CRSC · California Referenced Standards Code
Instrumentation, observation windows and where smoke density is measured
This explains where and how smoke density is measured for CRSC filter tests: use the 21" square, 13½ ft test duct with mica observation windows; mount the photoelectric cell about 12" inside the discharge end and the light 1" above; record microammeter readings at the specified intervals and compute the area under the curve to classify the filter under § 12‑71‑100.
Last reviewed: July 6, 2026
What the code requires — plain English
The California Referenced Standards Code requires a specific test duct, fixed instrumentation positions, and a defined method for measuring smoke density for air filter units. The controlling provision is § 12-71-100 . In short: filters are tested clean in a 21‑inch square, 13½‑ft long duct with mica observation windows, a specified photoelectric cell and light source located inside the discharge end of the duct, and smoke density is calculated from microammeter readings plotted against time to produce an area under the curve (the smoke density measure) .
The single most important rule: mount the photoelectric cell and light source exactly where the standard requires (a few inches below and about 12 inches (305 mm) inside the discharge end; light 1 inch above the duct), record microammeter readings at the specified intervals, and compute the area under the plotted curve per § 12-71-100 .
Requirements in detail
Test apparatus and observation windows (what must be built)
- Duct size: 21 inches square and 13½ feet (4114 mm) long. § 12-71-100 .
- Filter frame: accepts one 20 × 20 inches (508 × 508 mm) nominal filter unit, located near mid-length of the duct. § 12-71-100 .
- Doors & windows: two tight‑fitting doors, each fitted with a mica observation window to permit viewing of both faces of the filter and downstream duct conditions. § 12-71-100 .
- Burners: two 1‑inch pipe elbows ~18 inches (457 mm) from the base of the test filter; burners consume ~4 cubic feet/min gas. § 12-71-100 .
- Air velocity: adjust to approximately 200 linear feet per minute as measured at the discharge end (Alnor Velometer). § 12-71-100 .
Instrumentation and exact smoke‑meter placement
- Smoke sensor type / readout: smoke density is recorded as the drop in light intensity on a microammeter using a photoelectric cell. § 12-71-100 .
- Photoelectric cell location: mounted a few inches below and about 12 inches (305 mm) inside the discharge end of the duct (i.e., inside the duct, downstream). § 12-71-100 .
- Light source location: stabilized light source mounted 1 inch (25 mm) above the duct directly above the photoelectric cell. § 12-71-100 .
- Recording intervals: microammeter readings recorded every 5 seconds for the first minute and every 10 seconds for the next 2 minutes. § 12-71-100 .
- Data processing: plot differences from pretest readings vs. time using a plotting scale (the standard gives an example scale) and measure the resulting area under the curve (planimeter or calculation) — that area is the smoke density metric. § 12-71-100 .
Classification thresholds (decision rules)
- Class 1: area under the smoke density curve < 1.5 square inches (967 mm²). § 12-71-100 .
- Class 2: units that burn moderately or emit moderate smoke but do not develop areas under the smoke density curves greater than 6.0 square inches (3871 mm²) and do not project igniting sparks/flames beyond the duct. § 12-71-100 .
Quick reference table — decision‑relevant dimensions & values
| Parameter / decision dimension | Required value or location | Code Reference |
|---|---|---|
| Test duct cross-section | 21 in. square | § 12-71-100 |
| Duct length | 13½ ft (4114 mm) | § 12-71-100 |
| Test filter nominal size | 20 × 20 in. (508 × 508 mm) | § 12-71-100 |
| Observation windows | Mica, two doors permitting view of both faces + downstream | § 12-71-100 |
| Photoelectric cell position | a few inches below and ≈12 in (305 mm) inside discharge end | § 12-71-100 |
| Light source position | 1 in (25 mm) above duct directly above cell | § 12-71-100 |
| Microammeter recording cadence | Every 5 s (first 60 s); every 10 s (next 120 s) | § 12-71-100 |
| Plot scale (example) | 40 μA and 40 seconds to the inch (used to convert area under curve to sq in) | § 12-71-100 |
| Class 1 threshold | Area < 1.5 sq in | § 12-71-100 |
| Class 2 threshold | Area ≤ 6.0 sq in (must not be more than 6.0) | § 12-71-100 |
| Adhesive flash point (coatings) | ≥ 325°F (163°C) Cleveland open cup | § 12-71-100(d) |
Exceptions & special cases
- The standard applies to clean (unused) filter units; tests are conducted on new/unused filters as stated in the test method. Do not test used/loaded filters unless an alternate procedure is provided. § 12-71-100(b)(1) .
