Equipment Knowledge & Maintenance Flashcards

What is the consequence of diving with a wetsuit that has open-cell foam backing exposed at a torn seam?

Answer: Increased water flushing reduces thermal insulation significantly at that area

Exposed open-cell foam at a tear allows water to flush through rather than warm against the skin, sharply reducing insulation in that area.

How does a piston-style first stage differ from a diaphragm-style first stage in terms of seawater exposure?

Answer: In a piston first stage, ambient seawater enters the spring chamber; a diaphragm design isolates internal parts from the water

Open-piston first stages expose the spring and piston to ambient water, while diaphragm designs use a flexible membrane to keep those parts isolated.

A diver's mask fogs repeatedly despite using defog solution. What is the most likely root cause?

Answer: A thin silicone film from manufacturing remains on the lens and must be removed by scrubbing with toothpaste or a commercial mask prep solution

New masks have a silicone release coating on the lens from the mold; scrubbing with non-gel toothpaste removes it and allows defog to work properly.

What should a diver do if they discover a small amount of water in the bottom of their scuba cylinder during a visual inspection?

Answer: Have the cylinder tumbled, dried, and visually re-inspected before refilling

Water inside a cylinder promotes internal corrosion; the cylinder must be tumbled with an abrasive, completely dried, and re-inspected before being put back in service.

Why is it important to crack open a scuba cylinder valve briefly before attaching a regulator?

Answer: To blow out any dust or debris in the valve outlet that could damage first stage O-rings or seats

Briefly opening the valve blows out particles from the valve outlet that could score the O-ring or seat on the first stage during connection.

What does the term 'intermediate pressure' refer to in a two-stage scuba regulator system?

Answer: The reduced pressure delivered by the first stage to the second stage, typically 8–12 bar above ambient

The first stage reduces high cylinder pressure to an intermediate pressure of roughly 8–12 bar over ambient, which the second stage then reduces further to ambient for breathing.

Which seal type is most commonly used at the connection point between a regulator first stage and a scuba cylinder valve?

Answer: A high-pressure O-ring seated in the yoke or DIN fitting

The DIN and yoke (A-clamp) connections both rely on a high-pressure O-ring to create a gas-tight seal between the first stage and the cylinder valve.