CRSC · California Referenced Standards Code

How are filters prepared and exposed during the 3‑minute flame test

In plain terms: the CRSC requires that unused filters be mounted in a specified 21‑inch square duct, run at about 200 fpm airspeed, and be attacked with the prescribed burners for 3 minutes. Observers watch for flame or sparks and sensors record smoke; the measured smoke-area and any flame projection determine whether the filter is Class 1 or Class 2 under **§ 12-71-100**.

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Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

The State Fire Marshal test for air filters requires that filters be tested clean (unused) and installed in a specified test duct and frame, then exposed to yellow, wavering flames for 3 minutes while observations and smoke-density measurements are recorded. The apparatus dimensions, airflow, burner arrangement, observation points and the smoke-area thresholds used to classify the filter as Class 1 or Class 2 are set out in § 12-71-100.

The single most important rule: test the filter clean in the specified 21" square duct at ~200 fpm and expose it to the prescribed burners for 3 minutes — classification depends on flame projection and the measured smoke-area under the curve. § 12-71-100.

Requirements in detail

Test specimen preparation

  • The specimen must be clean (unused) — filters are not loaded with dust or service residue prior to the test. § 12-71-100(b)1.
  • If the filter uses an adhesive coating, the coating must meet a minimum flash point: 325°F (163°C) Cleveland open cup or higher. § 12-71-100(d).

Test apparatus (what the lab must set up)

  • The test duct and frame geometry, burners and instrumentation are prescribed; the filter goes in a metal frame near mid-length of the duct. Key equipment requirements are in § 12-71-100(a).

Decision‑relevant dimensions and values

Decision item Required/Value Why it matters Code Reference
Test duct cross-section 21 inches square Controls flow and visual observation area § 12-71-100(a)1
Test duct length 13 1/2 feet (4114 mm) Ensures downstream travel/observation distance § 12-71-100(a)1
Filter size (frame) 20 × 20 inches (nominal) The frame and specimen sizing specified in apparatus § 12-71-100(a)2
Observation windows Mica windows on both doors Permit observation of both faces and downstream duct § 12-71-100(a)2
Burners Two 1‑inch pipe elbows about 18 in from filter base; yellow, wavering flames Creates the prescribed flame attack § 12-71-100(a)3
Burner gas use ≈ 4 cubic feet of gas per minute (approx. 1,000 Btu/ft³) Expected fuel consumption to achieve flame character § 12-71-100(a)3
Air velocity ~200 linear feet per minute (measured at discharge) Simulates typical duct flow and affects flame/particle transport § 12-71-100(a)4
Flame exposure duration 3 minutes Primary exposure period for observations and smoke measurement § 12-71-100(b)1
Smoke measurement sampling Readings every 5 sec for first minute, every 10 sec for next 2 minutes; area under curve calculated Used to quantify smoke production for classification § 12-71-100(b)2‑3
Class 1 smoke threshold Area under curve < 1.5 in² (967 mm²) and no flames or sparks produced Pass = minimal smoke/flame § 12-71-100(c)1
Class 2 smoke threshold Area under curve ≤ 6.0 in² (3871 mm²); may burn moderately but must not project flames or extensive sparks beyond discharge Moderate burning allowed but limited projection and smoke § 12-71-100(c)2

Test method & observations

  • Install the filter in the metal frame near mid-length of the duct and close the access doors with mica windows for observation. § 12-71-100(a)2.
  • Adjust air velocity to approximately 200 fpm measured at the discharge end before running test. § 12-71-100(a)4.
  • Ignite the burners (two 1" elbows) located about 18 inches from the filter base to produce yellow, wavering flames and apply flames to the filter for 3 minutes while watching both faces for flame/sparks and recording smoke readings. § 12-71-100(a)3; (b)1‑3.
  • Record photoelectric (microammeter) readings at the prescribed intervals, plot the drop in light intensity vs. time and determine the area under the curve — that area is the quantitative smoke metric used for classification. § 12-71-100(b)2‑3.

Classification rules (how pass/fail is decided)

  • If the filter does not produce flames or sparks under the attack and the smoke-area is < 1.5 in², it is Class 1. § 12-71-100(c)1.
  • If the filter burns moderately or emits moderate smoke but does not project flames or extensive sparks beyond the discharge and the smoke-area is ≤ 6.0 in², it is Class 2. § 12-71-100(c)2.

Exceptions & special cases

  • Filters must be clean (unused) for the test; tests on soiled/loaded filters are outside § 12-71-100(b)1 and would not follow this protocol.
  • Adhesive coatings on filters are allowed only if their flash point meets the minimum 325°F (163°C, Cleveland open cup) requirement in § 12-71-100(d); lower-flash-point adhesives are not permitted under this standard.
  • The standard classifies only two classes (Class 1 and Class 2); anything producing smoke-area greater than 6.0 in² or projecting flames beyond the duct is outside the acceptable outcomes described and would fail the described acceptance. § 12-71-100(c).

