ACOUSTICAL INFORMATION

Transcription

1 ACOUSTICAL INFORMATION Alpro has been successfully used for over 50 years to provide sound absorption for a variety of environments from gymnasiums and auditoriums to water treatment plants and outdoor amphitheaters. The key to specific sound absorption of Alpro metal ceilings, wall panels or baffle systems, given the proper perforation pattern, is to choose the correct acoustical material behind the metal. Most architects today use a glass fiber medium encapsulated, for environmental concerns, in PVC which acts as an acoustical diaphragm. Many tests have revealed that: 1. A 10% perforated area in a metal panel or greater will provide maximum sound absorption. Greater open areas will increase the acoustical transparency of the panel, but not the absorption. Standard Alpro panels are 13.2% open area. 2. In order to achieve a Noise Reduction Coefficient (NRC) of 1.0 for a wall panel you must use a 2 thick x 1.5# density acoustical element. 3. For a ceiling with a standard (14 ) test plenum you can achieve the same results with a 1-1/2 thick x 1.5# density acoustical element. 4. An increase in density of the fiberglass will increase absorption at the lower frequencies. 5. An increase in thickness over 2 x 2.0# does little to improve NRC and should be balanced in many applications as performance versus additional costs. Included in this section are: A. Summary of Alpro Acoustical Tests These tests represent applications and materials most commonly used. Alpro has other tests not published in this section. For a copy of the complete test please contact Alpro. B. Alpro Acoustics Reverberation Time Calculation Sheet Designed to help you determine sound absorption required for a specific application. Your Alpro representative will also be glad to aid you. C. Recommended Optimum Reverberation Times for Various Room Uses D. Sound Absorption Coefficients of General Building Materials and Furnishings Please use the coefficient at 500hz in making calculations. E. Glossary of Common Acoustical Terminology F. Explanation of Test Methods Associated with Alpro Products

2 Summary of ALPRO Acoustical Tests Octave Band Center Frequency, Hz Acoustical Material Mounting NCR TEST # Ceilings 1.5# 1.5" E RAL fiberglass Wall Panels 1.5# 2.0" A RAL fiberglass Wall Panels 1.5# X 2.0 RAL PVC Wrap D A-90 4" Airspace 193 Wall Panels A # X 2.0 A JM Tech Ctr fiberglass 10/23/2001 Wall Panels A # X 2.0 A JM Tech Ctr PVC Wrap 10/23/2001 Wall Panels A # X 2.0 FG D JM Tech Ctr 4" Airspace 10/23/2001 Wall Panels 2.0# X 2.0 FG A PVC Wrap D JM Tech Ctr 4" Airspace 10/23/2001 NOTES TO ABOVE TESTS: 1. All ALPRO Acoustical System metals tested were produced from.032 Pattern C Aluminum, standard 13% open perforated area. 2. Mounting: (a) E-400 Ceiling Mount is 14 depth; (b) A Mounting is directly against structural wall with no air space; (c) D-100 (100mm) utilizes a 4 air space behind fiberglass. 3. All tests for Sound Absorption are in accordance with ASTM C a. Actual installed values may vary depending upon many variables, such as type of construction and humidity. AD

3 ALPRO ACOUSTICS REVERBERATION TIME CALCULATION SHEET Job: Date: Type of Room (Gymnasium, Auditorium, Pool, Deck, etc.) Room Dimensions: L W H Room Volume: V = L x W x H = cu. ft. Absorption Area Total Material Coefficient Sq Ft Absorption Ceiling ` Floor Walls Other Total Existing Absorption: A = sabins Estimated Existing Reverberation Time: T =.05 x V = = seconds A Desired Reverberation Time: DT = seconds Absorption Required: AR =.05 x V DT = = sabins Estimated Additional Unit of Absorption Needed (AU) - Absp. Req. (AR) - Exist Absp. (A) AU = AR - A = = sabins Estimated Alpro Panels or Baffles required for additional absorption needed CAUTION: Actual field results may vary from estimated and calculated values. Calculations are based on recognized acoustical principles. Contact an acoustical consultant for additional information.

