Page 1 of 68
ADCI Surface Supplied Mixed Gas Diver Certification
EXAM ACTUAL EXAM COMPLETE QUESTIONS AND
CORRECT ANSWERS LATEST UPDATE THIS YEAR
EXAM Coverage
• HeO2 Limits: Maximum depth of 300 fsw for surface-supplied mixed gas.
• Oxygen Limits: Normal working
• Thermal: Hot water suits are mandatory for all helium-oxygen diving.
• Communication: Unscramblers are required for all helium diving due to voice distortion.
• Gas Purity: Helium must be Grade A or B; Oxygen must be USP Grade.
1. What is the maximum depth for ADCI Surface Supplied Mixed Gas diving?
A. 190 fsw
B. 250 fsw
C. 300 fsw
D. 380 fsw
,Page 2 of 68
Rationale: 300 fsw is the standard limit; beyond this, saturation diving is generally
required.
2. Which gas law explains why a diver's
increases as they descend?
A. Charles's Law
B. Boyle's Law
C. Dalton's Law
D. Henry's Law
Rationale: Dalton’s Law states partial pressure is proportional to the total pressure.
3. Helium is used in deep diving primarily because it is:
A. Cheaper than air
B. Non-narcotic
C. Easier to decompress than nitrogen
D. Highly insulating
Rationale: Unlike nitrogen, helium does not cause narcosis at depth.
4. What is the minimum number of personnel for a mixed gas diving operation?
A. 3
B. 4
C. 5
,Page 3 of 68
D. 6
Rationale: ADCI requires a Supervisor, Diver, Standby Diver, and two Tenders (one for
the diver, one for standby).
5. What is the primary symptom of CNS Oxygen Toxicity?
A. Joint pain
B. Convulsions
C. Skin rash
D. Itching
Rationale: Visualized by the mnemonic CONVENTID; convulsions are the most
dangerous acute symptom.
6. The "120 Rule" in diving refers to:
A. Maximum depth for air
B. Maximum bottom time for gas
C. The depth/time sum for maximum exertion
D. A rule of thumb for gas blending
Rationale: It is a legacy rule used to gauge risk, though modern tables replace it.
7. HPNS stands for:
A. High Pressure Nitrogen System
B. High Pressure Nervous Syndrome
C. Hyperbaric Pulmonary Nasal Syndrome
, Page 4 of 68
D. Helium Pressure Narcotic System
Rationale: It is a neurological disorder caused by rapid compression at great depths.
8. Which gas has the highest thermal conductivity?
A. Oxygen
B. Nitrogen
C. Helium
D. Argon
Rationale: Helium pulls heat away from the body 6x faster than air, necessitating hot
water suits.
9. What is the standard
limit for a diver at a working depth?
A. 1.0 ata
B. 1.3 ata
C. 1.6 ata
D. 2.0 ata
Rationale: 1.3 to 1.4 ata is the recommended working limit to provide a safety buffer.
10. A gas reclaim system is used to:
A. Clean the air in the chamber
B. Recover and recycle exhaled helium
ADCI Surface Supplied Mixed Gas Diver Certification
EXAM ACTUAL EXAM COMPLETE QUESTIONS AND
CORRECT ANSWERS LATEST UPDATE THIS YEAR
EXAM Coverage
• HeO2 Limits: Maximum depth of 300 fsw for surface-supplied mixed gas.
• Oxygen Limits: Normal working
• Thermal: Hot water suits are mandatory for all helium-oxygen diving.
• Communication: Unscramblers are required for all helium diving due to voice distortion.
• Gas Purity: Helium must be Grade A or B; Oxygen must be USP Grade.
1. What is the maximum depth for ADCI Surface Supplied Mixed Gas diving?
A. 190 fsw
B. 250 fsw
C. 300 fsw
D. 380 fsw
,Page 2 of 68
Rationale: 300 fsw is the standard limit; beyond this, saturation diving is generally
required.
2. Which gas law explains why a diver's
increases as they descend?
A. Charles's Law
B. Boyle's Law
C. Dalton's Law
D. Henry's Law
Rationale: Dalton’s Law states partial pressure is proportional to the total pressure.
3. Helium is used in deep diving primarily because it is:
A. Cheaper than air
B. Non-narcotic
C. Easier to decompress than nitrogen
D. Highly insulating
Rationale: Unlike nitrogen, helium does not cause narcosis at depth.
4. What is the minimum number of personnel for a mixed gas diving operation?
A. 3
B. 4
C. 5
,Page 3 of 68
D. 6
Rationale: ADCI requires a Supervisor, Diver, Standby Diver, and two Tenders (one for
the diver, one for standby).
5. What is the primary symptom of CNS Oxygen Toxicity?
A. Joint pain
B. Convulsions
C. Skin rash
D. Itching
Rationale: Visualized by the mnemonic CONVENTID; convulsions are the most
dangerous acute symptom.
6. The "120 Rule" in diving refers to:
A. Maximum depth for air
B. Maximum bottom time for gas
C. The depth/time sum for maximum exertion
D. A rule of thumb for gas blending
Rationale: It is a legacy rule used to gauge risk, though modern tables replace it.
7. HPNS stands for:
A. High Pressure Nitrogen System
B. High Pressure Nervous Syndrome
C. Hyperbaric Pulmonary Nasal Syndrome
, Page 4 of 68
D. Helium Pressure Narcotic System
Rationale: It is a neurological disorder caused by rapid compression at great depths.
8. Which gas has the highest thermal conductivity?
A. Oxygen
B. Nitrogen
C. Helium
D. Argon
Rationale: Helium pulls heat away from the body 6x faster than air, necessitating hot
water suits.
9. What is the standard
limit for a diver at a working depth?
A. 1.0 ata
B. 1.3 ata
C. 1.6 ata
D. 2.0 ata
Rationale: 1.3 to 1.4 ata is the recommended working limit to provide a safety buffer.
10. A gas reclaim system is used to:
A. Clean the air in the chamber
B. Recover and recycle exhaled helium