Common mistakes

  • Testing a used or dust-loaded filter — the code explicitly requires clean (unused) specimens. Missing this invalidates the test protocol. § 12-71-100(b)1.
  • Incorrect air velocity — not setting ~200 fpm at discharge changes flame/particle transport and invalidates comparability. § 12-71-100(a)4.
  • Misplacing burners or using the wrong flame character (must be yellow, wavering from the specified elbows about 18 in from the filter) — this alters flame attack severity. § 12-71-100(a)3.
  • Failing to sample microammeter/photoelectric readings at the prescribed intervals (every 5 s first minute, then every 10 s) or calculating the area under the curve incorrectly. These specific sampling intervals are part of the measurement procedure. § 12-71-100(b)2‑3.
  • Overlooking adhesive flash-point requirements when the filter includes liquid adhesives. § 12-71-100(d).

Worked example — concrete scenario with numbers

Scenario: A manufacturer submits a nominal 20 × 20 in pleated filter (clean) for testing.

  1. Lab installs the filter in the metal frame located mid-length of the 21 in square duct that is 13.5 ft long. § 12-71-100(a)1‑2.
  2. Air velocity is adjusted to 200 fpm at the duct discharge and verified with an anemometer. § 12-71-100(a)4.
  3. Two 1‑inch pipe-elbow burners about 18 in from the filter are ignited to produce the prescribed yellow, wavering flames consuming ≈ 4 ft³/min gas. Flames are applied for 3 minutes. § 12-71-100(a)3; (b)1.
  4. Photoelectric readings are taken every 5 s during the first minute and every 10 s for minutes 2–3; the plotted area under the curve is calculated (planimeter/mathematical). § 12-71-100(b)2‑3.
  5. Suppose the area under the curve calculates 2.0 in², and observers note moderate burning on the filter surface but no flames or extensive sparks projecting beyond the duct discharge. Result: the unit meets Class 2 criteria because 2.0 in² ≤ 6.0 in² and projection limits are satisfied. § 12-71-100(c)2.

If instead the area were 1.2 in² and there were no flames or sparks, classification would be Class 1. § 12-71-100(c)1.

Related provisions

  • § 12-71-100 — Description of the test apparatus, method, smoke measurement and classification rules for air filters.
  • § 12-7A-4.7 — Under‑deck flame exposure procedures (uses a 3‑minute burner exposure for deck tests) — useful for understanding other 3‑minute exposures in CRSC test methods.
  • § 12-7A-4.7.3–4.7.5 — Conduct of tests, reporting and conditions of acceptance for under‑deck tests (3‑minute exposure + observation period).
  • § 12-7A-1.10 — Test report content requirements for related SFM test standards (useful for reporting expectations).

Code references

Grounded in the retrieved California Referenced Standards Code — click a citation to read the verbatim passage:

  • CRSC § 12-71 High relevance — show source text

    STATE FIRE MARSHAL

    DESCRIPTION OF TEST APPARATUS, METHOD AND CLASSIFICATION REQUIREMENTS FOR AIR FILTERS

    Sec. 12-71-100.

    (a) Test apparatus.

    1. The test duct, made of M.S. gage galvanized sheet metal reinforced with angle irons, is 21 inches square (13 548 mm [2] ) and 13 [1] / 2 feet (4114 mm) long.
    2. One end of the duct is tapered to the discharge of a variable-speed blower and the other end is open to discharge. A metal filter frame is provided near the middle of the length of the duct to receive one 20 by 20 inches (508 mm by 508 mm) (nominal) filter unit. Two tightfitting doors, located to permit access to the filter frame, are each provided with a mica window to permit observation of both faces of the filter and conditions in the duct downstream from the filter.
    3. Two 1-inch (25 mm) pipe elbows, about 18 inches (457 mm) from the base of the test filter, form gas burner outlets adjusted to provide yellow, wavering flames. The burners consume approximately 4 cubic feet (approximately 1,000 Btu/cubic feet) of gas per minute.
    4. With the filter in place the air velocity is adjusted to approximately 200 linear feet per minute as measured at the discharge end of the duct by an Alnor Velometer Anemometer.

    (b) Test method.

    1. Filters are tested clean, that is, unused. The flames are applied for 3 minutes during which time observations are made of both faces of the filter as to the downstream travel of flame or sparks and the density, duration and character of the products of combustion.

    2. Smoke density is measured as the drop in light intensity on a microammeter by means of photoelectric cell mounted a few inches below and about 12 inches (305 mm) inside the discharge end of the duct. The light source, stabilized for light intensity, is mounted 1 inch (25 mm) above the duct directly above the photoelectric cell. The microammeter readings are recorded every 5 seconds for the first minute and every 10 seconds for the next 2 minutes.

    3. The differences between these readings and the readings taken before the test are plotted against time (the scale being 40 μA and 40 seconds to the inch) with the resulting area under the curve being measured by use of a planimeter or calculated mathematically. This area is a measure of the smoke density produced during the test.

    (c) Classification. As a result of the tests, air filter units are classified as Class 1 or 2 as indicated below:

    1. Class 1 air filter units are those which, when clean, do not produce flames or sparks when attacked by flame and which develop areas under the smoke density curves that are less than 1.5 square inches (967 mm [2] ).
    2. Class 2 air filter units are those which, when clean, burn moderately when attacked by flame or emit moderate amounts of smoke or both. These units, although they may be consumed to some extent, do not project flames or extensive sparks that would ignite adjacent combustible materials beyond the discharge end of the duct during the test and do not develop areas under the smoke density curves that are more than 6.0 square inches (3871 mm [2] ).

