D62 MASTER THE DAY

Which instrument used in sewer testing forms bubbles at leaky joints?

• Lead acetate paper
• Boning rod
• Soap solution
• Blower

Answer explanation

Soap solution applied to joints reveals bubbles at leakage points during air test.

Which gas is tested in sewers using a lighted lantern to confirm safe entry?

• Methane
• Carbon dioxide
• Oxygen
• Hydrogen sulfide

Answer explanation

Oxygen presence is confirmed by a lighted lantern burning brightly in the sewer.

Which method is used to set out the centerline of sewer trenches?

• Offset line method
• Diagonal method
• Compass method
• Radiation method

Answer explanation

Offset line method marks the centerline parallel to trench, ensuring accurate layout.

What is the role of boning rods during sewer trenching?

• Detect gas
• Check level
• Lift pipes
• Backfill trenches

Answer explanation

Boning rods are used with sight rails to ensure level and gradient during trenching.

Which test uses a lamp and mirror to check pipe alignment?

• Water test
• Smoke test
• Mirror test
• Ball test

Answer explanation

Mirror test detects straightness using light reflection across pipe length.

During air testing, what pressure drop indicates leakage?

• 5 mm
• 10 mm
• 25 mm
• 40 mm

Answer explanation

A drop greater than 25 mm in air pressure test indicates leakage.

Which of the following gases is identified by flame formation in the upper layer?

• CH₄
• CO₂
• O₂
• H₂S

Answer explanation

Methane is detected by flame formation when a safety lamp is lowered into sewer.

What does lead acetate paper test for?

• CO₂
• CH₄
• H₂S
• O₂

Answer explanation

H₂S presence turns lead acetate paper black in sewer testing.

Which part of the ventilating system allows gases to escape from the sewer?

• Trap
• Ventilating shaft
• Cowl
• Inlet

Answer explanation

Cowl is the top part of the ventilating column that lets gases escape.

Which of the following is a floating hollow object used in sewer cleaning?

• Rake
• Ball
• Pill
• Rod

Answer explanation

Pills are floating hollow balls used to clean medium-sized sewers.