- Adhesive coatings on filters must meet a specific flash point (325°F / 163°C) to be acceptable. § 12-71-100(d) .
- The code gives the measurement method (photoelectric cell & microammeter, plotting and area measurement). Alternative instrumentation may be used only if it produces equivalent results and the light/receiver characteristics match the required response — if using an alternate system, document equivalence. (The standard explicitly prescribes the photoelectric arrangement and the plotting/area method for classification.) § 12-71-100 .
- The standard is narrowly written to classify air filter units; do not assume these placement details transfer unchanged to other fire tests — other CRSC standards address smoke measurement for rooms, ducts, or detectors (see Related provisions) .
Common mistakes
- Mounting the photoelectric cell too far from the specified ~12 in inside the discharge end, or placing it outside the duct — this invalidates the intended optical path and readings. § 12-71-100 .
- Failing to stabilize the light source or to mount it 1 in above the duct directly over the cell, causing inconsistent lamp flux. § 12-71-100 .
- Not recording the microammeter at the required cadence (5 s then 10 s intervals) or omitting the pretest baseline reading — timing and baseline are required to compute differences and area. § 12-71-100 .
- Forgetting to test clean (unused) filters, or using a loaded/dirty filter without a documented alternate method. § 12-71-100(b)(1) .
- Miscomputing the area under the curve by ignoring the plotting scale (the standard gives an example scale) or failing to use planimetry/mathematical integration as permitted. § 12-71-100(b)(3) .
Worked example — how to get the smoke‑density area (concrete numbers)
Setup per the standard: instrumented photoelectric cell a few inches below and 12 in (305 mm) inside the discharge end; stabilized light 1 in above the duct; microammeter baseline recorded just before ignition. See § 12-71-100 .
Sample (hypothetical) microammeter difference readings (μA) vs. time (s) after ignition:
- 0 s: 0 (baseline)
- 5 s: 10
- 10 s: 20
- 15 s: 25
- 20 s: 20
- 25 s: 15
- 30 s: 10
- 35 s: 5
- 40 s: 0 (then 50–120 s: 0)
Step 1 — compute the integral (area in μA·s). Using trapezoids for 0–40 s the summed area = 525 μA·s.
Step 2 — convert to square inches using the standard example plotting scale: 40 μA = 1 inch (vertical) and 40 s = 1 inch (horizontal), so 1 square inch = 40 μA × 40 s = 1600 μA·s (per § 12-71-100(b)(3) example). Therefore:
Area (sq in) = 525 / 1600 = 0.328 in².
Step 3 — classification: 0.328 in² < 1.5 in², so this test result would be Class 1 under § 12-71-100(c)(1) .
Note: the standard allows measuring the area by planimeter or by mathematical calculation; the worked example uses numeric integration, consistent with § 12-71-100(b)(3) .
Related provisions
- § 12-8-102 — Fire and smoke measurements and photographic record (room fire test smoke & CO measurements) .
- § 12-8-112 — Duct sampling locations and optical density measurement specifications used in larger-scale fire tests (optical density in ducts) .
- § 12-8-113 — Calibration and documentation requirements for ignition source and test equipment (calibration prior to tests) .
- § 12-72-100 — Test procedures for protective signaling systems; contains instrumentation and measurement requirements for detectors and smoke obscuration in detector sensitivity testing (context for detector test methods) .
- § 12-72-303 (f) — Describes the smoldering smoke source and detector response limits used in sensitivity testing of combustion products detectors (relevant to alternative smoke measurement approaches) .
If you need, I can extract the exact verbatim lines from § 12-71-100 (photographic excerpts) for use in a test protocol or create a step-by-step checklist for a test lab to follow that maps every instrument and measurement to the relevant clause in § 12-71-100 .
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.
- 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.
- 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.
- 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.
- 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.
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.
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.
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:
- 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] ).
- 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 § 1.5 High relevance — show source text
- 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.
- 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:
- 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] ).
- 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.
2025 CALIFORNIA REFERENCED STANDARDS CODE 107
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
108 2025 CALIFORNIA REFERENCED STANDARDS CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
12-72-1 PROTECTIVE SIGNALING SYSTEMS
STANDARD TEST PROCEDURES
STANDARD 12-72-1
STATE FIRE MARSHAL
SCOPE
Sec. 12-72-100.
(a) Basic. This standard represents the minimum basic requirements for the construction and performance of the protective signaling systems to be listed under this classification. The minimum design, construction and performance standards set forth herein are those deemed as minimum necessary to establish conformance to the regulations of the State Fire Marshal as set forth in the California Electrical Code, and when applicable shall be reported on in their entirety by the approved testing laboratory.
