NAUI Equipment Use & Maintenance 3 — Questions and Answers
Question 1: What is the primary purpose of a tank boot (cylinder boot)?
- To protect the cylinder valve from impact
- To provide a stable upright base and protect the cylinder bottom (Correct answer)
- To insulate the cylinder from temperature changes
- To identify the cylinder's hydrostatic test date
Correct answer: To provide a stable upright base and protect the cylinder bottom
A tank boot fits over the curved bottom of a cylinder to allow it to stand upright and to protect the metal from abrasion.
Question 2: During a post-dive equipment check, a diver finds that the BCD over-pressure relief valve (OPV) opens spontaneously at low inflation. What should the diver do?
- Continue diving; OPVs opening at low pressure is normal
- Tape the OPV shut to prevent premature venting
- Remove the BCD from service until the OPV is serviced or replaced (Correct answer)
- Add more weight to compensate for unexpected buoyancy loss
Correct answer: Remove the BCD from service until the OPV is serviced or replaced
An OPV that opens at low pressure indicates the valve spring has weakened or debris is preventing a proper seal, making the BCD unreliable and requiring service.
Question 3: Why must the dust cap be secured on a first-stage regulator before rinsing?
- To prevent corrosion of the high-pressure seat
- To stop water from entering the first stage and contaminating the internals (Correct answer)
- To keep the o-ring from expanding during the rinse
- Both A and B are correct
Correct answer: To stop water from entering the first stage and contaminating the internals
The dust cap keeps water out of the inlet port so it cannot reach internal components, which would promote corrosion and contamination.
Question 4: Which symptom most clearly indicates a regulator second stage needs professional servicing?
- Slight resistance when pressing the purge button
- A faint hiss of continuous free-flow at the surface (Correct answer)
- Occasional bubbles rising from the mouthpiece on exhale
- Mild resistance on inhalation compared to a new regulator
Correct answer: A faint hiss of continuous free-flow at the surface
Continuous free-flow indicates the demand valve is not seating properly, wasting air and potentially overwhelming a diver's ability to manage gas supply.
Question 5: What is the recommended interval for professional regulator servicing according to most manufacturers and NAUI standards?
- Every 6 months regardless of usage
- Annually or after every 100 dives, whichever comes first (Correct answer)
- Every 2 years if stored properly between dives
- Only when a performance problem is noticed
Correct answer: Annually or after every 100 dives, whichever comes first
Most manufacturers and NAUI recommend annual servicing or after 100 dives (whichever comes first) to replace wear parts and ensure reliable performance.
Question 6: A diver's dive computer floods during a dive. What is the safest immediate course of action?
- Continue the dive using estimated bottom time and ascent rate
- Buddy up closely and follow the computer-equipped buddy's profile (Correct answer)
- Ascend immediately to the surface using a slow, controlled rate
- Switch to a backup SPG and use printed decompression tables
Correct answer: Buddy up closely and follow the computer-equipped buddy's profile
Staying close to a buddy with a functioning computer allows the affected diver to follow a safe ascent profile without abandoning the dive.
Question 7: What material are most quality diving mask skirts made from, and why?
- Polycarbonate, for impact resistance
- Silicone, for durability and low-allergen properties (Correct answer)
- Natural rubber, for superior sealing
- Neoprene, for insulation against cold water
Correct answer: Silicone, for durability and low-allergen properties
Silicone is the preferred material for mask skirts because it is durable, UV-resistant, hypoallergenic, and maintains its seal over many years.
NAUI Equipment Use & Maintenance 3
What is the primary purpose of a tank boot (cylinder boot)?