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5 Sound Absorption Coefficients of General Building Materials and Furnishings Complete tables of coefficients of the various materials that normally constitute the interior finish of rooms may be found in various books on architectural acoustics. The following short list of materials gives approximate values which will be useful in making simple calculations of the reverberation in rooms. Coefficients Materials 125 Hz 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz Brick, unglazed Brick, unglazed, painted Carpet 1/8" Pile Height /4" Pile Height /16" combined Pile & Foam /16" combined Pile & Foam Concrete Block, painted Fabrics Light velour, 10 oz. per sq. yd., hung straight in contact with wall Medium velour, 14 oz. per sq. yd., draped to half area Heavy velour, 18 oz. per sq. yd., draped to half area Floors Concrete or Terrazzo Linoleum, asphalt, rubber or cork tile on concrete Wood Wood parquet in asphalt on concrete Glass 1/4" sealed, large panes oz., operable window (in closed condition) Gypsum board, 1/2" nailed to 2x4's 16"o.c. painted Marble or Glazed Tile Plaster, gypsum or lime, rough finish or lath Same, with smooth finish Hardwood plywood paneling 1/4" thick, Wood Frame Water Surface, as in swimming pool Wood Roof Decking, tongue-and-groove cedar Air, Sabins per 1,000 cubic 50% RH

6 Absorption of Seats and Audience* Values given are in sabins per person or unit of seating at the indicated frequency 125 Hz 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz Audience, seated depending on spacing and upholstery of seats Seats, heavily upholstered with fabric Seats, heavily upholstered with leather, plastic, etc. Seats, wood veneer, no upholstery Wood pews, no cushions, per 18" length 0.4 Wood pews, cushions, per 18" length *Reference to Acoustical Manufacturers catalogs for acoustical materials data. AD

7 GLOSSARY OF TERMS Acoustic Impedance A measure of the difficulty of generating flow; it is the ratio or the sound pressure to the volume velocity due to a sound wave. Theoretically, the acoustical properties of a fibrous blanket can be defined in terms of acoustic impedance measured using an impedance tube (see Impedance Tube below). Air Flow Resistance Air Flow Resistance is a ratio of the pressure differential across a sample of the porous material to the air velocity through it. This is the most important physical property affecting sound absorption performance of a porous fibrous material, and this resistance is directly related to material properties such as density, fiber diameter and thickness. Articulation Class (AC) The Articulation Class metric measures how effectively ceilings, wall panels, and furniture systems provide speech privacy in open offices. It is a laboratory test (ASTM E 1111 for ceilings, ASTM E 1376 for wall finishes and furniture panel surfaces, and ASTM E 1375 for furniture barriers). The higher the rating, the better the privacy of the space. Articulation Index (AI) A numerically calculated measure of the intelligibility of transmitted or processed speech in open office environments. It takes into account the limitations of the transmission path and the background noise. The articulation index can range in magnitude between 0 and 1.0. If the AI is less than 0.1, speech intelligibility is generally low. If it is above 0.6, speech intelligibility is generally high. Decibel (db) Measurement of the loudness or sound pressure level. 0 db = atmosphere = threshold of excellent hearing; 120 db = atmosphere = threshold of pain. Changes of 3 to 4 db are just noticeable. Frequency The number of cycles per second measured in Hertz. Hertz (Hz) Measurement of frequency of a sound. Impact Insulation Class (IIC) Single-number rating used to compare and evaluate the performance of floor-ceiling constructions in isolating impact noise. The higher the IIC rating, the greater the isolation of impact sounds between two rooms. Impedance Tube The classical impedance tube technique is the basis for accurate measurements of surface impedance. Samples are placed at one end of a long tube and pure tone sound generated by a driver at the other end. The resultant interference between incident and reflected sound waves depends on the reflection properties and, hence, on the surface impedance of the sample. Theoretically, the acoustical properties of a fibrous material can be defined in terms of acoustic impedance. Acoustic pressure is related to the air velocity at the surface of the insulation and can be directly measured using impedance tube (ASTM E 1050). Isolated Reverberation Room In accordance with ASTM C 423, this room has massive sidewalls, floor and ceiling. The room is equipped with stationary diffusing