(b) Systems. This standard covers electrically operated devices and control units designed to transmit and sound alarms, supervisory and trouble signals to be employed in ordinary indoor locations in accordance with the Standards of the National Fire Protection Association for the Installation, Maintenance and Use of Proprietary, Auxiliary and Local Protective Signaling Systems, Remote Station, Nos. 72A, 72B, 72C and 72D, and the California Electrical Code. This includes combination protective signaling systems employing nonsupervised sounding circuits; combination fire alarm-communication, -program and -clock systems (hereinafter referred to as combination signaling systems); and audible devices used for both alarm and program or communication
purposes.
CRSC § 1.5 High relevance — show source text
The wick end is to be cut square and smoldering initiated by momentarily placing the wick end over a horizontally mounted resistive heater element energized to a dull red color. Smoldering may be promoted by passing a slow current of air over the wick end. The smoldering end is to be cut away approximately [1] / 4 inch (6 mm) above the charred section prior to conducting a succeeding trial. The smoldering rate of the wick is to be such that the visible smoke obscuration increases at an approximate uniform rate of 1.5 ± 0.2 percent per foot (0.0329 0.001 optical density per foot).
(g) Test equipment and methods.
- The visible smoke obscuration (optical density) in the test compartment is to be measured by means of a direct current (DC) type microammeter having a maximum internal resistance of 100 ohms used with a barrier type selenium photovoltaic cell, enclosed in a hermetically sealed case. The meter and cell are used in conjunction with the light produced by a tungsten filament automotive type lamp rated 6 volts and energized from a regulated supply to provide a light beam of uniform flux density. The photoelectric cell and lamp are to be spaced 5 feet (1524 mm) apart. The following equations are to be used: A. At any distance, the percent obscuration per foot will be: O u = [1 – ( T s /T c ) [1] [/d] ] 100
where:
O u = Percent obscuration per foot.
T s = Smoke density meter reading with smoke.
- Figure in parentheses denotes optical density per foot.
- A meter suitable for this purpose is Weston Instrument Model 622 in conjunction with a Model 594 RR Photronic Cell.
2025 CALIFORNIA REFERENCED STANDARDS CODE 143
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
PROTECTIVE SIGNALING SYSTEMS
T c = Smoke density meter reading with clear air.
d = Distance in feet (m × 3.33). B. The percent obscuration of light for the full length beam at any distance will be:
O d = [1 – ( T s /T c )] 100
where:
O d = Percent obscuration at distance d .
T s = Smoke density meter reading with smoke.
T c = Smoke density meter reading with clean air. C. When the percent obscuration per foot is known, the percent obscuration for the full length of any longer beam can be determined by the following: O d = [1 – [1 – ( O u /100)] [d] ] 100
where:
O d = Percent obscuration at distance d . O u = Percent obscuration per foot.
d = Distance in feet (m × 3.33).
D. At any distance, the total optical density will be:
OD t = Logo 10 ( T c /T s )
where:
OD t = Optical density.
T c = Smoke density meter reading with clear air.
T s = Smoke density meter reading with smoke. E. At any distance, the optical density per foot will be:
CRSC § 3.33 High relevance — show source text
2025 CALIFORNIA REFERENCED STANDARDS CODE 143
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
PROTECTIVE SIGNALING SYSTEMS
T c = Smoke density meter reading with clear air.
d = Distance in feet (m × 3.33). B. The percent obscuration of light for the full length beam at any distance will be:
O d = [1 – ( T s /T c )] 100
where:
O d = Percent obscuration at distance d .
T s = Smoke density meter reading with smoke.
T c = Smoke density meter reading with clean air. C. When the percent obscuration per foot is known, the percent obscuration for the full length of any longer beam can be determined by the following: O d = [1 – [1 – ( O u /100)] [d] ] 100
where:
O d = Percent obscuration at distance d . O u = Percent obscuration per foot.
d = Distance in feet (m × 3.33).
D. At any distance, the total optical density will be:
OD t = Logo 10 ( T c /T s )
where:
OD t = Optical density.
T c = Smoke density meter reading with clear air.
T s = Smoke density meter reading with smoke. E. At any distance, the optical density per foot will be:
OD f = [Logo 10 ( T c /T s )]/ d
where:
OD f = Optical density per foot.
T c = Smoke density meter reading with clear air.
