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FDNY C91 Supervision of Storage, Handling, and Use of
Hazardous Materials Practice Exam COMPLETE QUESTIONS
AND DETAILED SOLUTIONS LATEST UPDATE THIS YEAR-JUST
RELEASED
Summarized Exam Coverage – FDNY C91 Certificate of Fitness
About the Certificate: The C-91 Certificate of Fitness authorizes an individual to supervise the storage,
handling, and use of hazardous materials at a specific location in New York City . The certificate
holder must be on duty whenever hazardous materials are being used, handled, or stored .
Key Subject Areas :
I. General Responsibilities & Regulatory Framework
• Primary duties of the C-91 supervisor
• When the certificate holder must be on duty
• Application, renewal, fees (25application,25application,15 renewal, $5 for address
change/replacement)
• Validity period: 3 years
• Required documents (application form, letter of employment, two forms of ID)
• FDNY Public Certification Unit location and hours
II. Hazardous Materials Classification & Properties
• NFPA 704 hazard diamond (blue=health, red=flammability, yellow=reactivity)
• Class B fires (flammable liquids)
• Corrosives (Class 8), Oxidizers, Flammables, Water-reactive materials
• Signs of chemical instability (container bulging, leaking, fumes)
III. Storage & Handling Requirements
• Storage of incompatible chemicals separately
• Secondary containment purpose
• Flammable storage cabinets (approved)
• Ignition source separation (minimum 25 feet)
• Ventilation requirements (local exhaust/fume hoods)
• Bonding and grounding for flammable liquid transfers
IV. Safety & Emergency Procedures
• First action for leaking container: evacuate and secure area
• Required PPE for corrosives: safety glasses, gloves, apron
• Spill containment kit contents
• When to notify FDNY (explosion, fire, reportable leak)
• Fire extinguisher types (Class B for flammable liquids)
V. Hazard Communication
• SDS content and accessibility
• OSHA Hazard Communication Standard
• Required training: initial assignment and whenever new hazards introduced
VI. Administrative Requirements
• Inventory logs
• Renewal notice (90 days before expiration)
• Lost certificate replacement procedure
250 Randomized Questions (No Subtopic Labels)
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1. A facility stores multiple types of hazardous chemicals. A C91 certificate holder must be present on
the premises to provide direct supervision during which specific operational period?
A) Only when the facility is open for public business
B) Whenever hazardous materials are being used, handled, or stored at the licensed location
C) Only during the daytime shift from 8 AM to 5 PM
D) Only when new shipments of hazardous materials are being received
Answer: B – The FDNY requires that a certificate holder be on duty whenever hazardous materials are
being used, handled, or stored at the licensed location to ensure continuous oversight of hazardous
operations .
2. The NFPA 704 hazard diamond is posted on a storage tank. The blue (left) quadrant contains the
number 3. What does this specific rating indicate about the chemical's hazard level for human health?
A) The material is non-hazardous to human health
B) The material can cause temporary incapacitation or residual injury with brief exposure
C) The material is extremely hazardous and could cause death or major injury from brief exposure
D) The material is slightly hazardous and requires only minor PPE
Answer: B – In the NFPA 704 system, a health hazard rating of 3 indicates materials that can cause
temporary incapacitation or residual injury with brief exposure .
3. A supervisor notices that a container of hazardous material is starting to bulge outward and has
developed a small leak. What is the most immediate action the C91 supervisor should take according to
FDNY requirements?
A) Patch the container with tape and continue operations
B) Move the container to a different storage shelf
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C) Evacuate personnel and secure the area, then follow spill response procedures
D) Open the container to release internal pressure
Answer: C – Safety is the priority; evacuating and isolating the spill prevents exposure and further
hazards. A bulging container indicates chemical instability requiring immediate action .
4. A company is applying for a new C91 Certificate of Fitness. What is the current non-refundable
application fee that must be submitted to the FDNY with the application?
A) 15B)15B)25
C) 50D)50D)100
Answer: B – The application fee for the C91 certificate is $25, which is nonrefundable .
5. The office manager asks why secondary containment systems are required under the hazardous
materials storage area. What is the correct explanation for the function of these systems?
A) They provide additional storage capacity for hazardous materials
B) They capture spills and leaks from primary containers to prevent environmental contamination
C) They improve the chemical compatibility of stored materials
D) They replace the need for primary containers
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Answer: B – Secondary containment captures leaks or spills from primary containers, preventing
hazardous material leaks from spreading and causing environmental contamination or safety hazards .
6. A lab uses both acids and bases. What is the primary safety hazard that justifies storing these two
classes of chemicals in separate, segregated cabinets?
A) They can react exothermically, causing heat and splattering that may lead to burns or injuries
B) They naturally neutralize each other with no reaction byproducts
C) They become more stable when stored together
D) They have incompatible label colors that must be separated
Answer: A – Acid-base reactions are exothermic and can cause violent splattering, leading to burns or
injuries if uncontrolled .
7. An employee is transferring a flammable liquid from one container to another. Which specific
technique is required to prevent a static spark that could ignite the liquid?
