Some standard content:
Industry Standards of the People's Republic of China
Technical Conditions for Mufflers for Fans
1 Subject Content and Scope of Application
JB/T6891—93
This standard specifies the mufflers for fans (below (referred to as muffler) technical requirements, performance test methods, inspection rules and marking, packaging, storage, transportation and other requirements.
This standard applies to various air inlet, air outlet, and vent mufflers used in centrifugal and axial flow fans, blowers, and compressors. The conveying medium is air or other weakly corrosive gases, and the temperature does not exceed 150C. The pressure does not exceed 0.1MPa, and the dust density does not exceed 150mg/m3. Referenced standards
GB1084
Tolerances and fits, regulations without tolerances
Shape and position tolerances, without tolerances Specifies GB 1184
GB13306
product labeling
GB3102.7
GB3235
GB3947
GB4760
and units
Basic ventilator types, dimensions, parameters and performance curves Acoustic terminology
Muffler measurement method
ZB J72 038
ZB J72 039
JB4361 | | tt | | JB4364 | | tt |
General technical conditions for fan packaging
JB/T6444
JB/T6885
Ventictor round flange size
JB/T6886 fan painting Technical Conditions
3 Terminology
3.1 The terms, quantities, and unit names and symbols used in this standard are in compliance with the provisions of GB3947, GB3102.7, JB4361 and other relevant standards.
3.2 Anechoic index
Under the calibrated air flow velocity condition, the anechoic value of unit length and unit cross-sectional area, its mathematical expression is: ALAO
=(S/ S).(L/d,)
Where: n——--silence index;
ALAo-. When the airflow speed is Vu, the lowest dynamic A sound level silencing value, dB +S, - the total cross-sectional area of ??the muffler, m\; S2 - the cross-sectional area of ??the air flow channel of the muffler, m; L - the effective length of the muffler, m;
Ministry of Machinery Industry of the People's Republic of China 1993-07 -13 Approved for implementation on 1994-07-01
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JB/T 6891—93
d2 - the equivalent diameter of a single airflow channel area, m. 3.3 Orifice plate peripheral distance
The minimum distance between the edge of the orifice plate and the edge of the outermost perforation. 4Technical requirements
Other requirements not specified in this standard may be stipulated in the agreement between the supplier and the buyer. 4.1 Basic design requirements
4.1.1 Mufflers should comply with the requirements of this standard and be designed and manufactured in accordance with the drawings, technical documents approved by the prescribed procedures, and the technical agreement or contract signed by both the supplier and the buyer.
4.1.2 The service life of the muffler under the conditions that meet the use requirements is; resistive or impedance composite mufflers are not less than 5a; there are many micro-hole plates, small hole injection, throttling and pressure reduction and resistance mufflers Yu 8a; The safe and normal operation time of various types of mufflers before the first overhaul is not less than 4000h. 4.1.3 The design of the muffler should have a reasonable structure, sufficient stiffness and strength, meet the performance requirements, be small in size, light in weight, simple in process, and economical.
The silencer series products should use the silencer index as a comprehensive design index for assessment: low-pressure fans are equipped with inlet and outlet silencers, and the silencer index should not be less than 1.5; medium and high-pressure fans, blowers, compressors, and Roots blowers are equipped For all types of mufflers, the silencing index should be no less than 2. 4.2 Performance requirements
4.2.1 Acoustic performance requirements
4.2.1.1 Muffler silencer frequency band width
Resistive or anti-composite type The muffler should be no less than 4 octaves; the resistance, resonance type, small hole injection muffler should be no less than 2 octaves corresponding to the fundamental frequency and its low-order (or first) harmonics, and other types of mufflers should not be Less than 3 octaves. 4.2.1.2 The sound attenuation value of the muffler should generally be expressed in terms of A-weighted insertion loss. A reasonable sound attenuation value can be determined based on different noise reduction requirements and relevant national environmental protection and health standards. 4.2.1.3 For series mufflers, in order to facilitate user selection and product verification, the static or dynamic octave band insertion loss of the muffler as a whole or per unit muffler length should be given in the product manual. The insertion loss in the above items should be given. It is allowed to replace it with the corresponding sound transmission loss. 4.2.2 Aerodynamic performance requirements
4.2.2.1 Under normal circumstances, the aerodynamic performance of the muffler is expressed by the total pressure loss coefficient of the muffler "s". For resistive mufflers, the value per unit length (1m) is not greater than 0.8; for micro-orifice plate mufflers, The value per unit length (1m) shall not be greater than 0.2; the value of the complete unit of resistance, small hole injection, resonance type, and impedance composite mufflers shall not be greater than 1.4. For other types of mufflers, the value per unit length (1m) shall not be greater than 0.5. 4.2. 2.2 When there are requirements for pressure loss, the maximum total pressure loss of the muffler should be controlled. The total pressure loss of the muffler used for low-pressure fans in air-conditioning systems, textile ventilators and other ventilation systems should be less than 10% of the full pressure of the fan. When it is not greater than 300Pa, the total pressure loss of the silencer is allowed to exceed 10%: but the maximum value should not be greater than 49Pa. The total pressure loss of the silencer used for power station boiler air supply, mine tunnel air supply, cooling air supply, sintering fan and other fans should be less than The total pressure of the fan should be 5%, and its maximum value should not exceed 490Pa. For blast furnace air supply, material transportation, etc., the total pressure loss of the muffler for medium and high-pressure fans should be less than 3% of the fan's total pressure, and its maximum value should not exceed 800Pa.