T s = Smoke density meter reading with smoke.
d = Distance in feet (m × 3.33). 2. A meter [3] calibrated in volts is to be used to measure the relative buildup of primarily invisible products of combustion. The meter, used with an ionization detecting monitoring head without an alarm indicating circuit, has Americium 241 as the radioactive element. The monitoring head is to be located in the test chamber adjacent to the sample under test 3. Test chamber. The following items refer to Figure 12-72-3-1. A. Cabinet. Plywood, [ 3] / 4 inch (19 mm) thick, except for [1] / 4 inch (6 mm) thick clear plastic front panel. Overall dimensions approximately 69 [1] / 2 inches (1765 mm) long, 18 inches (457 mm) high, 11 inches (279 mm) deep. A center divider forms two equal 8 inches (203 mm) high by 10 inches (254 mm) deep interior compartments. Inside of lower left side of plastic front panel, as well as all interior surfaces of the cabinet are to be painted flat black. Plastic front assembled with rubber gasket. B. Combustible. Cotton wick. See Section 12-72-303 (f), Item 2. Secured by alligator type clip to removable cap which covers a 3 [1] / 4 -inch (82 mm) diameter hole in top of compartment. Cap measures approximately 4 inches square (2580 mm [2] ).
CRSC § 12-72 Medium relevance — show source text
- The operation of any manual switching part of a detector unit to other than its normal position while the detector unit is in the normal standby condition shall be indicated by a trouble signal, if the off-normal position of the switch interferes with normal operation of the detector unit.
- To determine if a detector unit complies with the requirements for electrical supervision, see Section 12-72-303 (d). The detector is to be tested with the representative system combination in its normal supervisory condition, and the type of fault to be detected is then to be introduced. Each fault shall be applied separately, the results noted and the fault removed. The system combination is then to be restored to its normal supervisory condition prior to establishing the next fault.
(f) Sensitivity test.
- A combustion products detector shall operate within the limits specified below when subjected to a smoldering smoke condition using the combustion products and test equipment described in the following paragraphs. If the detector employs a variable sensitivity setting, test measurements are to be made at maximum, minimum and nominal settings.
A. Visible Smoke Obscuration Limits—
0.0 percent per foot maximum (0.013) [1]
0.2 percent per foot minimum (0.001) [1]
B. Relative Combustion Products Measurement Limits—
9.0 volts maximum
1.0 volt minimum
C. Monitoring Means— Within 25 percent of the operating limits of the detector rating. 2. Combustion products. A mercerized cotton lamp wick, nominally [7] / 8 inch (22 mm) wide by [1] / 8 inch (3 mm) in cross section and secured by an alligator type clip 3 inches (76 mm) below a removable cover assembly is to be employed as the source of combustion products. The wick end is to be cut square and smoldering initiated by momentarily placing the wick end over a horizontally mounted resistive heater element energized to a dull red color. Smoldering may be promoted by passing a slow current of air over the wick end. The smoldering end is to be cut away approximately [1] / 4 inch (6 mm) above the charred section prior to conducting a succeeding trial. The smoldering rate of the wick is to be such that the visible smoke obscuration increases at an approximate uniform rate of 1.5 ± 0.2 percent per foot (0.0329 0.001 optical density per foot).
(g) Test equipment and methods.
- The visible smoke obscuration (optical density) in the test compartment is to be measured by means of a direct current (DC) type microammeter having a maximum internal resistance of 100 ohms used with a barrier type selenium photovoltaic cell, enclosed in a hermetically sealed case. The meter and cell are used in conjunction with the light produced by a tungsten filament automotive type lamp rated 6 volts and energized from a regulated supply to provide a light beam of uniform flux density. The photoelectric cell and lamp are to be spaced 5 feet (1524 mm) apart. The following equations are to be used: A. At any distance, the percent obscuration per foot will be: O u = [1 – ( T s /T c ) [1] [/d] ] 100
where:
O u = Percent obscuration per foot.
T s = Smoke density meter reading with smoke.
CRSC § 6.1 Medium relevance — show source text
d
(pcf)|MINIMUM COMPRES-
SIVE STRENGTH PER
SECTION BK106.6.1
(psi)|WALL-TYPE
REINFORCEMENT
PER TABLE
BK105.3|MINIMUM
THICKNESSc, e, f AT
TOP OF WALL
(inches)|MINIMUM
THICKNESSc, e, f AT
BOTTOM OF WALL
(inches)**| |1,200|100|85|E|9|12| |475|≥ 50 pcf: less than
40 inches from top of wall|40b|E or F|8|12| |475|≥ 70 pcf: from 40 inches to 80
inches from top of wall|55b|55b|55b|55b| |475|≥ 90 pcf: more than 80 inches
from top of wall|85|85|85|85| |Nonload bearing|50 to 100|≥ 60 psi
< 60 psib|E or F|9|9| |For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound = 0.45 kg, 1 pound per cubic foot = 16.02 kg/m3.
a.
