It's what probably caused all the fires.

Catalytic Converter

Muffler baffles

quote:

---

Once your catalytic converter reaches its operating temperature (known as "light off temperature" and usually between 400 and 600 degrees Fahrenheit) the catalyst compound coating the inner ceramics start to convert the three regulated harmful emissions into less harmful emissions. The three harmful emissions regulated by the EPA are Carbon monoxide (CO), Hydrocarbons (or VOCs for Volatile Organic Compounds), and Nitrogen compounds (NOx).

---

Ceramic matrix inside converter

said by retired17 :

Today in S. California, there were numerous spot fires caused by a failed catalytic converter. Do these converters spill their guts when they fail? Or do they actually have to first strike an object on the roadway then spill their guts?

quote:

---

DIAMOND BAR, Calif. (AP) - Los Angeles County fire officials say a malfunctioning catalytic converter on a vehicle is believed to have caused brush fires that threatened homes in the city of Diamond Bar.

Inspector Frederic Stowers says a malfunctioning catalytic converter can spit out hot metal shavings which would account for the multiple ignition points of the blaze late Tuesday morning.

Stowers says the 50-acre blaze is 60 percent contained but there's very little fire activity and firefighters are in the mop-up process.

---

quote:

---

How Catalytic Converters Get Hot

Catalysts reduce emissions by accelerating the combustion of pollutants leaving the engine. In doing this job, they get hot. The outside metal temperatures of some types of converters may approach 800 to 1000 F under conditions of extremely high engine loading. However, measurements by the United States Forest Service have shown surface temperatures equally as high in the exhaust systems of pre-1975 cars at extreme engine load conditions. Therefore, with this discovery, catalytic converter surface temperatures do not represent a new type of problem for automobile manufacturers and users as long as the engine is running properly.

However, if there is a partial ignition system failure, such as one or more misfiring spark plug or defective ignition wires, the temperatures of the catalytic converter surfaces and the exhaust system downstream from the converter may reach 1200 to 1400 F. This is because of the abnormal amount of unburned fuel delivered by the nonfiring cylinders. Further, once hot, the converter will take longer to cool off than other parts of the exhaust system because of its greater mass. This points out the need for careful attention to vehicle maintenance and alertness by vehicle owners to any signs of abnormal engine operation.

...

It should be noted that vegetation fires caused by hot automobile exhaust systems occurred before the advent of catalyst-equipped cars, and will occur in the future. The Forest Service has periodically conducted tests of cars for fire hazards since 1967 because of the long-standing concern by that agency over vehicle-induced fires in national forest recreational areas.

...

Never park a catalyst-equipped car, or any car, on a pile of dry leaves or other dry vegetation. Normal caution in how you use your car is all that is needed to avoid catalyst fires.

---

Monolithic design is a ceramic honeycomb style converter. This is the most popular design in use.

quote:

---

Q What is A Substrate?

A It is the material inside the shell of the converter. There are two types of original equipment substrates: Pelletized, which consists of thousands of BB-sized ceramic pellets and Monolithic, which is a ceramic "honeycomb" style. The replacement converters listed in this catalog have monolithic substrates.

Q What is A Catalyst?

A It is a thin coating of precious metals (rhodium, platinum and paladium) applied to the surface of the substrate material. Its function is to assist in the chemical reactions that are required to lower the emission levels.

Q What Makes A Converter Become Red Hot?

A A Converter will get red hot when raw fuel is introduced directly into it. This is not the problem of the converter itself, but the result of a problem with the fuel system or ignition that allows unburned fuel to pass through the engine to the converter. Possible causes are improper ignition timing, fouled spark plugs, and air pump failure.

Q What Causes A Converter To Become Clogged?

A If a converter is operated too long at a high temperature, its substrate may "melt down" and turn into a solid mass inside the converter. The vehicle may seem sluggish, as if there were a loss of power. Again, an engine and/or fuel system malfunction is allowing a rich fuel mixture to reach the converter. If the problem is not diagnosed and corrected, future converter failures may occur.

---

quote:

---

2.The catalyst itself is most often a precious metal. Platinum is the most active catalyst and is widely used. It is not suitable for all applications, however, because of unwanted additional reactions and/or cost. Palladium and rhodium are two other precious metals used. Platinum and rhodium are used as a reduction catalyst, while platinum and palladium are used as an oxidization catalyst. Cerium, iron, manganese and nickel are also used, although each has its own limitations. Nickel is not legal for use in the European Union (due to reaction with carbon monoxide). While copper can be used, its use is illegal in North America due to the formation of dioxin.

---