8 panels and may also include rotating diffusing panels to further improve sound diffusion. In the C 423 test method, the rate of decay of the room sound pressure level is measured at several positions. From the measured decay rate, the specimen sound absorption is calculated which is then used to obtain the single number NRC rating. Noise Criteria (NC) Used to set acceptable noise levels for various interior uses, NC involves different frequency bands. The lower the rating, the quieter the room needs to be. Concert halls and broadcast studios require an NC rating of less than 20. Kitchens, laundries, and computer rooms are 45 to 50. Noise Reduction Coefficient (NRC) A measure of the acoustical absorption performance of a material. This single number rating is calculated by averaging the sound absorption coefficients measured at 250, 500, 1000, and 2500 Hz. Sabin A unit of acoustic absorption equivalent to the absorption by one square foot of a perfect absorber. Sones Linear measurement of loudness correlating with subjective impressions. One sane is the loudness of a sound whose level is 40 phons. Sound Absorption Coefficient The effectiveness of a material to absorb sound is defined in terms of its sound absorption coefficient (ratio of incident sound energy to absorbed sound energy). The sound absorption coefficient is a function of how the specimen is mounted. For ASTM C 423 tests, ASTM E 795 provides a classification Type A specimen placed directly on the reverberation room surface. For E405, the specimen is placed 405 mm above the reverberation room surface. Sound Transmission Class (STC) The preferred single figure rating system designed to give an estimate of the sound insulation properties of a partition or a rank ordering of a series of partitions. It is intended for use primarily when speech and office noise constitute the principal noise problem. The sound insulation performance of floors and walls are often expressed by their STC number. STC is a single number rating computed using ASTM E 413 from measured third octave transmission loss data obtained in accordance with ASTM E 90. STC 25, normal speech may be audible. STC 50, loud speech is likely to be inaudible. Speech Interference Level (SIL) A calculated quantity providing a guide to the interfering effect of a noise on reception of speech communication. An average dba rating for frequencies of 500, 1000, 2000, and 4000 cycles. Transmission Loss (TL) The transmission loss of a separating element (floor, wall, or other item) is simply the ratio of the incident sound power to the transmitted sound power expressed in decibels. ASTM E 90 defines the method for conducting this test in the laboratory. Data is reported for third octave frequency bands over the range 125 to 4000 Hz. AD

9 Explanation of Test Methods The following are brief descriptions of the test methods used to determine data published. For complete details of ASTM test methods and complete test titles, write American Society for Testing and Materials, 100 Barr Harbor West, Conshohocken, PA AMA-1-11 and ASTM E 1414 Ceiling Sound Attenuation These tests provide a measure of the ability of an acoustical ceiling material to attenuate (weaken) the intensity of sound energy passing from one room to another via the pathway formed by a plenum space shared by two adjacent rooms. Sound energy covering the frequency range of Hz is generated in one of the test rooms and the resulting difference in sound pressure levels between the two rooms at 16 standardized center frequencies is measured. The resulting values are known as sound attenuation factors. This data is used to calculate the Ceiling Attenuation Class (CAC) in accordance with ASTM E 413. ASTM C 423 Reverberant Room Sound Absorption This test measures the ratio of sound energy absorbed by a surface to the energy striking the surface from all angles. This numerical measure of the ability to absorb sound is known as an absorption coefficient. Coefficients can take on any numerical value from 0 to 1.0. Coefficients are generally presented for six standardized test frequencies over the range of Hz. The single figure rating for a material is the average of four coefficients from Hz inclusive. This is the Noise Reduction Coefficient (NRC). The NRC is expressed to the nearest multiple of.05. It should be noted that a difference in NRC of less than.10 is seldom detectable in a completed installation. ASTM E 119 (UL 263) Fire Resistance This testing method measures a construction product s ability to prevent the spread of fire from one building compartment to another while retaining the structural strength properties of the assembly. Fire resistance classifications are given in terms of the length of test time elapsing before one or more limiting criteria are reached. It is important to remember that classifications are established for entire system designs and not for individual components within the design. ASTM E 84 (UL 723) Surface Burning Characteristics This test procedure is often referred to as the tunnel test method. The purpose of this test is to determine, under controlled laboratory conditions, the comparative surface burning characteristics of the material under test. The flame spread and smoke developed values which are determined by this test method are expressed as single number designations comparing the test sample performance with that of red oak which is 100 and inorganic reinforced cement board which is taken as 0.

