NAUI Dive Master Combined Verified Multiple
Choice and Conceptual Actual Emended Exam
Questions With Reviewed 100% Correct
Detailed Answers
Guaranteed Pass!!Current Update
Q1: What are the two most common types of scuba cylinder valves in use today?
ANSWER
K-valve and DIN valve
Q2: Which valve type threads directly into a regulator without using an O-ring seal
on the face of the valve?
ANSWER
DIN valve
Q3: What is a key benefit of using a DIN valve over a K-valve?
ANSWER
Better threaded connection, reducing the risk of O-ring extrusion under high
pressure.
Q4: What is the typical working pressure range for a DIN valve used in technical
diving?
ANSWER
Up to 344 bar (5,000 psi), depending on the valve rating.
,Q5: What feature distinguishes a balanced valve from an unbalanced valve?
ANSWER
In a balanced valve, operating force is unaffected by internal cylinder pressure.
Q6: Which specialty valve allows two regulators to be attached to one cylinder?
ANSWER
Y-valve
Q7: What is the function of a burst disk in a scuba valve?
ANSWER
To relieve pressure if the cylinder becomes dangerously overpressurized.
Q8: Where is the burst disk typically located on a scuba valve?
ANSWER
Threaded into the valve body, venting to the atmosphere if it ruptures.
Q9: What is the thread type on most U.S. scuba cylinder necks with K-valves?
ANSWER
3/4"–14 NPSM (National Pipe Straight Mechanical)
Q10: What component inside a valve prevents air from escaping when the valve is
closed?
ANSWER
The seat—typically made of resilient material to form a seal.
Q11: What is a reserve valve and is it still commonly used?
ANSWER
,A valve with a mechanical pressure-triggered reserve feature (J-valve).
No, they are now mostly obsolete due to use of SPGs (submersible pressure
gauges).
Q12: What valve marking indicates compatibility with oxygen-enriched mixes?
ANSWER
“OXY CLEAN” or “OXY SERVICE” indicating proper cleaning and materials for high
oxygen use.
What pressure will a scuba cylinder with a rated working pressure of 3000 psig
(207 bar), be exposed to during a hydrostatic test? - ANSWER 5000 psig (345
bar)
Which principle represents one basis for the hydrostatic testing of scuba
cylinders? - ANSWER Permanent expansion
If a visual cylinder inspection reveals corrosion inside a scuba cylinder, it may
require cleaning by a process called: - ANSWER Tumbling
Which of the following is considered proper care of a scuba cylinder? - ANSWER
Preventing moisture from entering the cylinder.
Two cylinder valves in common use today are: - ANSWER The K-valve and DIN
valve.
, Which valve is an example of a special scuba valve that is required for certain
types of specialty diving such as deep diving with a single cylinder? - ANSWER
Y valve
Which internal valve designs are available in the first stage of scuba regulators? -
ANSWER Piston; Diaphragm
Which valve is unaffected by cylinder air pressure with regard to the force needed
to operate the valve? - ANSWER Balanced
Which regulator second stage design uses air pressure rather than mechanical
leverage to open the main valve? - ANSWER Pilot
In the event of a regulator first stage malfunction, which type of valve design
would be likely to eliminate air flow to the diver? - ANSWER Upstream
When considering a regulator for purchase or use, an important point to
remember is that certain regulators may not be capable of delivering ______ flow
rates at ______ cylinder pressure during an air sharing emergency. - ANSWER
high; low
Which diving instrument incorporates a Bourdon tube mechanism? - ANSWER
Cylinder pressure gauges
Choice and Conceptual Actual Emended Exam
Questions With Reviewed 100% Correct
Detailed Answers
Guaranteed Pass!!Current Update
Q1: What are the two most common types of scuba cylinder valves in use today?
ANSWER
K-valve and DIN valve
Q2: Which valve type threads directly into a regulator without using an O-ring seal
on the face of the valve?
ANSWER
DIN valve
Q3: What is a key benefit of using a DIN valve over a K-valve?
ANSWER
Better threaded connection, reducing the risk of O-ring extrusion under high
pressure.
Q4: What is the typical working pressure range for a DIN valve used in technical
diving?
ANSWER
Up to 344 bar (5,000 psi), depending on the valve rating.
,Q5: What feature distinguishes a balanced valve from an unbalanced valve?
ANSWER
In a balanced valve, operating force is unaffected by internal cylinder pressure.
Q6: Which specialty valve allows two regulators to be attached to one cylinder?
ANSWER
Y-valve
Q7: What is the function of a burst disk in a scuba valve?
ANSWER
To relieve pressure if the cylinder becomes dangerously overpressurized.
Q8: Where is the burst disk typically located on a scuba valve?
ANSWER
Threaded into the valve body, venting to the atmosphere if it ruptures.
Q9: What is the thread type on most U.S. scuba cylinder necks with K-valves?
ANSWER
3/4"–14 NPSM (National Pipe Straight Mechanical)
Q10: What component inside a valve prevents air from escaping when the valve is
closed?
ANSWER
The seat—typically made of resilient material to form a seal.
Q11: What is a reserve valve and is it still commonly used?
ANSWER
,A valve with a mechanical pressure-triggered reserve feature (J-valve).
No, they are now mostly obsolete due to use of SPGs (submersible pressure
gauges).
Q12: What valve marking indicates compatibility with oxygen-enriched mixes?
ANSWER
“OXY CLEAN” or “OXY SERVICE” indicating proper cleaning and materials for high
oxygen use.
What pressure will a scuba cylinder with a rated working pressure of 3000 psig
(207 bar), be exposed to during a hydrostatic test? - ANSWER 5000 psig (345
bar)
Which principle represents one basis for the hydrostatic testing of scuba
cylinders? - ANSWER Permanent expansion
If a visual cylinder inspection reveals corrosion inside a scuba cylinder, it may
require cleaning by a process called: - ANSWER Tumbling
Which of the following is considered proper care of a scuba cylinder? - ANSWER
Preventing moisture from entering the cylinder.
Two cylinder valves in common use today are: - ANSWER The K-valve and DIN
valve.
, Which valve is an example of a special scuba valve that is required for certain
types of specialty diving such as deep diving with a single cylinder? - ANSWER
Y valve
Which internal valve designs are available in the first stage of scuba regulators? -
ANSWER Piston; Diaphragm
Which valve is unaffected by cylinder air pressure with regard to the force needed
to operate the valve? - ANSWER Balanced
Which regulator second stage design uses air pressure rather than mechanical
leverage to open the main valve? - ANSWER Pilot
In the event of a regulator first stage malfunction, which type of valve design
would be likely to eliminate air flow to the diver? - ANSWER Upstream
When considering a regulator for purchase or use, an important point to
remember is that certain regulators may not be capable of delivering ______ flow
rates at ______ cylinder pressure during an air sharing emergency. - ANSWER
high; low
Which diving instrument incorporates a Bourdon tube mechanism? - ANSWER
Cylinder pressure gauges