    (d) Adhesive coatings. Liquid-adhesive coatings used on filters shall have a flash point of 325°F (163°C) Cleveland open cup tester, or higher.

  • CRSC § 436.5. High relevance — show source text

    DEPARTMENT OF HEALTH SERVICES

    Authority: Sections 102, 208 and 25811.

    Reference: Sections 102, 208 and 436.5.

    ALL HEALING ARTS X-RAY INSTALLATIONS

    Sec. 12-31C-101. All radiation shielding barriers in rooms and enclosures housing radiation machines shall comply with the mandatory standards and appendices in Report No. 35, “Dental X-RAY Protection”; Report 49, “Structural Shielding Design and Evaluation for Medical use of X-rays and Gamma Rays of Energies up to 10 MeV”; and Report No. 51, “Radiation Protection Design Guidelines for 0.1-100 MeV Particle Accelerator Facilities.” Published by the National Council on Radiation Protection and Measurements, 7910 Woodmont Avenue, Bethesda, Maryland 20814.

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    12-71 AIR FILTERS

    STANDARD 12-71-1

    STATE FIRE MARSHAL

    DESCRIPTION OF TEST APPARATUS, METHOD AND CLASSIFICATION REQUIREMENTS FOR AIR FILTERS

    Sec. 12-71-100.

    (a) Test apparatus.

    1. The test duct, made of M.S. gage galvanized sheet metal reinforced with angle irons, is 21 inches square (13 548 mm [2] ) and 13 [1] / 2 feet (4114 mm) long.
    2. One end of the duct is tapered to the discharge of a variable-speed blower and the other end is open to discharge. A metal filter frame is provided near the middle of the length of the duct to receive one 20 by 20 inches (508 mm by 508 mm) (nominal) filter unit. Two tightfitting doors, located to permit access to the filter frame, are each provided with a mica window to permit observation of both faces of the filter and conditions in the duct downstream from the filter.
    3. Two 1-inch (25 mm) pipe elbows, about 18 inches (457 mm) from the base of the test filter, form gas burner outlets adjusted to provide yellow, wavering flames. The burners consume approximately 4 cubic feet (approximately 1,000 Btu/cubic feet) of gas per minute.
    4. With the filter in place the air velocity is adjusted to approximately 200 linear feet per minute as measured at the discharge end of the duct by an Alnor Velometer Anemometer.

    (b) Test method.

    1. Filters are tested clean, that is, unused. The flames are applied for 3 minutes during which time observations are made of both faces of the filter as to the downstream travel of flame or sparks and the density, duration and character of the products of combustion.
  • CRSC § 12-7 High relevance — show source text
    1. Test Fixture. The test fixture shall be as described in SFM 12-7A-1, with the exception that the top soffit projection of the wall assembly fixture is modified to facilitate installation and removal of eave assemblies. Gypsum board (or equivalent) is used to create a noncombustible wall surface in the 4 x 8 ft. opening in the wall test fixture.
    2. Eaves assembly. Fit the eave assembly into the test module so that the horizontal surface of the assembly is 84 inches (2.1 m) from the top of the burner.
    3. Moisture content. Measure the moisture content of the wooden members of the assembly using a moisture meter (ASTM D4444), and for sheathing products, by methods outlined in ASTM D4442.
    4. Sealing. Seal the edges and ends with ceramic wool or comparable material to prevent flame penetration in these locations of the eave assembly.

    12-7A-3.8 Conduct of Tests.

    1. Airflow. The wall test shall be conducted under conditions of ambient airflow.

    2. Number of tests. Conduct the tests on three replicate eaves assemblies.

    3. Burner output verification. Without the eaves assembly in place, adjust the burner for 300 ± 15 kW output. Extinguish the burner.

    4. Burner positioning. Center the burner with respect to the width of the eaves wall assembly and 0.75 inch (20 mm) from the wall. The distance from the floor to the top of the burner shall be 12 inches (300 mm).

    5. Procedure.

    5.1. Ignition. Ignite the burner, controlling for a constant 300 ± 15 kW output. 5.2. Flame exposure. Continue the exposure until flame penetration of the eaves occurs or for a 10-minute period.

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    MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR WILDFIRE EXPOSURE

    5.3. Continued combustion. If penetration does not occur, continue observation for an additional 30 minutes or until all combustion has ceased.

    Note: An infrared thermometer has been found to be useful to detect the increase of temperature on the back side of the eaves and as an aid to identify the areas of potential combustion. 6. Observations. Note the time, location and nature of flame penetration.

    12-7A-3.9 Report. The report shall include a description of the eaves material, details of the construction of the eaves, moisture content of the framing and wood-based soffit elements as applicable, and point of flame penetration. Provide details on the time and reasons for early termination of the test.

    12-7A-3.10 Conditions of Acceptance. Should one of the three replicates fail to meet the Conditions of Acceptance, three additional tests may be run. All of the additional tests must meet the Conditions of Acceptance.