10 Observations of flame spread distance and time are recorded. The smoke density at the outlet end of the tunnel is recorded during the test period and is used to calculate the smoke developed values. Fire data provided is determined under controlled laboratory conditions using the ASTM E 84 or UL 723 standard and may not be predictive of the materials performance in actual use. ASTM E 1477 Light Reflectance This test method describes the evaluation of light reflectance and acoustical material where the application is primarily for designing the level of room illumination. ASTM C 635 and ASTM C 636 Composition and Installation of Metal Ceiling Suspension Systems for Acoustical Tile and Lay-In Panels These two ASTM specifications cover the structural properties of metal ceiling suspension systems and the proper installation techniques for these systems. AD

11 5/8" 4" AO - / STEEL MAXIMUM LENGTH: 120" 5/8" 4" AI - / STEEL MAXIMUM LENGTH: 120" DIMENSIONS 40 3/4" 41 1/2" 51 1/4" 52" NOTE: ALL DIMENSIONS BASED ON.032" STUCCO EMBOSSED PERFORATED PANELS. DIMENSIONS ARE AND WILL VARY WITH DIFFERENT THICKNESSES AND TYPES OF MATERIAL. STANDARD FACTORY TOLERANCES: LENGTH: ± 5/32" WIDTH: ± 3/16" DIAGONAL: ± 3/16" AVAILABLE MATERIAL STEEL.032" 24 GAUGE 26 GAUGE PATTERN "A" PANELS

12 1/2" 2 1/2" / STEEL MAXIMUM LENGTH: 120" DIMENSIONS 42 3/4" 44 3/4" 1/2" 2 1/2" / STEEL MAXIMUM LENGTH: 120" DIMENSIONS 54 3/4" 55 3/4" NOTE: ALL DIMENSIONS BASED ON.032" STUCCO EMBOSSED PERFORATED PANELS. DIMENSIONS ARE AND WILL VARY WITH DIFFERENT THICKNESSES AND TYPES OF MATERIAL. STANDARD FACTORY TOLERANCES: LENGTH: ± 5/32" WIDTH: ± 3/16" DIAGONAL: ± 3/16" AVAILABLE MATERIAL STEEL.032" 22 GAUGE 24 GAUGE 26 GAUGE PATTERN "B" PANELS

13 5/8" 2 23/32" MAXIMUM LENGTH: 144" DIMENSIONS 40 3/8" 42" 51 5/8" 52 3/4" 22GA & 24GA STEEL MAXIMUM LENGTH: 144" DIMENSIONS 26GA STEEL MAXIMUM LENGTH: 144" DIMENSIONS 40 7/8" 42 1/2" 40 7/8" 42 1/2" 51 5/8" 52 3/4" NOTE: ALL DIMENSIONS BASED ON.032" STUCCO EMBOSSED PERFORATED PANELS. DIMENSIONS ARE AND WILL VARY WITH DIFFERENT THICKNESSES AND TYPES OF MATERIAL. STANDARD FACTORY TOLERANCES: LENGTH: ± 5/32" WIDTH: ± 3/16" DIAGONAL: ± 3/16" AVAILABLE MATERIAL STEEL.032" 22 GAUGE 24 GAUGE 26 GAUGE PATTERN "C" PANELS

14 5 15/16" 1 19/32" / STEEL MAXIMUM LENGTH: 120" DIMENSIONS 38 5/8" 39 1/2" 5 15/16" 1 19/32" / STEEL MAXIMUM LENGTH: 120" DIMENSIONS 47 1/2" 49 1/2" NOTE: ALL DIMENSIONS BASED ON.032" STUCCO EMBOSSED PERFORATED PANELS. DIMENSIONS ARE AND WILL VARY WITH DIFFERENT THICKNESSES AND TYPES OF MATERIAL. STANDARD FACTORY TOLERANCES: LENGTH: ± 5/32" WIDTH: ± 3/16" DIAGONAL: ± 3/16" AVAILABLE MATERIAL STEEL.032" 22 GAUGE 24 GAUGE 26 GAUGE PATTERN "D" PANELS

