STSC Fire Prevention and Protection in Construction 2 — Questions and Answers

Question 1: What does the 'fire triangle' represent in fire prevention?

Three types of fire extinguishers
The three elements needed for fire: fuel, oxygen, and heat/ignition source (Correct answer)
Three OSHA fire safety standards
Three categories of fire hazards

Correct answer: The three elements needed for fire: fuel, oxygen, and heat/ignition source

The fire triangle shows that fire requires fuel, oxygen, and heat — removing any one element extinguishes or prevents fire.

The fire triangle (now more accurately called the fire tetrahedron, which adds the chemical chain reaction) illustrates that fire requires three elements to exist: fuel (combustible material), oxygen (typically from air), and heat (ignition source). Fire prevention strategies focus on eliminating one or more of these elements: removing combustible materials (fuel), using inerting gases to displace oxygen, and controlling ignition sources (heat). Understanding this principle is fundamental to all fire prevention programs.

Question 2: Under OSHA 29 CFR 1926.150, portable fire extinguishers on construction sites must be inspected:

Only at the beginning of each project
At least monthly (Correct answer)
Annually by the manufacturer
After every use

Correct answer: At least monthly

OSHA requires that fire extinguishers be inspected monthly to ensure they are fully charged and operational.

OSHA 29 CFR 1926.150(c)(1)(viii) requires that portable fire extinguishers be inspected at least monthly. The inspection should verify: the extinguisher is in its designated location; the operating instructions are legible; the pressure gauge reads in the operable range; safety pins and tamper indicators are intact; and there is no obvious physical damage or clogging. Annual maintenance (more thorough) must also be performed by a qualified person.

Question 3: Which fire extinguisher class is rated for fires involving flammable liquids such as gasoline, diesel fuel, and solvents?

Class A
Class B (Correct answer)
Class C
Class D

Correct answer: Class B

Class B extinguishers are designed for flammable liquid fires — commonly found in construction where fuels, paints, and solvents are used.

Fire extinguisher classifications: Class A = ordinary combustibles (wood, paper, cloth, plastic); Class B = flammable liquids and gases (gasoline, diesel, oils, paints, solvents); Class C = energized electrical equipment; Class D = combustible metals (magnesium, titanium); Class K = cooking oils. Most construction sites use ABC dry chemical extinguishers that are effective on the three most common fire types. Dry chemical on a Class B fire works by interrupting the chemical chain reaction.

Question 4: Hot work permits are required for operations that produce sparks or flame because:

They are an OSHA record-keeping requirement
They ensure fire hazards are identified, combustibles removed, and fire watches are established before work begins (Correct answer)
They document equipment calibration
They are required by the fire marshal for all construction sites

Correct answer: They ensure fire hazards are identified, combustibles removed, and fire watches are established before work begins

Hot work permits create a systematic process to evaluate and control ignition hazards before welding, cutting, or grinding begins.

Hot work permits (required by NFPA 51B and often by OSHA under 29 CFR 1926.352) establish a control process for welding, cutting, grinding, and other spark-producing operations in areas with combustible materials. A permit system requires: fire hazard assessment before work begins; removal or protection of combustibles within 35 feet; availability of fire extinguishing equipment; a designated fire watch; and post-work monitoring for 30-60 minutes after work concludes. Hot work is a leading cause of construction fires.

Question 5: The minimum distance for placing a portable fire extinguisher from any hazard area is:

5 feet
10 feet (Correct answer)
25 feet
50 feet

Correct answer: 10 feet

OSHA requires that fire extinguishers be no more than 100 feet from a flammable liquid hazard and be placed within reach but not so close they are inaccessible during a fire.

OSHA 29 CFR 1926.150(c)(1)(vi) requires a fire extinguisher rated not less than 2A to be provided for each 3,000 square feet of the protected area. For Class B hazards (flammable liquids), a 10-BC rated extinguisher must be located within 50 feet of more than 5 gallons of flammable liquid. Extinguishers should be close enough to reach quickly but positioned so that a fire does not block access to the extinguisher.

Question 6: Temporary heating equipment used in construction must be positioned so that:

It faces north to improve efficiency
Combustible materials are kept at least 3 feet from the unit and the unit has a clearance from all surfaces (Correct answer)
Workers can stand directly next to it for warmth
It is connected to the permanent electrical system

Correct answer: Combustible materials are kept at least 3 feet from the unit and the unit has a clearance from all surfaces

Combustible materials must be kept at a safe distance from heaters to prevent ignition from radiant heat.

OSHA 29 CFR 1926.154 governs temporary heating devices on construction sites. Requirements include: maintaining a minimum clearance (typically 3 feet from combustibles but per manufacturer specifications); proper anchoring to prevent tip-over; using only listed/approved devices; providing adequate ventilation to prevent CO buildup; fuel storage in approved containers; and supervision when operating near combustible materials. Salamander-type heaters and propane heaters are common construction heat sources and require careful management.

STSC Fire Prevention and Protection in Construction 2

What does the 'fire triangle' represent in fire prevention?