A) Using rubber tubing only
B) Bonding and grounding the containers
C) Wearing wool gloves
D) Spreading water on the floor first
FDNY C91 Supervision of Storage, Handling, and Use of
Hazardous Materials Practice Exam COMPLETE QUESTIONS
AND DETAILED SOLUTIONS LATEST UPDATE THIS YEAR-JUST
RELEASED
Summarized Exam Coverage – FDNY C91 Certificate of Fitness
About the Certificate: The C-91 Certificate of Fitness authorizes an individual to supervise the storage,
handling, and use of hazardous materials at a specific location in New York City . The certificate
holder must be on duty whenever hazardous materials are being used, handled, or stored .
Key Subject Areas :
I. General Responsibilities & Regulatory Framework
• Primary duties of the C-91 supervisor
• When the certificate holder must be on duty
• Application, renewal, fees (25application,25application,15 renewal, $5 for address
change/replacement)
• Validity period: 3 years
• Required documents (application form, letter of employment, two forms of ID)
• FDNY Public Certification Unit location and hours
II. Hazardous Materials Classification & Properties
• NFPA 704 hazard diamond (blue=health, red=flammability, yellow=reactivity)
• Class B fires (flammable liquids)
• Corrosives (Class 8), Oxidizers, Flammables, Water-reactive materials
• Signs of chemical instability (container bulging, leaking, fumes)
III. Storage & Handling Requirements
• Storage of incompatible chemicals separately
• Secondary containment purpose
• Flammable storage cabinets (approved)
• Ignition source separation (minimum 25 feet)
• Ventilation requirements (local exhaust/fume hoods)
• Bonding and grounding for flammable liquid transfers
IV. Safety & Emergency Procedures
• First action for leaking container: evacuate and secure area
• Required PPE for corrosives: safety glasses, gloves, apron
• Spill containment kit contents
• When to notify FDNY (explosion, fire, reportable leak)
• Fire extinguisher types (Class B for flammable liquids)
V. Hazard Communication
• SDS content and accessibility
• OSHA Hazard Communication Standard
• Required training: initial assignment and whenever new hazards introduced
VI. Administrative Requirements
• Inventory logs
• Renewal notice (90 days before expiration)
• Lost certificate replacement procedure
250 Randomized Questions (No Subtopic Labels)
, Page 2 of 128
1. A facility stores multiple types of hazardous chemicals. A C91 certificate holder must be present on
the premises to provide direct supervision during which specific operational period?
A) Only when the facility is open for public business
B) Whenever hazardous materials are being used, handled, or stored at the licensed location
C) Only during the daytime shift from 8 AM to 5 PM
D) Only when new shipments of hazardous materials are being received
Answer: B – The FDNY requires that a certificate holder be on duty whenever hazardous materials are
being used, handled, or stored at the licensed location to ensure continuous oversight of hazardous
operations .
2. The NFPA 704 hazard diamond is posted on a storage tank. The blue (left) quadrant contains the
number 3. What does this specific rating indicate about the chemical's hazard level for human health?
A) The material is non-hazardous to human health
B) The material can cause temporary incapacitation or residual injury with brief exposure
C) The material is extremely hazardous and could cause death or major injury from brief exposure
D) The material is slightly hazardous and requires only minor PPE
Answer: B – In the NFPA 704 system, a health hazard rating of 3 indicates materials that can cause
temporary incapacitation or residual injury with brief exposure .
3. A supervisor notices that a container of hazardous material is starting to bulge outward and has
developed a small leak. What is the most immediate action the C91 supervisor should take according to
FDNY requirements?
A) Patch the container with tape and continue operations
B) Move the container to a different storage shelf
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C) Evacuate personnel and secure the area, then follow spill response procedures
D) Open the container to release internal pressure
Answer: C – Safety is the priority; evacuating and isolating the spill prevents exposure and further
hazards. A bulging container indicates chemical instability requiring immediate action .
4. A company is applying for a new C91 Certificate of Fitness. What is the current non-refundable
application fee that must be submitted to the FDNY with the application?
A) 15B)15B)25
C) 50D)50D)100
Answer: B – The application fee for the C91 certificate is $25, which is nonrefundable .
5. The office manager asks why secondary containment systems are required under the hazardous
materials storage area. What is the correct explanation for the function of these systems?
A) They provide additional storage capacity for hazardous materials
B) They capture spills and leaks from primary containers to prevent environmental contamination
C) They improve the chemical compatibility of stored materials
D) They replace the need for primary containers
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Answer: B – Secondary containment captures leaks or spills from primary containers, preventing
hazardous material leaks from spreading and causing environmental contamination or safety hazards .
6. A lab uses both acids and bases. What is the primary safety hazard that justifies storing these two
classes of chemicals in separate, segregated cabinets?
A) They can react exothermically, causing heat and splattering that may lead to burns or injuries
B) They naturally neutralize each other with no reaction byproducts
C) They become more stable when stored together
D) They have incompatible label colors that must be separated
Answer: A – Acid-base reactions are exothermic and can cause violent splattering, leading to burns or
injuries if uncontrolled .
7. An employee is transferring a flammable liquid from one container to another. Which specific
technique is required to prevent a static spark that could ignite the liquid?
A) Using rubber tubing only
B) Bonding and grounding the containers
C) Wearing wool gloves
D) Spreading water on the floor first