15 1/2" 4 1/8" EO 1/2" 4 1/8" EI MAXIMUM LENGTH: 120" DIMENSIONS STEEL MAXIMUM LENGTH: 120" DIMENSIONS 53 3/4" 54 3/4" 54" 55" NOTE: ALL DIMENSIONS BASED ON.032" STUCCO EMBOSSED PERFORATED PANELS. DIMENSIONS ARE AND WILL VARY WITH DIFFERENT THICKNESSES AND TYPES OF MATERIAL. STANDARD FACTORY TOLERANCES: LENGTH: ± 5/32" WIDTH: ± 3/16" DIAGONAL: ± 3/16" AVAILABLE MATERIAL STEEL.032" 24 GAUGE 26 GAUGE PATTERN "E" PANELS

16 1 1/2" 3/8" / STEEL MAXIMUM LENGTH: 144" DIMENSIONS 39" 39 1/4" 49 7/8" 50" AVAILABLE MATERIAL STEEL.032" 24 GAUGE 26 GAUGE NOTE: ALL DIMENSIONS BASED ON.032" STUCCO EMBOSSED PERFORATED PANELS. DIMENSIONS ARE AND WILL VARY WITH DIFFERENT THICKNESSES AND TYPES OF MATERIAL. STANDARD FACTORY TOLERANCES: LENGTH: ± 5/32" WIDTH: ± 3/16" DIAGONAL: ± 3/16" PATTERN "F" PANELS

17 3/32" 5/16" TYP 60" MAX WIDTH / STEEL MAXIMUM SIZE: 60" x 24" RECOMMENDED FOR LAY-IN OR TRIMMED APPLICATIONS ONLY. STANDARD LAY-IN SIZES ARE 23 3/4" x 23 3/4" AND 47 3/4" x 23 3/4". AVAILABLE MATERIAL STEEL.032" 24 GAUGE.020" 26 GAUGE NOTE: ALL DIMENSIONS BASED ON.032" STUCCO EMBOSSED PERFORATED PANELS. DIMENSIONS ARE AND WILL VARY WITH DIFFERENT THICKNESSES AND TYPES OF MATERIAL. STANDARD FACTORY TOLERANCES: LENGTH: ± 5/32" WIDTH: ± 3/16" DIAGONAL: ± 3/16" PATTERN "H" PANELS

18 3/8" 1 1/4" / STEEL MAXIMUM LENGTH: 144" DIMENSIONS 40 1/2" 41 5/8" 51" 52" AVAILABLE MATERIAL STEEL.032" 22 GAUGE 24 GAUGE 26 GAUGE NOTE: ALL DIMENSIONS BASED ON.032" STUCCO EMBOSSED PERFORATED PANELS. DIMENSIONS ARE AND WILL VARY WITH DIFFERENT THICKNESSES AND TYPES OF MATERIAL. STANDARD FACTORY TOLERANCES: LENGTH: ± 5/32" WIDTH: ± 3/16" DIAGONAL: ± 3/16" PATTERN "J" PANELS

19 7/16" WIDTH / STEEL MAXIMUM LENGTH: 120" DIMENSIONS WIDTH 4" MIN 4 11/16" MIN 5 11/16" MIN 12" MAX 12 11/16" MAX 13 11/16" MAX AVAILABLE MATERIAL STEEL.032" 22 GAUGE 24 GAUGE 26 GAUGE NOTE: ALL DIMENSIONS BASED ON.032" STUCCO EMBOSSED PERFORATED PANELS. DIMENSIONS ARE AND WILL VARY WITH DIFFERENT THICKNESSES AND TYPES OF MATERIAL. STANDARD FACTORY TOLERANCES: LENGTH: ± 5/32" WIDTH: ± 3/16" DIAGONAL: ± 3/16" 3/4" ENLARGED REVEAL DETAIL "MARK-7" PANELS