Density is to be measured at equilibrium moisture content. Average wall density shall be within ±5 pcf of the tabulated value.
b.
Requires an approved engineered design per Section BK106.6.
c.
Cob thickness only. The interior and exterior cob faces shall be permitted to be unfinished or receive any plaster finish allowed by this appendix.
d.
Cob walls with more than one density shall be built with heavier densities below lighter densities.
e.
Minimum cob wall thickness shall be whichever is greater in Tables BK105.3, BK106.11(1) and BK108.1.
f.
Wall thicknesses less than 10 inches require an engineered design.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound = 0.45 kg, 1 pound per cubic foot = 16.02 kg/m3.
a.
Density is to be measured at equilibrium moisture content. Average wall density shall be within ±5 pcf of the tabulated value.
b.
Requires an approved engineered design per Section BK106.6.
c.
Cob thickness only. The interior and exterior cob faces shall be permitted to be unfinished or receive any plaster finish allowed by this appendix.
d.
Cob walls with more than one density shall be built with heavier densities below lighter densities.
e.
Minimum cob wall thickness shall be whichever is greater in Tables BK105.3, BK106.11(1) and BK108.1.
f.
Wall thicknesses less than 10 inches require an engineered design.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound = 0.45 kg, 1 pound per cubic foot = 16.02 kg/m3.
a.
Density is to be measured at equilibrium moisture content.CRSC § 7-1 Medium relevance — show source text
Note: See State Fire Marshal (SFM) 7-1 and Uniform Building Code (UBC) Standard 8-1.
This standard can be used to evaluate the effectiveness of thermal barriers in restricting the contribution of combustible materials in the wall and floor assemblies to fire growth in a padded safety cell. This standard shall be used in conjunction with ASTM E603-77, “Standard Guide for Room Fire Experiments,” which covers instrumentation, safety precautions and the general effect of various parameters.
(b) Tests and listings by approved testing agency. Test data for wall and/or ceiling materials or assemblies investigated and tested in accordance with the Standard for Safety established by Underwriters Laboratories, Inc., UL 723C, “Investigation for the Classification of Wall and Ceiling Interior Finish Materials and Assemblies Using a Room Fire Test,” will be acceptable for evaluation against this standard, provided all instrumentation data required by this standard is incorporated in the test and report.
(c) Test simulation. The test simulates a fire in the comer of an 8-foot by 12-foot (2438 mm by 3657 mm) compartment containing a single open doorway; this can be used to evaluate the relative performance of specific wall, ceiling and floor materials or assemblies when they are used together in the same relationship within an enclosure, in addition to simulating the manner in which they will be used.
(d) Materials considered. The test may be used for evaluating wall, ceiling and flooring finish materials and assemblies, including panels, tiles, boards, sprayed or brushed coatings, etc.
FIRE AND SMOKE MEASUREMENTS AND PHOTOGRAPHIC RECORD
Sec. 12-8-102.
(a) Significance. This fire test is applicable to a description of certain fire performance characteristics in appraising wall, ceiling and flooring materials, products or systems under specified fire exposure conditions in an enclosure. The test indicates the maximum extent of fire growth in an enclosure, the rate of heat release, and if they occur, the time to flashover and the time to flame extension beyond the doorway following flashover. Time to flashover is either the time when the radiant flux onto the floor reaches 20 kW/m [2] or the average temperature of the upper air reaches 1100°F (593°C). A crumpled up single sheet of newspaper may be placed on the floor 3 feet (914 mm) out from the center of the front wall.
The spontaneous ignition of this newspaper will provide a visual indication of flashover. It determines both the extent to which the wall and ceiling materials or assemblies may contribute to fire growth in a compartment and the potential for fire spread beyond the compartment under the particular conditions simulated. It does not measure the contribution of the furnishing materials.
(b) Fire measurements. The potential for the spread of fire to other objects in the enclosure interior, remote from the ignition source, is evaluated by measurements of:
The total heat flux incident at the center of the floor.
A characteristic upper level gas temperature in the test compartment.
(c) Fire spread potential. The potential for the spread of fire to objects outside the compartment of origin is evaluated by the measurement of the total rate of heat release of the fire.
(d) Smoke measurements. Measurements of the rate of production of carbon monoxide and visible smoke are taken.
(e) Photographic record. The overall performance of the test specimen is to be visually documented by full color photographic records. Videotaping of the complete fire test may be done as an alternate to the continuous photographic record. Such records may show when each area of the test specimen becomes involved in the fire.
