NICET Special Hazards II flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

NFPA 2001 scope

Standard on clean agent fire extinguishing systems. Covers design, installation, operation, testing, and maintenance of total flooding and local application systems using halocarbon and inert gas agents.

Clean agent design concentration

The agent concentration in air that extinguishes the hazard, plus a safety factor. NFPA 2001 requires the greater of the listed minimum design concentration or the cup burner extinguishing value times 1.2 for Class B fuels.

Inert gas agent equation

Inert gas quantity uses the volume-displacement form with a k-factor from the agent's specific volume. Halocarbon agents use a different vapor density form; the two equations are not interchangeable.

Enclosure hold time

The period the design concentration must be maintained after discharge, typically 10 minutes for occupied spaces. Verified by a door fan enclosure integrity test at acceptance and after enclosure changes.

Water mist classification

NFPA 750 classifies water mist by application: residential, light hazard, ordinary hazard, and special applications. Each class sets distinct discharge density, nozzle spacing, and pressure criteria.

Wet chemical system use

NFPA 17A systems protect commercial cooking equipment. A potassium-based agent saponifies animal and vegetable fats, forming a foam blanket that cools and smothers the cooking media.

Dry chemical system use

NFPA 17 systems use dry chemical agents such as sodium bicarbonate or monoammonium phosphate for flammable liquid and gas hazards. Monoammonium phosphate is rated for Class A, B, and C hazards.

Total flooding agent quantity

Computed from enclosure volume, design concentration, and agent density. Volume is corrected for permanent openings and solid obstructions that reduce the effective protected volume.

Cross-zoned detection

Two independent detectors or zones must alarm before discharge. A single detector alarm typically activates only the pre-discharge alarm and annunciation, reducing false discharges.

Pre-discharge time delay

A minimum 30-second delay in occupied spaces allows occupant egress before agent release. The delay is adjustable but not eliminable, and the AHJ may approve alternatives.

Abort switch requirements

Located at the egress door, dedicated to aborting discharge, and resettable. It does not substitute for a manual pull station and must be clearly identified.

Manual release station

Required at each egress door from the protected space. Actuation causes immediate discharge without the pre-discharge time delay and must be clearly labeled.

Predischarge vs discharge alarm

Predischarge alarm sounds during the time delay with a distinct pattern. Discharge alarm sounds on agent release with a different audible and visual pattern so occupants can distinguish the two.

Smoke detector spacing

Spot-type smoke detectors on smooth ceilings use 30-foot nominal spacing per NFPA 72, reduced for joists and beams. Beam detectors follow their listing-specific spacing rules.

Supervisory vs alarm signal

A valve supervisory switch on the agent container is a supervisory condition, not an alarm. Supervisory and trouble signals must annunciate distinctly from alarm signals.

Releasing panel listing

The control panel must be listed for releasing service per NFPA 72. The sequence of operation must be documented and verified during acceptance testing.

Releasing circuit supervision

The releasing circuit must be supervised so a single fault does not prevent discharge. NFPA 72 requires Class A or equivalent supervision for most releasing circuit designs.

Agent piping calculation

Piping must follow the manufacturer's listed calculation method. The flow calculation is submitted with the design and verified against nozzle pressure limits.

Nozzle installation limits

Nozzles must be sized per the listed design and installed at the specified height and spacing. Deflector distance to the ceiling is manufacturer-specific and must be maintained.

Pipe material listing

Pipe and fittings must be materials listed for the specific agent. Some halocarbon listings prohibit galvanized or copper; using unlisted materials voids the listing.

Container weight check

Containers are weighed or pressure-checked at each inspection interval. A loss exceeding 5 percent of weight or pressure outside the listed range requires recharge or replacement.

Door fan integrity test

An enclosure integrity test that confirms the hold time. Required at acceptance and after enclosure changes to verify the design concentration is retained for the required period.

Discharge time limits

Clean agent discharge is typically 10 seconds or less for halocarbons and 60 seconds or less for inert gases. The flow test verifies agent quantity, discharge time, and nozzle pressures.

Enclosure pressure relief

Pressure relief venting is required where agent discharge can overpressurize the enclosure. Vent size is based on enclosure volume and the specific agent's expansion characteristics.

Pipe support spacing

Hangers and supports must be listed and spaced per the manufacturer's requirements and applicable NFPA support spacing. Supports must accommodate thermal expansion of the piping.

Post-discharge recharge

Requires replacing the agent, re-verifying container weight and pressure, and inspecting nozzles and piping for obstruction before the system returns to service.

Clean agent ITM standard

NFPA 25 does not cover clean agent systems. Inspection, testing, and maintenance follow NFPA 2001 Chapter 7 and manufacturer instructions, with annual system inspection and testing.

Container test intervals

Container hydrostatic testing and hose retest intervals are agent-specific and listed by the manufacturer. Verify the specific agent's interval rather than applying a single universal schedule.

Inspection record content

Records document agent quantity, container pressure, nozzle and piping condition, detection devices, alarms, and the releasing panel sequence test, signed by the inspector.

Impairment notification

Before taking a system out of service, notify the AHJ, the owner, and the alarm company, and post a tag at the panel and container identifying the impairment.

Impairment coordinator

The designated person responsible for tracking an impairment with a permit or tag system, restoring the system, and documenting the restoration in the record.

Simulated release test

Functional testing of the releasing panel by simulating detector activation to verify the time delay, abort function, and manual release without actually discharging agent.