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28 24" OR 48" ON CENTER 23 3/4" OR 47 3/4" 4" 5/8" AO-GRID PANEL / STEEL 24" OR 48" ON CENTER 23 3/4" OR 47 3/4" 4" 5/8" AI-GRID PANEL / STEEL AVAILABLE MATERIAL STEEL.032" 24 GAUGE 26 GAUGE NOTE: ALL DIMENSIONS SHOWN ARE. STANDARD FACTORY TOLERANCES: LENGTH: ±1/16" WIDTH: +1/16" -1/8" DIAGONAL: ± 1/8" PATTERN "A" GRID PANELS

29 24" OR 48" ON CENTER 23 3/4" OR 47 3/4" 1/2" 2 1/2" B-GRID PANEL / STEEL AVAILABLE MATERIAL STEEL.032" 22 GAUGE 24 GAUGE 26 GAUGE NOTE: ALL DIMENSIONS SHOWN ARE. STANDARD FACTORY TOLERANCES: LENGTH: ±1/16" WIDTH: +1/16" -1/8" DIAGONAL: ± 1/8" PATTERN "B" GRID PANEL

30 24" OR 48" ON CENTER 23 3/4" OR 47 3/4" 5/8" 2 23/32" C-GRID PANEL / STEEL AVAILABLE MATERIAL STEEL.032" 22 GAUGE 24 GAUGE 26 GAUGE NOTE: ALL DIMENSIONS SHOWN ARE. STANDARD FACTORY TOLERANCES: LENGTH: ±1/16" WIDTH: +1/16" -1/8" DIAGONAL: ± 1/8" PATTERN "C" GRID PANEL

31 24" OR 48" ON CENTER 23 3/4" OR 47 3/4" 4 1/8" 1/2" EO-GRID PANEL / STEEL 24" OR 48" ON CENTER 23 3/4" OR 47 3/4" 4 1/8" 1/2" EI-GRID PANEL / STEEL AVAILABLE MATERIAL STEEL.032" 24 GAUGE 26 GAUGE NOTE: ALL DIMENSIONS SHOWN ARE. STANDARD FACTORY TOLERANCES: LENGTH: ±1/16" WIDTH: +1/16" -1/8" DIAGONAL: ± 1/8" PATTERN "E" GRID PANELS

32 24" OR 48" ON CENTER 23 3/4" OR 47 3/4" 3/8" 1 1/2" F-GRID PANEL / STEEL AVAILABLE MATERIAL STEEL.032" 24 GAUGE 26 GAUGE NOTE: ALL DIMENSIONS SHOWN ARE. STANDARD FACTORY TOLERANCES: LENGTH: ±1/16" WIDTH: +1/16" -1/8" DIAGONAL: ± 1/8" PATTERN "F" GRID PANEL

33 24" OR 48" ON CENTER 23 3/4" OR 47 3/4" 3/32" 5/16" H-GRID PANEL / STEEL STANDARD DIMENSIONS MODULE SIZE PANEL SIZE 24" x 24" 23 3/4" x 23 3/4" 24" x 48" 23 3/4" x 47 3/4" AVAILABLE MATERIAL STEEL.032" 24 GAUGE.020" 26 GAUGE NOTE: ALL DIMENSIONS SHOWN ARE. STANDARD FACTORY TOLERANCES: LENGTH: ± 1/16" WIDTH: +1/16" -1/8" DIAGONAL: ± 1/8" PATTERN "H" GRID PANEL

34 24" OR 48" ON CENTER 23 3/4" OR 47 3/4" 3/8" 1 1/4" NOMNAL J-GRID PANEL / STEEL AVAILABLE MATERIAL STEEL.032" 22 GAUGE 24 GAUGE 26 GAUGE NOTE: ALL DIMENSIONS SHOWN ARE. STANDARD FACTORY TOLERANCES: LENGTH: ±1/16" WIDTH: +1/16" -1/8" DIAGONAL: ± 1/8" PATTERN "J" GRID PANEL