CRSC § 0.21 Medium relevance — show source text
Notes:
Capacitance-type transducers have been found to be the most stable for this application.
The bidirectional probe is specified rather than the pilot-static tube in order to avoid problems of clogging with soot.
Duct oxygen concentration specification. A stainless steel gas sampling tube shall be located 13 feet (3962 mm) downstream from the entrance to the duct, to obtain a continuously flowing sample for determining the oxygen concentration of the exhaust gas as a function of time. A suitable filter and cold trap shall be placed in the line to remove particulates and water. The oxygen analyzer shall be of the paramagnetic or polarographic type and shall be capable of measuring the reduction in oxygen concentration over the range of 0.21 down to 0.15 with an accuracy of ± 2 percent in this concentration range. The signal from the oxygen analyzer must be within 5 percent of its final value in 30 seconds after introducing a step change in composition of the gas stream flowing past the inlet to the sampling tube.
Duct carbon dioxide concentration specification. The gas sampling tube defined in Section 12-8-112, Item 5, or an alternate tube in the same location, shall provide a continuous sample for the measurement of the carbon dioxide concentration with an analyzer which has a range of 0 to 20 percent and a maximum error of 2 percent of full-scale. The total system response time between the sampling inlet and the meter shall be no greater than 30 seconds.
Duct carbon monoxide concentration specification. The gas sampling tube defined in Section 12-8-112, Item 5, or an alternate tube in the same location, shall provide a continuous sample for the measurement of the carbon monoxide concentration with an analyzer which has a range of 0 to 10 percent and a maximum error of 2 percent of full-scale.
Optical density of smoke in duct specification (supplementary measurement). A meter shall be installed to measure the optical density of the exhaust gases in a vertical path across the width of a horizontal duct, 1 foot (105 mm) downstream of the duct velocity probe. A horizontal path should be used with a vertical duct. A suitable design for the meter is as follows: Use as a light source a number 1810 lamp which is rated at 6.3 volts, 0.40 amps, and 1.5 candela and is operated at 5 volts d.c. The lamp is mounted at the focal point of a + 20 diopter and 50 mm diameter double convex collimating lens. At the other side of the duct the collimated beam is intercepted by a + 10 diopter 50 mm diameter plane convex lens and concentrated onto the cathode of a 1P39 phototube. A Corning CS3-132 type 3304 filter (available from the Swift Glass Company, Box 890, Elmira Heights, NY 14903) is used in front of the phototube to correct its spectral response to the standard photopic curve of the human eye. The lens, filter and phototube are mounted inside of a light-tight housing which is blackened inside to minimize internal reflections. The phototube is connected to a linear operational power amplifier with an adjustable gain of 10 [6] which in turn is connected to a commercially available log ratio amplifier to produce an output voltage proportional to the optical density.
CRSC § 4.420 Medium relevance — show source text
410|≥4.420|NA|AHRI
550/590| |Water
source
electri-
cally
operated
positive
displace-
ment|<75|≤0.7885
FL
≤0.6316
IPLV.IP|≤0.7875
FL
≤0.5145
IPLV.IP|75/655|NA|NA|NA|≥3.550|NA|NA|NA|6.150|6.150| |Water
source
electri-
cally
operated
positive
displace-
ment|≥75
and
<150|≤0.7579
FL
≤0.5895
IPLV.IP|≤0.7140
FL
≤0.4620
IPLV.IP|54/445|≥4.640|≥3.680|≥2.680|NA|≥8.330|≥6.410|≥4.420|NA|NA| |Water
source
electri-
cally
operated
positive
displace-
ment|≥75
and
<150|≤0.7579
FL
≤0.5895
IPLV.IP|≤0.7140
FL
≤0.4620
IPLV.IP|75/655|NA|NA|NA|≥3.550|NA|NA|NA|6.150|6.150| |Water
source
electri-
cally
operated
positive
displace-
ment|≥150
and
<300|≤0.6947
FL
≤0.5684
IPLV.IP|≤0.7140
FL
≤0.4620
IPLV.IP|54/445|≥4.640|≥3.680|≥2.680|NA|≥8.330|≥6.410|≥4.420|NA|NA| |Water
source
electri-
cally
operated
positive
displace-
