Diesel Smoke Emission Testing Rules

Maximum allowable black soot content is:
- 2.5 m-1 light absorption coefficient,
- or 48% opacity on the Iyasaka Bosch opacity meter,
- or 66% on the Hartridge Smoke Emission Unit (HSU),
- or an equivalent reading on other recognized smoke emission testers.

Testing conducted on stationary vehicles at normal engine operating temperature.
Engine combustion chamber must not be cooled or fouled; exhaust system must be intact without leaks.
Follow opacity meter manufacturer’s instructions for installation, use, and calibration.
Vehicle placed in neutral gear with the hand brake engaged.
Engine warmed to normal operating temperature before testing.
Sampling probe inserted into the tailpipe connected to a properly configured and calibrated testing device.
Engine accelerated quickly but carefully to maximum speed held for about three seconds to ensure maximum fuel delivery.
Test repeated two more times to achieve three consecutive stable maximum opacity readings within defined tolerances.
The final test result is the arithmetic mean of the three stable readings.
For vehicles with multiple exhaust pipes, test all and record the highest smoke opacity.
After testing, the full-load screw of the injection pump/delivery system is sealed.

Use computer-generated forms for recording test results.
In case of power outage or computer unavailability, manually generate forms in the prescribed format for later encoding.

All vehicle and test data are encoded into data diskettes for upload to regional and central databases.
Printed test result copies must be attached to the Motor Vehicle Inspection Report (MVIR) and given to the vehicle owner.

Tests may be conducted up to one month before vehicle registration.
Test results are valid for 30 days from the test date for registration purposes.

Fifty pesos (P50.00) for motor vehicles under classifications L, M, H, UV, and TX.
Seventy-five pesos (P75.00) for motor vehicles under T or TB classifications.
Additional fifty pesos (P50.00) fee for tests conducted at the vehicle owner’s garage.

All prior circulars, orders, memoranda, and instructions conflicting with this memorandum circular are superseded and amended accordingly.

The memorandum circular takes effect immediately upon issuance on March 1, 1994.