Question 38 OSE01 - Chief Engineer - OSV

The Correct Answer is A. ### Explanation of Correct Option (A) Option A, "Dull or dazzling white flame," is correct because the combination of a dense white smoke exiting the stack (eliminating water vapor) and the resulting white flame indicates **severe air starvation** (poor combustion) and the **release of unburned fuel oil vapor or finely atomized oil mist**. 1. **Dense White Smoke (Excluding Water Vapor):** This type of smoke, often called "cold smoke," is primarily caused by fuel oil droplets or vapor passing through the combustion chamber and uptakes without being completely burned. This is typically an indicator of poor atomization or, more critically, a low-temperature flame or lack of sufficient air (air starvation). 2. **Correlating Flame Color (Dull or Dazzling White):** When air supply is severely restricted (air starvation), the combustion is incomplete and inefficient. This leads to very low flame temperatures in the primary zone. A very cold, white flame (often described as smoking, hazy, or a dazzling/hazy white) results from the presence of large quantities of unburned carbon particles and fuel vapor that are incandescent but not hot enough to achieve the typical bright yellow/orange color of good combustion. In severe cases of cold, incomplete combustion, the flame will appear pale, hazy, and sometimes dazzling white (or dull white), directly correlating with the release of unburned fuel that manifests as dense white stack smoke. ### Explanation of Incorrect Options **B) Yellow flame:** A stable, medium yellow flame is characteristic of **near-perfect or efficient combustion** with an adequate supply of air (slightly above stoichiometric requirements). This type of flame results in minimal, light gray, or invisible stack gases, not dense white smoke. **C) Yellowish orange or golden yellow flame:** A bright, golden yellow or yellowish-orange flame indicates **good combustion** where the air-to-fuel ratio is optimal, maximizing heat transfer. This scenario is associated with clean stack emissions (invisible or very light haze), not dense white smoke, unless the smoke is caused by extremely high soot formation from excessive combustion air (which would produce black smoke, not white). **D) Reddish flame:** A reddish or smoky red flame typically indicates **moderate air starvation** (less severe than the white flame case) or the presence of significant amounts of solid contaminants (like carbon deposits or heavy metals) in the flame, leading to high soot production and generally **black or dark gray smoke**, not dense white smoke (which is characteristic of unburned fuel).