    1. Absence of flame penetration of the eaves or horizontal projection assembly at any time.
    2. Absence of structural failure of the eaves or horizontal projection subassembly at any time.
    3. Absence of sustained combustion of any kind at the conclusion of the 40-minute test.

    FIGURE 1 — EAVES TEST ASSEMBLY

  • CRSC § 9.5 High relevance — show source text

    1. The specimen shall be suspended vertically with its lower edge 2 inches (51 mm) above the top of a [3] / 8 inch (9.5 mm) diameter Bunsen Burner. The test shall be performed in a draft-free area.

    2. The flames from the burner shall be 4 inches (101 mm) long and shall be adjusted with sufficient air supply to eliminate any yellow flame tips but without any distinct inner blue cone.

    3. The specimen shall be exposed to the flame at each corner and at not less than one other point along the lower edge. Each exposure shall be of sufficient duration to determine if the material will ignite and continue to burn, but shall be not less than 20 seconds.

    4. The criteria for acceptance shall be as follows: (A) There shall be not more than intermittent flaming appreciably beyond the area exposed to the test flame. (B) Flame shall not reach the top of the specimen. (C) On removing the test flame there shall be not more than 1 second of after flaming except there may be nonprogressive flaming of short duration in areas of accumulated char which were directly exposed to the test flame.

    Section 12-7-502

    (a) Framed rigid combustible decorative material. Rigid combustible decorative material and assemblies of materials not more than [1] / 4 inch (6 mm) in thickness used for folding doors, room dividers, decorative screens and similar applications, and which are installed with all edges protected, shall conform to the following:

    1. All exposed edges shall be protected with frames of metal or other noncombustible material, or solid wood of minimum [1] / 4 inch (6 mm) dimension.

    2. The total square foot area of the material shall not exceed ten percent of that of the floor area of the room in which the material is installed.

    3. When tested as follows, flames shall not reach the top edge of the specimen. The test shall be conducted in a draft free area, on a specimen of the material 12 inches by 12 inches (305 mm by 305 mm) suspended at a 45-degree angle from the horizontal with the upper and lower edges in a horizontal plane. The test flame shall be 3 inches (76 mm) long from a Bunsen burner of approximately [1] / 2 -inch (13 mm) inside diameter with the air supply completely shut off. The burner shall be positioned so that its top is 1 inch (25 mm) vertically below a point on the lower surface of the test specimen, 1 inch (25 mm) up from its lower horizontal edge and midway between the inclined edges. The exposure to the test flame and the duration of test shall be for a period of 2 minutes.

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    12-7A MATERIALS AND CONSTRUCTION METHODS

    FOR EXTERIOR WILDFIRE EXPOSURE

    EXTERIOR WALL SIDING AND SHEATHING

    SFM STANDARD 12-7A-1

    12-7A-1.1 Application. The minimum design, construction and performance standards set forth herein for exterior wall siding and sheathing are those deemed necessary to establish conformance to the provisions of these regulations. Materials and assemblies that meet the performance criteria of this standard are acceptable for use as defined in California Building Standards Code.

  • CRSC § 0.5 High relevance — show source text

    ** The horizontal airflow, measured at a horizontal distance of 20 inches (0.5 m) from the edge of the wall assembly, shall not exceed 1.64 ft/s (0.5 m/s). 3. Placement of test frame. Prior to testing, and without the test specimen in place, position the frame assembly under the exhaust hood and set the gas burner for the prescribed level of output. 4. Placement of specimen. Once the burner output is verified, position the specimen holder assembly at the desired test location under the collection hood.

    1. Test specimen. Insert the test specimen into the frame assembly, sealing all edges with ceramic wool.
    2. Ignition. Simultaneously ignite the gas burner and start the timer marking the beginning of the test. Control the burner to a constant 150 ± 8 kW output. Control the hood duct flow to collect all products of combustion.
    3. Flame exposure. Continue the flame exposure until flame penetration of the test specimen and sustained flaming on the unexposed side occurs or for a period of 10 minutes, then extinguish the burner.
    4. Observation. If sustained flaming on the unexposed side of the test specimen has not occurred, observe the unexposed side of the test specimen for an additional 60 minutes for evidence of sustained flaming or glowing combustion on the unexposed side. Terminate the observation prior to the completion of the 60-minute observation period if all evidence of flame, glow and smoke has disappeared.

    Note: An infrared thermometer has been found to be useful to detect the increase of temperature on the unexposed side of the test assembly. 9. Documentation. Perform photographic and/or video documentation before, during and after each test.

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    12-7A-1.10 Report. The report shall include the following:

    1. Name and address of the testing laboratory.

    2. Name and address of test sponsor.

    3. Description of the test specimen including construction details of the wall system, including details of individual components (such as type, thickness and installation method of any sheathing) and the manufacturer’s installation details and limitations as applicable.

