How do I measure catalyst size?

<A Complete Guide to Measuring the Core of an Automobile Catalytic Converter: A Professional Guide from Tool Selection to Size Estimation>

A must-read for merchants, repairmen, and recycling practitioners: Accurate measurement to avoid cost losses

The core value of an automotive catalytic converter depends on the size, material, and honeycomb structure of the inner core. Whether it is replacing accessories, recovering precious metals, or evaluating performance, accurate measurement of the inner core parameters is essential. However, many users mismeasure the outer shell size or ignore the internal structure details, resulting in compatibility issues or underestimation of value. This article will systematically explain the professional equipment measurement method, simple tool alternatives, and the skills of calculating the inner core size through the outer shell, covering the entire process from basic operation to advanced judgment.

一. Core preparation before measurement

1. Safety and tools

Safety protection: Wear anti-cut gloves and goggles (the ceramic core is fragile and may produce sharp debris.

Tool selection:

-Professional equipment: digital caliper (accuracy ±0.01mm), endoscope (observe internal blockage or damage), infrared thermometer (assist in judging thermal performance)

-Alternatives: tape measure, strong flashlight, coin (compare hole density)

2.Distinguish the inner core from the outer shell

The inner core is mostly made of ceramic or metal honeycomb carrier, and the outer shell is stainless steel or aluminum-plated steel. When measuring, it is necessary to peel off the outer metal shell or observe through the cut (if it has been disassembled)

二. Accurate measurement process under professional equipment

1. Inner core shape and size measurement
-Shape judgment (illustration assistance):
Circular core: directly measure the diameter (the widest part perpendicular to the center line)
Oval/track core: record the major and minor axes (such as 4.5 inches × 2.8 inches)
Square core: measure the length and width (most common in heavy vehicles)
-Length measurement: from one end of the inner core to the other, ignoring the outer shell welding part (the error must be controlled within ±1mm)

2. Cellular density (CPI) detection
-Professional method: Use a magnifying glass or microscope to count the number of holes in a 1-inch × 1-inch area (such as 400CPI, 600CPI). High CPI (≥600) usually corresponds to higher platinum group metal content
-Simple method: Cover the area with a coin (about 19mm in diameter) and estimate the ratio of the number of holes

3. Material and structure evaluation
-Ceramic core: Check for cracks (tap and listen for abnormal sounds)
-Metal core: Confirm whether it is Fe-Cr-Al stainless steel (such as SUS441), which is resistant to high temperatures and has a high recycling premium

三. Emergency plan when there is no professional equipment

1. Use the outer shell size to calculate the inner core
-Diameter relationship: The metal core is usually consistent with the outer shell diameter (tolerance ±2mm); the ceramic core is wrapped in an insulation layer, and the inner core diameter is 5-10mm smaller than the outer shell
-Length estimation: The inner core length is 10-20mm shorter than the outer shell (need to be verified in conjunction with the vehicle model database)
2. Quick determination of hole density
Flashlight transmission method: Strong light irradiates the inner core cross section, low CPI (≤300) has high transmittance, and high CPI (≥600) presents dense mesh shadows
3. Damage and blockage diagnosis
-Back pressure test: Remove the oxygen sensor and install a simple pressure gauge. When the pressure is >20.7kPa at idle, it indicates that the inner core is blocked
-Temperature difference method: Measure the temperature difference between the inlet and outlet of the converter after driving, which should be ≥38℃ normally (if the temperature difference is too small, the prompt will fail)

四. Core parameters that affect the value of the inner core

1. Size and shape: round cores are highly versatile, while oval/special-shaped cores need to be customized.

2. Material marking: Some brands have PGM codes engraved inside (such as Pt:Pd:Rh=5:3:2), which directly determines the recycling value.

3. Common errors:

- Mistakenly taking the outer shell length as the inner core length (need to deduct 10-20mm).

- Undetected channel blockage rate (blockage rate > 0.2% requires downgrade)

五.Refer to the table for regular dimensions

Ceramic catalytic converter carrier specifications	Machining mid-section specifications
93*100	101*110
100*100	110*110
103*100	110*110
106*100	114*110
110*100	120*110
118*100	127*110
123*100	130*110
132*100	140*110
144*100	152*110

 

Ready to Upgrade?
👉 Click to Order Now | 📞 Contact Sales: