Page 1 of 128
ADCI Surface Supplied Mixed Gas Diver Certification
Exam QUESTIONS AND CORRECT DETAILED SOLUTIONS
WITH RATIONALES LATEST THIS YEAR (2026-2027)
A comprehensive 250-question practice exam for the ADCI Surface Supplied Mixed Gas Diver
Certification.
The questions are fully randomized and cover ADCI Standards, Mixed Gas Physiology (HPNS, O₂
Toxicity, DCS), Diving Physics, Decompression Theory, Equipment (Umbilicals, Helmets,
Chambers), Emergency Procedures, and Gas Mixtures.
1. A tender is preparing a diver for a mixed gas dive. According to ADCI standards regarding the
standby diver, which of the following is required for working dives below 100 FSW?
A) The standby diver must be suited up and breathing on the umbilical, ready for immediate
entry.
B) The standby diver must remain in the chamber.
C) A second dive team must be on-site.
D) The standby diver only needs to be wearing a wetsuit.
Correct Answer: A
Rationale: For depths below 100 FSW, ADCI requires the standby diver to be fully dressed and
breathing on the umbilical to allow for immediate deployment in an emergency .
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2. A diver is using a Heliox mixture at 150 meters. He begins to exhibit tremors and severe
dizziness. What condition is most likely causing this?
A) Nitrogen Narcosis
B) High-Pressure Nervous Syndrome (HPNS)
C) Carbon Dioxide Toxicity
D) Oxygen Toxicity
Correct Answer: B
Rationale: HPNS is induced by high pressure, specifically in deep helium dives, causing tremors
and CNS disturbances .
3. The ADCI International Consensus Standards are recognized as best practices by which federal
agencies?
A) EPA and CDC only
B) OSHA, the U.S. Coast Guard, and the U.S. Army Corps of Engineers
C) NOAA and FEMA
D) The Department of Energy
Correct Answer: B
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Rationale: ADCI standards are specifically cited by OSHA, the USCG, and the Army Corps of
Engineers for commercial diving compliance .
4. If a diver consumes gas at a rate of 2 cubic feet per minute (RMV) at the surface, what will the
consumption rate be at 99 FSW (4 ATA)?
A) 2 cfm
B) 4 cfm
C) 6 cfm
D) 8 cfm
Correct Answer: D
Rationale: Pressure increases from 1 ATA to 4 ATA (99ft). Surface consumption rate (2 cfm)
multiplied by 4 ATA equals 8 cfm.
5. A diver using a surface-supplied mixed gas system experiences a total loss of gas from the
panel. What is the primary piece of equipment that allows him to safely reach the surface?
A) The helmet demand regulator
B) The pneumofathometer hose
C) The bailout cylinder (EGS)
D) The hot water suit manifold
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Correct Answer: C
Rationale: The Emergency Gas Supply (bailout bottle) provides an independent, redundant
breathing gas source to allow the diver to safely return to the surface or bell .
6. To qualify for the initial ADCI Mixed-Gas Diver certification card, what are the minimum dive
requirements?
A) 100 total working dives, any mix
B) 100 Air dives and 50 Mixed-Gas dives
C) 50 Air working dives and 10 Mixed-Gas HeO2 working dives
D) 25 Saturation dives
Correct Answer: C
*Rationale: ADCI requires documented proof of 50 Air working dives and 10 Mixed-Gas HeO2
working dives prior to certification .*
7. The partial pressure of Oxygen (PPO2) reaches 1.6 ATA. Which condition is the diver most at
risk for?
A) CNS Oxygen Toxicity
B) Nitrogen Narcosis
C) Hypothermia
ADCI Surface Supplied Mixed Gas Diver Certification
Exam QUESTIONS AND CORRECT DETAILED SOLUTIONS
WITH RATIONALES LATEST THIS YEAR (2026-2027)
A comprehensive 250-question practice exam for the ADCI Surface Supplied Mixed Gas Diver
Certification.
The questions are fully randomized and cover ADCI Standards, Mixed Gas Physiology (HPNS, O₂
Toxicity, DCS), Diving Physics, Decompression Theory, Equipment (Umbilicals, Helmets,
Chambers), Emergency Procedures, and Gas Mixtures.
1. A tender is preparing a diver for a mixed gas dive. According to ADCI standards regarding the
standby diver, which of the following is required for working dives below 100 FSW?
A) The standby diver must be suited up and breathing on the umbilical, ready for immediate
entry.
B) The standby diver must remain in the chamber.
C) A second dive team must be on-site.
D) The standby diver only needs to be wearing a wetsuit.
Correct Answer: A
Rationale: For depths below 100 FSW, ADCI requires the standby diver to be fully dressed and
breathing on the umbilical to allow for immediate deployment in an emergency .
, Page 2 of 128
2. A diver is using a Heliox mixture at 150 meters. He begins to exhibit tremors and severe
dizziness. What condition is most likely causing this?
A) Nitrogen Narcosis
B) High-Pressure Nervous Syndrome (HPNS)
C) Carbon Dioxide Toxicity
D) Oxygen Toxicity
Correct Answer: B
Rationale: HPNS is induced by high pressure, specifically in deep helium dives, causing tremors
and CNS disturbances .
3. The ADCI International Consensus Standards are recognized as best practices by which federal
agencies?
A) EPA and CDC only
B) OSHA, the U.S. Coast Guard, and the U.S. Army Corps of Engineers
C) NOAA and FEMA
D) The Department of Energy
Correct Answer: B
, Page 3 of 128
Rationale: ADCI standards are specifically cited by OSHA, the USCG, and the Army Corps of
Engineers for commercial diving compliance .
4. If a diver consumes gas at a rate of 2 cubic feet per minute (RMV) at the surface, what will the
consumption rate be at 99 FSW (4 ATA)?
A) 2 cfm
B) 4 cfm
C) 6 cfm
D) 8 cfm
Correct Answer: D
Rationale: Pressure increases from 1 ATA to 4 ATA (99ft). Surface consumption rate (2 cfm)
multiplied by 4 ATA equals 8 cfm.
5. A diver using a surface-supplied mixed gas system experiences a total loss of gas from the
panel. What is the primary piece of equipment that allows him to safely reach the surface?
A) The helmet demand regulator
B) The pneumofathometer hose
C) The bailout cylinder (EGS)
D) The hot water suit manifold
, Page 4 of 128
Correct Answer: C
Rationale: The Emergency Gas Supply (bailout bottle) provides an independent, redundant
breathing gas source to allow the diver to safely return to the surface or bell .
6. To qualify for the initial ADCI Mixed-Gas Diver certification card, what are the minimum dive
requirements?
A) 100 total working dives, any mix
B) 100 Air dives and 50 Mixed-Gas dives
C) 50 Air working dives and 10 Mixed-Gas HeO2 working dives
D) 25 Saturation dives
Correct Answer: C
*Rationale: ADCI requires documented proof of 50 Air working dives and 10 Mixed-Gas HeO2
working dives prior to certification .*
7. The partial pressure of Oxygen (PPO2) reaches 1.6 ATA. Which condition is the diver most at
risk for?
A) CNS Oxygen Toxicity
B) Nitrogen Narcosis
C) Hypothermia
