IDC Dive Equipment & Technology 2

Question 1

What is a dive computer's 'no-decompression limit' (NDL) display and why is it critical for divers?

Accepted Answer

The remaining time a diver can stay at current depth without incurring a decompression obligation

Answer

The battery remaining in the computer

Answer

The total dive time elapsed

Answer

The depth limit for recreational diving

Question 2

What is the purpose of the 'dump valve' on a BCD?

Accepted Answer

To rapidly release air from the BCD, used during ascent to prevent uncontrolled rise

Answer

To add air to the BCD quickly during an ascent

Answer

To drain water from the BCD after diving

Answer

To connect the inflator hose to the tank

Question 3

What is enriched air nitrox and what are its key advantages and limitations compared to standard air?

Accepted Answer

A breathing mixture with higher oxygen content than air, offering longer NDLs but with an oxygen toxicity risk and maximum depth limit

Answer

Air mixed with pure oxygen for unlimited bottom time

Answer

A gas mixture that eliminates the risk of decompression sickness entirely

Answer

A specialty gas used only in technical diving

Question 4

What regular maintenance is required for a scuba regulator to ensure safe performance?

Accepted Answer

Annual or manufacturer-specified service by a qualified technician, plus fresh water rinsing after every use

Answer

Rinse with fresh water after use only — no other maintenance required

Answer

Replacement every 5 years regardless of condition

Answer

Daily disassembly and lubrication by the diver

Question 5

What is the purpose of a surface marker buoy (SMB) and when should it be deployed?

Accepted Answer

To signal the diver's position at the surface during ascent or after surfacing, especially in areas with boat traffic

Answer

To mark the dive site location before diving

Answer

To attach the guideline to the dive site structure

Answer

To measure water depth from the surface

Question 6

What is the difference between a 'piston' first stage and a 'diaphragm' first stage regulator?

Accepted Answer

Piston stages use a moving piston to reduce pressure; diaphragm stages use a flexible membrane isolating internal parts from water, making them preferable in cold or contaminated water

Answer

They are identical in function — only the brand name differs

Answer

Piston stages are for warm water only; diaphragm stages are for recreational use

Answer

Diaphragm stages are lower quality than piston stages