    4. Number of specimens tested.

    5. Description of weathering, as applicable.

    6. Moisture content of hygroscopic elements of wall system construction at the time of testing.

    7. Details of the burner verification, including heat supply rate.

    8. Date of test, test identification number and date of report.

    9. The test results shall include:

    9.1. A notation of the time and location of sustained flaming on the unexposed side of the test specimen during the test, along with the sequence number of the test specimen. 9.2. A determination of the presence of glow on the unexposed side of the test specimen at the end of the 60-minute observation period. 9.3. Observations of the burning characteristics of the exposed surface of the test wall during and after the flame

    exposure.

    12-7A-1.11 Conditions of Acceptance. Should one of the three replicates fail to meet the Conditions of Acceptance, three additional tests may be run. All of the additional tests must meet the Conditions of Acceptance.

    1. Absence of flame penetration through the wall assembly at any time.
    2. Absence of evidence of glowing combustion on the interior surface of the assembly at the end of the 70-minute test.
  • CRSC § 12-7 High relevance — show source text

    12-7A-4A.7.2 Test system preparation. See 12-7A-4 Figure No. 1.

    1. Deck support assembly. Assembly that holds the test deck over the burner.
    2. Baffle panels and joist support. Horizontal metal plates to support the deck joists along their full length, and also to confine burner flames to the underside of the deck boards located between the support joists.
    3. Back wall. Ceramic fiber board or another noncombustible panel product for the back wall material. Total height of the back wall is 8 feet (2.4 m).
    4. Ledger board. A 4-foot-long (1.2 m) simulated 2 x 6 ledger board shall be constructed of layers of ceramic fiber board (or other noncombustible panel product) and attached to the wall at a height slightly below the overhang of the rear deck board of the test deck.

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    12-7A-4A.7.3 Conduct of tests.

    1. Airflow. The test is conducted under conditions of ambient airflow.

    2. Number of tests. Conduct the test on three replicate assemblies.

    3. Burner output verification. Without a deck in the apparatus, set the output of the burner to 80 ± 4 kW. Conduct a verification run of 3 minutes to ensure the heat release rate, and then turn off the burner.

    4. Measurement of heat release rate. HRR is measured during the tests with a properly calibrated oxygen depletion calorimeter. Since HRR is typically a post-test analysis, this criterion for Acceptance may be determined at the end of the test.

    5. Burner positioning. Center the burner directly under the middle deck board, midway between the joists. The distance from the top of the burner to the bottom of the deck boards shall be 27 inches (690 mm).

    6. Moisture content. Measure the moisture content of the wooden members of the assembly using a moisture meter (ASTM D4444).

    7. Procedure.

    7.1. Ignition. Ignite the burner, controlling for a constant 80 ± 4 kW output. 7.2. Flame exposure. Continue the exposure for a 3-minute period. Extinguish the burner.

    7.3. Continued combustion. Continue observation for an additional 40 minutes or until all combustion has ceased. The test shall be terminated immediately if flaming combustion accelerates uncontrollably (runaway combustion) or structural failure of any deck board occurs. 8. Observations. Note physical changes of the deck boards during the test, including structural failure of any deck board, location of flaming and glowing ignition, and loss of material (i.e., flaming drops of particles falling from the deck). It is desirable to capture the entire test with a video recorder to allow review of the details of performance.

    12-7A-4A.7.4 Report. The report shall include a description of the deck board material and the time of any degradation (effective net peak heat release rate) during the test.

  • CRSC § 12-7 High relevance — show source text

    12-7A-4.7 PART A. Under-deck flame test.

    12-7A-4.7.1 Equipment.

    1. Burner. A 12 x 12 inch (300 x 300 mm) sand diffusion burner shall be used. Natural gas, methane or propane shall be supplied to the burner through a metered control system. The gas supply to the burner shall produce a net heat output of 80 ± 4 kW throughout the flame exposure. Burner output can be determined from HRR or calculated from the gas flow rate, temperature and pressure.
    2. Oxygen depletion calorimeter. The equipment shall include a hood, associated ducting and instrumentation to provide HRR data by oxygen depletion calorimetry.

    12-7A-4.7.2 Test system preparation. See Figure No. 1.

    1. Deck support assembly. The assembly that holds the test deck over the burner.
    2. Baffle panels and joist support. Horizontal metal plates to support the deck joists along their full length, and also to confine burner flames to the underside of the deck boards located between the support joists.
    3. Back wall. Ceramic fiber board or another noncombustible panel product for the back wall material. Total height of the back wall shall be 8 feet (2.4 m).

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    1. Ledger board. A 4-foot-long (1.2 m) simulated 2 x 6 ledger board shall be constructed of layers of ceramic fiber board (or other noncombustible panel product) and attached to the wall at a height slightly below the overhang of the rear deck board of the test deck.

    12-7A-4.7.3 Conduct of tests.

    1. Airflow. The test shall be conducted under conditions of ambient airflow.

    2. Number of tests. Conduct the test on three replicate assemblies.

    3. Burner output verification. Without a deck in the apparatus, set the output of the burner to 80 ± 4 kW. Conduct a verification run of 3 minutes to ensure the heat release rate, and then turn off the burner.

    4. Measurement of heat release rate. HRR is measured during the tests with a properly calibrated oxygen depletion calorimeter. Since HRR is typically a post-test analysis, this criterion for Acceptance may be determined at the end of the test.