ment|≥150
and
<300|≤0.6947
FL
≤0.5684
IPLV.IP|≤0.7140
FL
≤0.4620
IPLV.IP|75/655|NA|NA|NA|≥3.550|NA|NA|NA|6.150|6.150| |Water
source
electri-
cally
operated
positive
displace-
ment|≥300
and
<600|≤0.6421
FL
≤0.5474
IPLV.IP|≤0.6563
FL
≤0.4305
IPLV.IP|54/445|≥4.930|≥3.960|≥2.970|NA|≥8.900|≥6.CRSC § 2-550 Medium relevance — show source text
″|3′-2″|4′-3″|3′-8″|3′-1″|2′-7″|2′-0″| |2-550S162-68|6′-5″|5′-10″|5′-3″|4′-9″|4′-4″|5′-5″|4′-9″|4′-3″|3′-9″|3′-4″| |2-800S162-33|—|—|—|—|—|—|—|—|—|—| |2-800S162-43|2′-6″|—|—|—|—|—|—|—|—|—| |2-800S162-54|6′-1″|5′-5″|4′-10″|4′-3″|3′-9″|4′-11″|4′-3″|3′-8″|3′-0″|2′-5″| |2-800S162-68|7′-8″|6′-11″|6′-3″|5′-9″|5′-2″|6′-5″|5′-9″|5′-1″|4′-6″|4′-0″| |2-1000S162-43|2′-10″|—|—|—|—|—|—|—|—|—| |2-1000S162-54|6′-7″|5′-10″|5′-3″|4′-9″|4′-3″|5′-4″|4′-9″|4′-1″|3′-5″|2′-9″| |2-1000S162-68|8′-8″|7′-10″|7′-2″|6′-6″|5′-11″|7′-4″|6′-6″|5′-9″|5′-1″|4′-6″| |2-1200S162-54|5′-6″|4′-10″|4′-4″|3′-11″|3′-7″|4′-5″|3′-11″|3′-6″|3′-2″|2′-11″| |2-1200S162-68|9′-7″|8′-8″|7′-11″|7′-2″|6′-6″|8′-1″|7′-2″|6′-4″|5′-8″|5′-0″| |For SI: 1 mil = 0.0254 mm, 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa, 1 pound per square inch = 6.895 kPa, 1 ksi = 1,000 psi = 6.895 MPa.
a.CRSC § 406.2.4 Medium relevance — show source text
406.2.4, 424.2, 804.2, 804.3
35-20 2025 CALIFORNIA BUILDING CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
REFERENCED STANDARDS
E662—17a: Standard Test Method for Specific Optical Density of Smoke Generated by Solid Materials
804.4.1, 804.4.2
E681—09(2015): Test Methods for Concentration Limits of Flammability of Chemical Vapors and Gases
202
E736/E736M—19: Test Method for Cohesion/Adhesion of Sprayed Fire-Resistive Materials Applied to Structural Members
704.12.3.2, 1705.15.6
E814—2013A(2017): Standard Test Method for Fire Tests of Penetration Firestop Systems
202, 714.4.1.2, 714.4.2, 714.5.1.2
E970—2017: Standard Test Method for Critical Radiant Flux of Exposed Attic Floor Insulation Using a Radiant Heat Energy Source
720.3.1
E1007—21: Standard Test Method for Field Measurement of Tapping Machine Impact Sound Transmission through Floor-Ceiling Assemblies and Associated Support Structures
1206.3
E1300—2016: Practice for Determining Load Resistance of Glass in Buildings
2404.1, 2404.2, 2404.3.1, 2404.3.2, 2404.3.3, 2404.3.4, 2404.3.5
E1354—2017: Standard Test Method for Heat and Visible Smoke Release Rates for Materials and Products Using an Oxygen Consumption Calorimeter
424.2, 602.4.1.1, 602.4.2.1, 602.4.3.1, 1402.6
E1592—2005(2017): Test Method for Structural Performance of Sheet Metal Roof and Siding Systems by Uniform Static Air Pressure Difference
1504.4.2
E1602—2003(2017): Guide for Construction of Solid Fuel Burning Masonry Heaters
2112.2
E1886—19: Standard Test Method for Performance of Exterior Windows, Curtain Walls, Doors and Impact Protective Systems Impacted by Missile(s) and Exposed to Cyclic Pressure Differentials
1609.2, 1709.5.3.1
E1966—15(2019): Standard Test Method for Fire-Resistive Joint Systems
202, 715.3.1, 1709.5.3.1
E1996—20: Specification for Performance of Exterior Windows, Curtain Walls, Doors and Impact Protective Systems Impacted by Windborne Debris in Hurricanes
1609.2, 1709.5.3.1
E2072—14: Standard Specification for Photoluminescent (Phosphorescent) Safety Markings
1025.4
E2174—20a: Standard Practice for On-site Inspection of Installed Fire Stops
1705.18.1
E2178—21a: Standard Test Method for Determining Air Leakage Rate and Calculation of Air Permeance of Building Materials
202
CMC § 2025 Medium relevance — show source text
2025 CALIFORNIA MECHANICAL CODE 505
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
APPENDIX E
CERTIFICATE OF ACCEPTANCE MECH-6A Col2 Demand Control Ventilation Systems Acceptance
(Page 2 of 3)Demand Control Ventilation Systems Acceptance
(Page 2 of 3)Project Name/Address: Project Name/Address: System Name or Identification/Tag: System Location or Area Served: Verify that systems required to employ demand controlled ventilation can vary outside ventilation flow rates based on Intent: maintaining interior carbon dioxide (CO 2 ) concentration setpoints.
