Partial Amendment to Announcement that Prescribes Details
of Safety Regulations for Road Vehicles
 Introduction of a Particulate Matter Inspection Using an Opacimeter 
1. Background
With the tightening of exhaust emission regulations and the advancement of exhaust emission
control technology over the past years, current diesel fueled vehicles are virtually smoke free
throughout their service life and emit little amount of particulate matter ("PM"). Therefore, it has
been decided to introduce into the vehicle inspections a new PM inspection using an opacimeter
capable of measuring SOF (soluble organic fractions) as well as smoke accurately. This new PM
inspection will replace the smoke inspection using smoke meters. Accordingly, examinations using
an opacimeter will also be introduced into the PM testing in the type approval of vehicles.
2. Summary of the Amendment
(1) Scope
1) Type approved vehicles
The Amendment applies to standard and small diesel-fueled vehicles (excluding two-wheeled
vehicles) that are to be type approved not before September 1, 2007 (not before August 1, 2008
for imported vehicles).
2) Non-type approved vehicles
For non-type approved vehicles, the Amendment applies to standard and small diesel fueled
vehicles (excluding two-wheeled vehicles) that are to undergo initial inspection not before
September 1, 2007 (not before August 1, 2008 in the case of imported vehicles).
(2) Limit Value
Light absorption coefficient: 0.80 [m-1]
* This limit value should be applied to the type approval examination, initial inspection,
existing vehicle inspection and other exhaust emission tests of diesel-fueled vehicles.
(3) Qualified Opacimeters
Opacimeters that may be used in inspections and type approval examination should be in
conformity with ISO 11614.
(4) Measurement Method of Light Absorption Coefficient
(i) Condition of opacimeters for measurement
[1] Calibrate the opacimeter at least once a day.
[2] Warm up the opacimeter before use.
[3] Thoroughly remove smoke sediment in the probe and other substances that affect the light
absorption coefficient of exhaust emissions, before measurement.
1
[4] Conduct dew point adjustment and sensitivity adjustment, before measurement.
(ii) Condition of the vehicle
[1] Keep the vehicle stationary and fully warm it up.
[2] Maintain the transmission in neutral and the engine at no load.
[3] Thoroughly remove smoke sediment and other substances in the exhaust pipe that affect the
light absorption coefficient of exhaust emissions.
(iii)Insertion of the probe
Insert the probe into the vehicle's exhaust pipe as deep as its far end.
(iv) Drive the vehicle for measurement
For measurement, drive the vehicle in accordance with the following procedures:
[1] Drive the engine at no load for 5 to 6 seconds.
[2] Rapidly press down on and keep the accelerator pedal pressed for 2 seconds; then, release
the accelerator pedal.
(v) Inflow of exhaust emission to opacimeter
Let exhaust emissions flow continuously into the opacimeter by the exhaust pressure of exhaust
emissions for 5 seconds from the start of accelerator pedal pressing.
(vi) Measurement of the light absorption coefficient
Measure the maximum light absorption coefficient of the exhaust emissions collected during the
collection period mentioned in the above (v).
(vii)Decision of the light absorption coefficient of exhaust emissions
[1] If the measurement result obtained in (vi) is equal to or less than the threshold value in the
table below, adopt the measured value as the light absorption coefficient of exhaust
emissions for the inspected vehicle. If the result exceeds the threshold value, repeat the
measurement after an intermission of at least 4 seconds but not exceeding 10 seconds.
[2] If the result of the repeated measurement following the above [1] is equal to or less than the
threshold value, adopt the remeasured value as the light absorption coefficient of exhaust
emissions for the vehicle. If the result exceeds the threshold value, repeat again the
measurement after an intermission of at least 4 seconds but not exceeding 10 seconds.
[3] If the measurement is repeated a total of three times following the above [2], adopt the
average value of the three measurements from (vi), (vii) [1] and (vii) [2] as the light
absorption coefficient of exhaust emissions for the vehicle.
Limit value
Threshold value
0.80m-1
0.64m-1
2
1.01m-1
0.80m-1
1.27m-1
1.01m-1
1.62m-1
1.29m-1
2.76m-1
2.20m-1
Engine speed
2 sec
2 sec
2 sec
Max. engine speed
Idling engine speed
Warm-up
before measurement
5 sec
Idle, 5-6 sec
5 sec
4-10 sec
Measurement [2]
Conducted when the
measured value in [1]
exceeds the threshold.
Measurement [1]
3
5 sec
4-10 sec
Measurement [3]
Conducted when the
measured value in [2]
exceeds the threshold.