    5. Burner positioning. Center the burner directly under the middle deck board, midway between the joists. The distance from the top of the burner to the bottom of the deck boards shall be 27 inches (690 mm).

    6. Moisture content. Measure the moisture content of the wooden members of the assembly using a moisture meter (ASTM D4444).

    7. Procedure.

    7.1. Ignition. Ignite the burner, controlling for a constant 80 ± 4 kW output. 7.2. Flame exposure. Continue the exposure for a 3-minute period. Extinguish the burner.

    7.3. Continued combustion. Continue observation for an additional 40 minutes or until all combustion has ceased.

  • CRSC § 12-7 High relevance — show source text
    1. When tested as follows, flames shall not reach the top edge of the specimen. The test shall be conducted in a draft free area, on a specimen of the material 12 inches by 12 inches (305 mm by 305 mm) suspended at a 45-degree angle from the horizontal with the upper and lower edges in a horizontal plane. The test flame shall be 3 inches (76 mm) long from a Bunsen burner of approximately [1] / 2 -inch (13 mm) inside diameter with the air supply completely shut off. The burner shall be positioned so that its top is 1 inch (25 mm) vertically below a point on the lower surface of the test specimen, 1 inch (25 mm) up from its lower horizontal edge and midway between the inclined edges. The exposure to the test flame and the duration of test shall be for a period of 2 minutes.

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    12-7A MATERIALS AND CONSTRUCTION METHODS

    FOR EXTERIOR WILDFIRE EXPOSURE

    EXTERIOR WALL SIDING AND SHEATHING

    SFM STANDARD 12-7A-1

    12-7A-1.1 Application. The minimum design, construction and performance standards set forth herein for exterior wall siding and sheathing are those deemed necessary to establish conformance to the provisions of these regulations. Materials and assemblies that meet the performance criteria of this standard are acceptable for use as defined in California Building Standards Code.

    12-7A-1.2 Scope. This standard evaluates the performance of exterior walls of structures when exposed to direct flames.

    12-7A-1.3 Referenced documents.

    1. ASTM E2257, Test Method for Room Fire Test of Wall and Ceiling Materials and Assemblies.

    2. ASTM D4442, Test Methods for Direct Moisture Content Measurement of Wood and Wood-Base Materials.

    3. ASTM D4444, Test Methods for Use and Calibration of Hand-Held Moisture Meters.

    4. California Building Code, Chapter 7A.

    12-7A-1.4 Definitions.

    1. Siding (cladding). Any material that constitutes the exposed exterior covering of an exterior wall and is applied over sheathing or is directly attached to the wall structural system.
    2. Sheathing. The material placed on an exterior wall beneath cladding or siding and is directly attached to the wall structural system.

    12-7A-1.5 Summary of test method.

    1. Direct flame exposure. This test method provides for the direct flame exposure of a wall specimen to a flame source centered at the base of a 4-foot by 8-foot (1220 mm by 2440 mm) test assembly.
    2. Gas burner. The method employs a gas burner to produce a diffusion flame in contact with the test wall assembly.
    3. Heat output. The gas burner produces a prescribed net rate of heat output of 8535 Btu/min (150 kW) for a period of 10 minutes, after which the flame exposure is terminated.
    4. Resistance to fire penetration. The test method measures the ability of the wall system to resist fire penetration from the exterior to the unexposed side of the test assembly under the conditions of exposure.
  • CRSC § 7.1. High relevance — show source text
    1. Procedure.

    7.1. Ignition. Ignite the burner, controlling for a constant 80 ± 4 kW output. 7.2. Flame exposure. Continue the exposure for a 3-minute period. Extinguish the burner.

    7.3. Continued combustion. Continue observation for an additional 40 minutes or until all combustion has ceased.

    1. Observations. Note physical changes of the deck boards during the test, including structural failure of any deck board, location of flaming and glowing ignition, and loss of material (i.e., flaming drops of particles falling from the deck). It is desirable to capture the entire test with a video recorder to allow review of the details of performance.

    12-7A-4.7.4 Report. The report shall include a description of the deck board material and the time of any degradation (effective net peak heat release rate, structural failure, flaming drops or particles falling from the deck) during the test.

    1. Calculated rate of heat release. The effective net peak heat release rate (HRR) shall be calculated as follows: 1.1. During the first 5 minutes of the test (the 3 minutes during which the ignition source burner is operating and the immediately following 2 minutes) the effective net peak HRR of the test assembly shall be reported as: effective net peak HRR = (peak heat release rate – 80 kW) / (deck surface area). 1.2. During the remaining test duration the effective net peak heat release rate of the test assembly shall be reported as: effective net peak HRR = (peak heat release rate) / (deck surface area).

    12-7A-4.7.5 Conditions of Acceptance. Should one of the three replicates fail to meet the Conditions of Acceptance, three additional tests may be run. All of the additional tests must meet the Conditions of Acceptance.

    1. Effective net peak heat release rate of less than or equal to 25 kW/ft [2] (269 kW/m [2] ).
    2. Absence of sustained flaming or glowing combustion of any kind at the conclusion of the 40-minute observation period.
    3. Absence of falling particles that are still burning when reaching the burner or floor.