The total pressure loss is generally not considered for venting mufflers. 240
(A) Above. For series mufflers, the airflow regeneration noise values ??or calculation formulas at different flow rates should be given in the product manual. 4.2.4 Under the conditions of guaranteed performance, the flow rate range of the muffler is generally 90% of the rated flow. to 110%. 4.2.5 Under guaranteed performance conditions, the maximum passing medium pressure is 120% of the rated pressure; the maximum passing medium temperature is the rated temperature plus 50°C
4.3 Material requirements||tt. ||4.3.1 All materials used in the muffler must comply with the brand, specification, variety, and material properties stipulated in national or industry standards and should meet the safety and life requirements of the muffler
Material substitution procedures must be handled in accordance with the prescribed procedures. And be signed and approved by the product designer or technical supervisor. 4.3.2 Various sound-absorbing materials used in the muffler should be identified by a nationally recognized acoustic laboratory, with detailed sound absorption coefficients and spectral characteristics, complete data, good process performance, and high quality. Stable, non-polluting, technologically mature product. The allowable capacity error of layered fiber sound-absorbing materials is ±5%: the bulk sound-absorbing materials must have stable physical and chemical properties and are not allowed to form corrosion or other fibrous absorbers. The allowable moisture content of acoustic materials is no more than 5%, and the impurity content is no more than 3%. 4.3.3 The perforated board should be made of metal or non-metallic materials with stable physical and chemical properties. The perforated board used as a protective panel has an average penetration rate. It should be no less than 20%, and the perforation rate error is ±2%; the flatness of metal material orifice plates shall be carried out according to GB1184 unspecified tolerance level D precision, and the flatness of non-metal orifice plates shall not exceed 5/1000mm; the edges of perforated plates shall be smooth and have no sharp corners. Burrs, orifice plate surface is clean, no dirt or rust marks. The minimum peripheral distance of the orifice plate is not less than 5mm.
4.3.4 When fiber-type fabric is used as a protective material, its thickness should not be greater than 0.15mm. Generally, plain weave, alkali-free, stable physical and chemical properties, and anti-aging fabric should be used.
4.3.5 The muffler sealing material should be rubber products or other materials with stable physical and chemical properties, resistance to aging impact, no corrosion and no pollution.
4.3.6 All standard parts, purchased parts, and outsourced parts should have product inspection certificates or product qualification certificates. 4.4 Processing technical requirements
4.4.1 The processing technical requirements for riveted welding parts are as follows: 4.4.1.1 The riveted and welded parts of the muffler include shells, cores, mufflers (pieces), muffler baffles, rectifiers, Transition pipes, connecting flanges and other metal or non-metal parts.
4.4.1.2. If the drawing of the riveted weldment does not indicate the linear limit deviation of the tolerance dimension, it shall be implemented according to ZBJ72039 Table 7B level accuracy. 4.4.1.3 If the drawing of the riveted weldment does not indicate the tolerance level of the shape and position tolerance, it shall be carried out according to ZBJ72039 Table 8F level precision. 4.4.1.4 All welds of the silencer (including welding and brazing) shall comply with relevant national standards. Welds are not allowed to have defects such as pores, slag, weak welds, burn-through, and flesh bite. It is not allowed to burn the sound-absorbing material during welding, and welding slag and spatter are not allowed to block the perforations of the cold orifice plate. The welding quality should comply with the relevant regulations of ZBJ72038.
