BOC Boiler Systems and Steam 2

Question 1

What is the recommended procedure when a boiler safety relief valve lifts (opens)?

Accepted Answer

Identify and correct the cause of overpressure before resuming operation

Answer

A lifting safety valve signals a potentially dangerous overpressure condition; the root cause must be found and corrected before safely resuming boiler operation.

Question 2

In a steam heating system, what is 'two-pipe' piping?

Accepted Answer

A system with supply and return piping kept separate

Answer

A two-pipe steam system uses separate supply and return mains, allowing more precise control and quicker condensate return compared to single-pipe systems.

Question 3

What is 'scale' in a boiler, and what problem does it cause?

Accepted Answer

Mineral deposits on heat transfer surfaces; it reduces heat transfer efficiency

Answer

Scale is mineral buildup (primarily calcium and magnesium compounds) on waterside surfaces that acts as insulation, reducing heat transfer and potentially causing overheating.

Question 4

What condition is described as 'priming' in a steam boiler?

Accepted Answer

Violent water surging that carries water droplets into the steam supply

Answer

Priming occurs when the boiler water surges violently, entraining water droplets in the steam, which can cause water hammer and damage downstream equipment.

Question 5

What is the purpose of a feedwater economizer in a boiler system?

Accepted Answer

To preheat feedwater using waste heat from flue gases

Answer

An economizer recovers heat from exhaust flue gases to preheat incoming feedwater, improving overall boiler efficiency and reducing fuel consumption.

BOC - Building Operator Certification Practice Test

BOC - Building Operator Certification Practice Test

BOC Boiler Systems and Steam 2