    12-7A-4.8 PART B. Burning brand exposure.

    12-7A-4.8.1 Equipment.

    1. Wind tunnel. The wind tunnel shall have the capability of providing 12 mph (5.4 m/s) airflow over the deck assembly.
    2. Anemometer. Device for measuring airflow across the deck.
    3. Burner. Gas-fueled burner for brand ignition.

    12-7A-4.8.2 Test system preparation. See Figure 2. The ASTM E108 “A” brand roof test apparatus is to be used, with the following modifications:

    1. Deck support. The deck shall be supported horizontally with the center 60 inches (150 mm) from the front opening of the wind tunnel and the joists parallel to the airflow and resting on two transverse metal supports. The top surfaces of these supports, no more than 3 inches (75 mm) wide, are at the same height as the floor of the wind tunnel.
    2. Fragments. Burning fragments shall be free to fall to the floor of the room.

    12-7A-4.8.3 Conduct of tests.

    1. Number of tests. Conduct the test on three replicate assemblies.
    2. **Moisture content.
  • California Referenced Standards Code High relevance — show source text

    (f) Mineral aggregate in board form.

    1. Composition. The basic material shall be mineral in nature, crushed, dried and graded to the proper particle size and expanded by the application of heat to form a spherical, cellular type of aggregate. It shall be composed of spherical cellular beads of expanded aggregate and fibers formed into rigid, flat, rectangular units and shall have an integral water proofing

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    STANDARDS FOR INSULATING MATERIAL

    treatment. It shall be clean, dry and free of extraneous material. Fibers shall be evenly distributed and insulation and facings shall be sufficiently coherent to be unaffected by handling and installation. 2. Thermal performance. Determination of the thermal performance shall be in accordance with ANSI/ASTM C177-76, ANSI/ASTM C236-66 or ANSI/ASTM C518-76 at the manufacturer’s option. 3. Resistance to combustion. Surface-burning characteristics of materials with facings and membranes intended for exposed applications shall be determined according to ANSI/ASTM E84-79 and shall not exceed the following values:

    Flame spread. . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Smoke developed. . . . . . . . . . . . . . . . . . . . . . 450 Facings and membranes of materials intended for exposed applications shall be exposed to the flame during the ANSI/ASTM E84-79 test.

    Insulation boards exclusive of facings and membranes shall not exceed the following values:

    Flame spread. . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Smoke developed. . . . . . . . . . . . . . . . . . . . . . . 50 (g) Mineral fiber in blanket form.

    1. Composition. The basic material shall be fibers made from mineral substances such as rock, slag or glass processes from a molten state into fibrous form.

    2. Thermal performance. Determination of the thermal performance shall be in accordance with ANSI/ASTM C177-76, ANSI/ASTM C236-66 or ANSI/ASTM C518-76 at the manufacturer’s option.

    3. Size. The thickness shall be determined according to ANSI/ASTM C167-64.

    4. Resistance to combustion. Surface-burning characteristics of materials with facings and membranes intended for exposed applications shall be determined according to ANSI/ASTM E84-79 and shall not exceed the following values:

    Flame spread. . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Smoke developed. . . . . . . . . . . . . . . . . . . . . . 450 Facings and membranes of materials intended for exposed applications shall be exposed to the flame during the ANSI/ASTM E84-79 test.

    Insulation blankets not intended for exposed applications shall comply with the United States General Services Administration insulation standard HH-I-521F dated September 4, 1980, for flammability and smoldering combustion testing. 5. Corrosiveness. Corrosiveness shall be determined according to Test Description Number 2. The steel test plate in contact with the insulation shall show no greater corrosion than a steel plate in contact with sterile cotton. 6.

  • CRSC § 8-5 Medium relevance — show source text

    (1) Test specimen shall be 12 inches wide and 24 inches long. Four specimens shall be tested, two in each direction of the material. (2) The specimen shall be suspended vertically with its lower edge 2 inches above the top of a [3] / 8 inch diameter Bunsen Burner. The test shall be performed in a draft-free area.

    (3) The flames from the burner shall be 4 inches long and shall be adjusted with sufficient air supply to eliminate any yellow flame tips but without any distinct inner blue cone.

    (4) The specimen shall be exposed to the flame at each corner and at not less than one other point along the lower edge. Each exposure shall be of sufficient duration to determine if the material will ignite and continue to burn, but shall be not less than 20 seconds.

    (5) The criteria for acceptance shall be as follows:

    (A) There shall be not more than intermittent flaming appreciably beyond the area exposed to the test flame.

    (B) No flame shall reach the top of the specimen.

    (C) On removing the test flame there shall be not more than one second of after flaming except there may be nonprogressive flaming of short duration in areas of accumulated char which were directly exposed to the test flame.

    (b) Framed Rigid Combustible Decorative Material. Rigid combustible decorative material and assemblies of materials not more than 1 / 4 inch in thickness used for folding doors, room dividers, decorative screens and similar applications, and which are installed with all edges protected, shall conform to the following: (1) All exposed edges shall be protected with frames of metal or other noncombustible material, or solid wood of minimum [1] / 4 inch dimension.