4.4.1.5 When using blind rivets for connection, attention should be paid to the smooth fit of the rivet joints on both sides without any deflection. The rivet hole diameter is not allowed to be more than 0.5mm larger than the rivet diameter, and the total riveting thickness should be less than or equal to the allowable connection thickness of the rivet. 4.4.2 If the mechanical cutting drawing of the muffler does not indicate the limit deviation of the tolerance size, it shall be implemented in accordance with GB1804. The tolerance level is IT14, and the length is half of IT (i.e. Js or js). The drawings do not indicate the tolerance level of shape and position tolerances, and they shall be carried out according to the D-level accuracy specified in GB1184. It is recommended to give priority to the first series of values ??for surface roughness, and the allowable value of R is 12.5 μm. 4.4.3 The filling capacity and filling method of sound-absorbing materials must comply with the drawing requirements. Filled with bulk sound-absorbing materials, the capacity error of a single muffler (piece) is ±3%.
4.4.4 Technical requirements for assembly and installation
4.4.4.1 The muffler and the main engine or pipe are generally connected by flanges. The flange connection surface must be equipped with elastic bearings. The flange surface is flat, sealed, and free of warping and misalignment. Flange connection dimensions should generally comply with the requirements of JB/T6885. In order to reduce the impact of chassis vibration on the noise reduction performance, 241
should use soft connections as much as possible.
JB/T 6891—93
4.4.4.2 The silencer (sheet) is allowed to be installed directly in cement or other metal channels. The channel wall is required to be smooth and flat, without air flow obstructions or sudden cross-sections, and the silencing spacing must meet the drawing requirements. The installation method of the muffler (piece) complies with the relevant construction regulations and drawings. It generally adopts a detachable structure. It is not allowed to use strong force or tools to press the assembly and disassembly to avoid deformation of the muffler (piece). 4.4.4.3 Muffler Permission Install horizontally, vertically or tilted. The dead weight of the muffler is not allowed to be directly supported on the fan or supervisory channel. 4.4.4.4 When the muffler is connected by a transition pipe, its equivalent expansion angle on one side shall not be larger than 15°, and the air flow must be ensured to pass through the muffler section evenly. The transition pipe connecting flange shall comply with the requirements of 4.4.4.1. 4.5 The painting of the muffler shall be carried out in accordance with JB/T6886. 5 Test methods
5.1 When conducting acoustic and aerodynamic performance tests on various air inlet and outlet mufflers on the test bench, they shall be implemented in accordance with JB4364. 5.2 For vented mufflers, mufflers that require on-site testing and mufflers that cannot be tested on the test bench for other reasons, the acoustic performance test shall be performed in accordance with GB4760. Generally speaking, aerodynamic performance can be regarded as equivalent if the test results obtained according to the two standards JB4364 and GB4760 are not tested. 5.3 The allowable error value of the performance test is as follows;
The octave insertion loss shall not be lower than the design value 3dB; the total pressure loss coefficient shall not be greater than the design value 0.05; the airflow regeneration noise A sound power shall not be greater than the design value 2dBA). 6 Inspection rules
6.1 Factory inspection
6.1.1 Muffler products must pass the inspection by the inspection department and be accompanied by a product certificate before they can be released." 6.1.2 Muffler series products generally do not need to undergo performance testing before leaving the factory, and their performance is subject to the type test results. If necessary, you can go to the site to test the noise reduction effect according to the conditions.
