LEC Emissions Control Systems 2

Question 1

Which EPA tier standard applies to newly manufactured locomotive engines after January 1, 2015?

Accepted Answer

Tier 4

Answer

EPA Tier 4 standards, effective January 1, 2015, set the most stringent emissions limits for newly manufactured line-haul and switch locomotives.

Question 2

What does NOx stand for in the context of locomotive emissions?

Accepted Answer

Nitrogen oxides

Answer

NOx is the collective term for nitrogen oxides (primarily NO and NO₂) produced during high-temperature combustion in diesel engines.

Question 3

A locomotive's diesel oxidation catalyst (DOC) primarily reduces which pollutant?

Accepted Answer

Carbon monoxide and hydrocarbons

Answer

The diesel oxidation catalyst oxidizes carbon monoxide (CO) and unburned hydrocarbons (HC) into carbon dioxide and water.

Question 4

Under the EPA's smoke opacity standards, what is the maximum allowable exhaust opacity during a full-load acceleration for a Tier 0 locomotive?

Accepted Answer

40%

Answer

Tier 0 locomotives are allowed a maximum smoke opacity of 40% during full-load acceleration under EPA regulations.

Question 5

What is the primary reason diesel particulate filters (DPFs) require periodic regeneration?

Accepted Answer

To burn off accumulated soot and restore filter flow

Answer

DPF regeneration burns off trapped soot at high temperatures to restore normal exhaust backpressure and filter efficiency.

(LEC) Locomotive Engineer Certification Practice Test