    (2) The total square foot area of the material shall not exceed ten percent of that of the floor area of the room in which the material is installed.

    (3) When tested as follows, no flames shall reach the top edge of the specimen.

    The test shall be conducted in a draft free area, on a specimen of the material 12 inches by 12 inches suspended at a 45 degree angle from the horizontal with the upper and lower edges in a horizontal plane. The test flame shall be 3 inches long from a Bunsen Burner of approximately [1] / 2 inch inside diameter with the air supply completely shut off. The burner shall be so positioned so that its top is 1 inch vertically below a point on the lower surface of the test specimen, 1 inch up from its lower horizontal edge, and mid-way between the inclined edges. The exposure to the test flame and the duration of test shall be for a period of 2 minutes.

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    INTERIOR FINISH, DECORATIVE MATERIALS AND FURNISHINGS

    803.5.1 Room corner test for textile wall coverings and expanded vinyl wall coverings. Textile wall coverings and expanded vinyl wall coverings shall meet the criteria of Section 803.5.1.1 when tested in the manner intended for use in accordance with the Method B protocol of NFPA 265 using the product mounting system, including adhesive. Test specimen preparation and mounting shall be in accordance with ASTM E2404.

  • CRSC § 12-7 Medium relevance — show source text

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR WILDFIRE EXPOSURE

    12-7A-1.10 Report. The report shall include the following:

    1. Name and address of the testing laboratory.

    2. Name and address of test sponsor.

    3. Description of the test specimen including construction details of the wall system, including details of individual components (such as type, thickness and installation method of any sheathing) and the manufacturer’s installation details and limitations as applicable.

    4. Number of specimens tested.

    5. Description of weathering, as applicable.

    6. Moisture content of hygroscopic elements of wall system construction at the time of testing.

    7. Details of the burner verification, including heat supply rate.

    8. Date of test, test identification number and date of report.

    9. The test results shall include:

    9.1. A notation of the time and location of sustained flaming on the unexposed side of the test specimen during the test, along with the sequence number of the test specimen. 9.2. A determination of the presence of glow on the unexposed side of the test specimen at the end of the 60-minute observation period. 9.3. Observations of the burning characteristics of the exposed surface of the test wall during and after the flame

    exposure.

    12-7A-1.11 Conditions of Acceptance. Should one of the three replicates fail to meet the Conditions of Acceptance, three additional tests may be run. All of the additional tests must meet the Conditions of Acceptance.

    1. Absence of flame penetration through the wall assembly at any time.
    2. Absence of evidence of glowing combustion on the interior surface of the assembly at the end of the 70-minute test.

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    MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR WILDFIRE EXPOSURE

    EXTERIOR WINDOWS

    SFM STANDARD 12-7A-2

    12-7A-2.1 Application. Exterior window assemblies that meet the performance criteria of this standard are acceptable for use as defined in the California Building Standards Code.

    12-7A-2.2 Scope. This standard evaluates the performance of exterior windows used in structures when exposed to direct flames.

    12-7A-2.3 Referenced documents.

    1. AAMA (for definitions) Training Manual, Residential & Light Commercial Window and Door Installation Training and Registration Program.
    2. CAWM 400-95, Standard Practice for Installation of Windows with Integral Mounting Flange in Wood Frame Construction.

    12-7A-2.4 Definitions.

    1. Frame (Jambs). This usually consists of two vertical members (side jambs) and two horizontal members (head and sill) that hold the sash. Frames and sash are typically made of steel, aluminum, vinyl, fiberglass, wood or a combination of these materials.

    2. Glazing. The glass in a window. It may include layers of plastic as well as glass.

    3. Sash. The fixed or movable parts of the window in which the panes of glass are set.

    12-7A-2.5 Test apparatus.

    1. Wall assembly test module. The module is designed to permit rapid installation and removal of window/wall assemblies, and is designed to prevent edge penetration of fire at the margins.

Frequently asked questions

What does “tested clean” mean in this standard?

It means the filter must be unused (no loading or service residue) when tested — the protocol in § 12-71-100(b)1 requires clean specimens.

How long are flames applied to the filter?

Flames are applied for 3 minutes; during that time both faces are observed and smoke measurements recorded per § 12-71-100(b)1–3.

What smoke-area value separates Class 1 and Class 2?

< 1.5 in² area under the smoke-density curve is Class 1; ≤ 6.0 in² (with other limits on flame projection) is Class 2. See § 12-71-100(c).

Do adhesive coatings matter?

Yes — liquid adhesive coatings on filters must have a flash point of 325°F (163°C) Cleveland open cup or higher per § 12-71-100(d).

If a filter emits smoke but no flames beyond the duct, can it still pass?

Yes — a filter may be Class 2 if it burns moderately or emits moderate smoke but does not project flames or extensive sparks beyond the discharge and its smoke-area is ≤ 6.0 in². § 12-71-100(c)2.

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Related in the CRSC

How is smoke density recorded, plotted and quantified (area under the curve)

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Test method, timing, and smoke-density measurement

California Referenced Standards Code