13. The opacity of emissions from diesel-powered heavy vehicles is measured(1) by the roadside, using one of the following opacimeters:— Red Mountain Engineering’s Smoke Check 1667;
— Thermal-Lube’s EXL Diesel Emission Detector; or
— Thermal-Lube’s EXL Combo Opacimeter 5-Gas Analyzer;
(2) in an accredited establishment, using an opacimeter, in accordance with the Society of Automotive Engineers recommended practice J1667 Snap-Acceleration Smoke Test Procedure for Heavy-Duty Diesel Powered Vehicles.