Chapter #18 - Review Questions

Current diesel fuel formulated for on-highway use and classified as ULS is required to have what maximum sulfur content?

0.0015%

Which of the following specific gravity values would correspond to that of a typical 2D diesel fuel?

0.840

What is the minimum CN requirement of 1D or 2D on-highway diesel fuel?

40

Technician A states that a catalyst is a substance that enhances or enables a chemical reaction without itself undergoing any change. Technician B states that the laws of thermodynamics dictate that a catalytic reaction must involve a change in the state of the catalyst. Who is correct?

A only

If an additive were required to prevent freeze-up of a fuel crossover pipe, which of the following would be the preferred option?

Add 8 oz. (250 cc) of methyl hydrate to the tanks

Which of the following best describes the term octane rating when applied to a fuel?

Antiknock resistance

Technician A states that all 1D and 2D fuels must be sold with a CN number of exactly 40. Technician B states that refiners and fuel suppliers seasonally adjust the ignition quality of fuels. Who is correct?

B only

Which of the following values is used to measure the heat energy (calorific value) in a fuel?

BTU

The temperature at which a diesel fuel begins to form paraffin wax crystals is known as:

Cloud point

Which of the following components would be more likely to fail if LS fuel were used instead of ULS in a highway diesel engine manufactured after 2007?

Diesel particulate filter (DPF)

The temperature at which a fuel evaporates sufficient flammable vapor to momentarily ignite when a flame is brought close to its surface is known as:

Flash point

As the CN value of a diesel fuel increases, what happens to its ignition temperature?

It decreases

As the octane rating value of a gasoline increases, what can be said of its burn rate?

It decreases

Technician A states that denser fractions of crude petroleums tend to command higher prices than lighter fractions. Technician B states that diesel fuel tends to be more volatile than gasoline. Who is correct?

Neither A nor B

The lowest temperature at which a diesel fuel can be pumped through a fuel system is known as:

Pour point

What substance is commonly added to truck diesel fuel tanks to prevent winter freeze up?

alcohol

Which of the following compounds is a commonly used diesel fuel ignition accelerator?

cyclohexanol nitrate

Which of the following diesel fuel additives is a commonly used cetane improver?

cyclohexanol nitrate