Construction Inspection
- Instrumentation to perform test includes, but not limited to: a. Calibrated handheld CO 2 analyzer. b. Manufacturer’s calibration kit. c. Calibrated CO 2 /air mixtures.
- Installation. The sensor is located in the high density space between 3 feet and 6 feet above the floor or at the anticipated level of the occupants heads.
- Documentation of all carbon dioxide control sensors includes (check one of the following): a. Calibration method. Factory-calibration certificate (certificate must be attached). Field calibrated. b. Sensor accuracy. Certified by manufacturer to be no more than +/- 75 ppm calibration certificate must be attached.
A. Functional Testing. Col2 Col3 Results a.
Disable economizer controls.a.
Disable economizer controls.a.
Disable economizer controls.b.Outside air CO2~~ concentration (select one of the following).~~
Measured dynamically using CO2 sensor.
Measured dynamically using CO2 sensor.ppm ppm c.
Interior CO2 concentration setpoint (Outside CO2 concentration + 600 ppm).c.
Interior CO2 concentration setpoint (Outside CO2 concentration + 600 ppm).ppm ppm Step 1: Simulate a signal at or slightly above the CO2 setpoint or follow manufacturers recommended testing proce-
dures.Step 1: Simulate a signal at or slightly above the CO2 setpoint or follow manufacturers recommended testing proce-
dures.Step 1: Simulate a signal at or slightly above the CO2 setpoint or follow manufacturers recommended testing proce-
dures.Step 1: Simulate a signal at or slightly above the CO2 setpoint or follow manufacturers recommended testing proce-
dures.
For single zone units, outdoor air damper modulates opens to satisfy the total ventilation air called for in the certificate
of compliance.
For single zone units, outdoor air damper modulates opens to satisfy the total ventilation air called for in the certificate
of compliance.
For single zone units, outdoor air damper modulates opens to satisfy the total ventilation air called for in the certificate
of compliance.
For single zone units,
Frequently asked questions
What exactly is the “smoke density” measured here?
The standard defines smoke density as the area under the plotted curve of microammeter drop (difference from pretest) versus time; the plotted area (in square inches using the example plot scale) is the smoke density metric used for classification in § 12-71-100 .
Where must the photoelectric cell be mounted?
The photoelectric cell must be mounted a few inches below and about 12 inches (305 mm) inside the discharge end of the duct; the light source is mounted 1 inch (25 mm) above the duct directly above the cell, per § 12-71-100 .
How often do I record microammeter readings?
Record every 5 seconds for the first minute, then every 10 seconds for the next two minutes, per § 12-71-100(b)(2) .
Can I use a different meter or detector head?
The code prescribes the photoelectric cell & microammeter setup; alternate systems may be used only if they produce equivalent, documented results that reproduce the intended optical characteristics and response. The standard itself prescribes the placements and processing method in § 12-71-100 .
Where are the pass/fail thresholds?
Classification thresholds are in § 12-71-100(c): Class 1 area < 1.5 in²; Class 2 units must not develop areas more than 6.0 in² (the code text gives these numeric criteria) .
Are filters tested dirty or clean?
The standard specifies that filters are tested clean (unused) in the test method (see § 12-71-100(b)(1)) .
More in California Referenced Standards Code
- Administration and scope — CRSC Chapter 12 overview
- Air filter standards (Chapter 12‑71)
- Building and facility access / accessibility standards (Chapters 12‑11A, 12‑11B)
- Engineering regulations — quality and design of construction materials (12‑16 series)
- Exits and means of egress (Chapters 12‑10 series)
- Protective signaling systems and detectors (Chapters 12‑72‑1, ‑2, ‑3)
- Radiation shielding standards (Chapter 12‑31C)
- Referenced standards index / cross‑reference table (Part 12 listing of referenced standards)
- Releasing systems for security bars (egress-release standards)
- Standards for insulating materials (Chapter 12‑13)
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