6.1.3 Material inspection shall be carried out in accordance with the requirements of Article 4.3, and records of each inspection shall be kept for future reference. 6.1.4 Welding and riveting quality inspection shall be carried out in accordance with the requirements of 4.4, 1.5 and 4.4.1.6. 6.1.5 Appearance inspection
6.1.5.1 The overall dimensions, connection dimensions, and foundation dimensions of the muffler should all meet the drawing requirements. Shells, ribs, flanges and other metal or non-metal parts must be neat, clean, free of rust marks and dirt, no cutting burrs, no pits, scratches, damage, staggered corners, missing corners and other obvious defects. 6.1.5.2 No welding slag or flux residue is allowed in all welds. Within a length of 1m, no more than 5 welding spatters with a particle size greater than 1mm are allowed; within a length of lm, the width deviation of the welding seam is not greater than 3mm; the height of the welding seam The deviation is not more than 2mm; due to welding, riveting or other reasons, the perforation rate of the blocked orifice plate is not more than 2%. 6.1.5.3 All exposed connecting parts must be as unified as possible or arranged in a regular manner. 6.1.5.4． The appearance of the muffler is smooth, beautiful, and uniform in color, and the edges of different colors are clearly spaced, eye-catching, and neat. The paint surface is not allowed to sag, blister, shrink, turn white, lose luster, and have obvious uneven thickness or peeling. 6.1.5.5 The perforated part of the protective material shall not be stained with oil, dust, paint or other impurities. 6.2 Type inspection
6.2.1 Type inspection shall be carried out in one of the following situations: trial production and identification of new products or old products transferred to factory production; a.
b. After formal production, if there are major changes in structure, materials, and processes that may affect product performance: when production is resumed 2 years after the product has been discontinued;
c.
d.
When the national quality supervision agency requests type inspection. 6.2.2 Type inspection shall include the following items: 242
8,
JB/T6891--93
performance test, which shall be carried out in accordance with the requirements of the test indicators specified in JB4364 or GB4760; According to the items specified in 6.1.3~6.1.5; b.
Processing accuracy of riveted weldments and other parts
c.
Sound-absorbing material filling quality, according to 4.4.3 Carry out inspection. dt
6.2.3 The curves and charts drawn from the type inspection performance test results can be used as a basis for preparing product instructions or product performance evaluation. bZxz.net
6.2.4 When performing unconditional performance tests on large-scale muffler products, for mass-produced series products, model-level or prototype replacement products should be used for performance tests. If a single large-scale product is manufactured using mature technology, it is allowed to be exempted. Performance testing. 7 Marking, packaging, storage, transportation
7.1 Marking
7.1.1 Each muffler should have a product nameplate nailed in a conspicuous position. 7.1.2 The product nameplate size and technical requirements should comply with the regulations of GB/T13306. 7.1.3 The main contents of the muffler product nameplate include: product name, model, rated flow, rated pressure, rated temperature, sound attenuation capacity (A-weighted insertion loss or sound transmission loss), through medium, total pressure loss coefficient or total pressure loss , product number, manufacturing date, factory name. The quantities, units and symbols used on the nameplate should comply with the relevant national legal measurement unit standards. 7.1.4 When there are directional and other special requirements, corresponding signs should be given and nailed to the appropriate location on the product. 7.2 Packaging
7.2.1 The factory packaging of muffler products shall refer to JB/T6444 Hotline, and simple packaging that is rainproof and moisture-proof is allowed. 7.2.2 When the muffler equipped with sound-absorbing materials is packaged separately, rain-proof, moisture-proof, and dust-proof measures should be taken, and it should be bundled firmly to ensure that the performance is not affected.
7.3 Storage and transportation
7.3.1 Muffler products should generally be stored indoors and are strictly prohibited from being stored in humid or corrosive gas environments. 7.3.2 Muffler products equipped with sound-absorbing materials must be covered with plastic sheeting or rainproof cloth if stored in the open air. The maximum period of open storage should not exceed six months.
7.3.3 Muffler products that have been stored for a long time should be inspected for appearance quality again before leaving the factory. If bubbling or peeling paint is found, they should be repaired in time. Important products should also undergo acoustic and aerodynamic performance testing. 7.3.4 Muffler products are allowed to be packaged as a whole or separately for transportation, and should comply with relevant transportation regulations such as waterways and railways. 8Quality Guarantee
8.1 Under normal installation and use conditions, if there is a product quality problem, such as welding falling off, sound-absorbing material blowing away, or a significant reduction in sound attenuation, the manufacturer shall be responsible for free repairs within 1 year after the product leaves the factory. or replace. 8.2 Before the muffler product leaves the factory, the product certificate, product instructions or samples must be provided to the buyer along with the product. For important products or split products, product outline drawings, installation basic drawings, packing lists and complete supply lists should also be provided. All accompanying documents should be packed in moisture-proof bags and placed in the main packaging box or main packaging box. Additional notes:
This standard is proposed and coordinated by the National Technical Committee for Fan Standardization. This standard is drafted by Wuhan Blower Guang. The main drafter of this standard: Zhou Guohua.
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