Filters for Motor Vehicle Smoke Meter

Introduction and Use of Filters for Motor Vehicle Smoke Meter – The opacimeter is an instrument used to measure the smoke content in the exhaust gas emitted by sedans, also known as the transmission opacimeter for smoke verification/calibration. The core component of the automotive transmittance meter is a standard neutral filter used in motor vehicles. Mainly used for the measurement of exhaust gas emitted by diesel engines. Use a piston pump to extract a certain volume of exhaust gas from the diesel engine exhaust pipe at regular times and pass it through a certain area of filter paper. The smoke and dust particles in the exhaust are trapped on the filter paper and the filter paper is stained black. Measure the absorbance of the filter paper using photoelectric measuring equipment, which represents the size of smoke in the exhaust. The smokemeter mainly consists of a piston pump, sampling equipment, and photoelectric filter measuring equipment. The measurement is generally repeated three times to obtain the arithmetic mean value as the measured smoke value. The numerical scale of smoke value is 0-10, with zero smoke for blank filter paper and 10 smoke for all black filter paper.



The main pollutants emitted by diesel vehicles are particles, which are 30-60 times more than gasoline engines. They are mainly composed of carbon containing substances (carbon smoke), lead oxides, and high molecular weight organic compounds (oxidation and cracking products of lubricating oil). Carbon smoke is a product of incomplete combustion in diesel engines, mainly composed of diameters ranging from 0.1 to 1.0 μ M is composed of porous carbon particles. When a car starts, accelerates, or goes uphill, the carbon smoke emissions increase due to the rich mixture; Perhaps when the quality of diesel fuel injection is not high and the atomization is poor, it will also increase the emissions of carbon smoke. The harmful substances in carbon smoke cause cancer, reduce air visibility, adhere to the same surface, affect beauty, and corrode metals. Lead oxide can harm the heart, lungs, and hematopoietic system, reducing intelligence

The harmful components contained in diesel vehicle exhaust not only seriously pollute the atmosphere and worsen the environment, but also directly threaten people’s physical health. Therefore, detecting diesel vehicle emissions to reduce pollution is of great significance.

There are two types of smoke meters according to the principle of instrument measurement, one is the filter paper type, and the other is the transmission type. According to national standard regulations, diesel vehicles produced before October 1, 2001 must be tested with a filter paper smoke meter, and diesel vehicles produced after October 1, 2001 must be tested with an opacity photometer.

Through the above introduction, we should have gained an understanding of smoke meters. If we want to learn more about car testing instruments, please follow our website for updates

Extended Reading

Standard neutral filter for motor vehicles (verification/calibration of transmission opacimeters, transmittance meters for automobiles)

The smoke meter filter is a metrological standard device that complies with the verification regulations of JJG976-2010 “Transmission Smoke Meter” and the calibration specifications of JJF “Automotive Transmittance Meter” for indication error verification/calibration.

Overall dimensions: 73 × twenty-seven × 4(mm)

Smoke meter filter transmittance nominal values: 34%, 50%, 58%, 71%, 84%

Setting wavelength of smoke meter filter: 400.0nm~760.0nm

Weighted average of measured transmittance, uncertainty of transmittance: 0.5%

Characteristics of the standard neutral opacimeter filter for motor vehicles produced by Nahong Optoelectronics:

Accurate and Reasonable Setting of Smoke Meter Filter

The smoke meter filter has high long-term stability;

The smoke meter filter can be wiped and cleaned;

The substrate of the filter is made of neutral glass, and compared to neutral density filters using surface coating technology, it has strong friction resistance and high temperature resistance, thus having good long-term stability. After occasional contamination, cleaning with alcohol or optical lens cleaning agent can restore its accurate quantity value


Hanzhong Brisun Optics Co., Ltd. Is the high precision optical element manufacturer provides customized production of Various optical lenses, including spherical lens, cylindrical lens, optical window, mirror, prism, filter, metal base mirror and other high-precision optical elements. The base materials include various optical glass, fused quartz, calcium fluoride (CaF2), zinc selenide (ZnSe), germanium (GE), silicon (SI), sapphire, metal and other materials. And provide antireflective film, high reflection film, spectroscopic film, metal film and other optical coatings.

Welcome to OEM and Purchasing!

Recent Posts
Send Requests
Contact Form Demo (#3)