Clean room design and acceptance construction specifications

As a "controlled environment", the clean room has characteristics different from other construction projects. Although any construction project includes design, completion acceptance, daily maintenance and other links, the clean room still needs to be confirmed through debugging, testing and comprehensive evaluation. It must not be hasty and put into operation in a hurry.

The design content of the clean room includes

• Reasonable arrangement of process flow and building plan.

• Select building structure and materials that meet the characteristics of the clean room;

• Clean room design should be based on the local energy supply background at that time, and select reliable and economical cold and heat sources.

• Divide and arrange air conditioning purification and exhaust systems.

• Select reasonable air purification and ventilation equipment;

Whether it is a newly built or renovated Clean Room, it must be carried out in accordance with relevant national standards and specifications.

The appearance inspection of each project in the clean room should meet the following requirements

• The installation of various pipelines, automatic fire extinguishing devices and air purification Equipment should be correct, firm and tight.

• The connection between high, medium and primary filters and the support frame and the connection between the air duct and the equipment should be reliably sealed:

• Various adjustment devices should be tight, flexible and easy to operate;

• Various air purification equipment, static pressure boxes, ventilation systems, etc. should be cleaned to ensure dust-free;

• The inner walls, ceiling surfaces and floors of the clean room should be smooth, flat, uniform in color, dust-free, floor static electricity, etc.;

• When the supply and return air vents and various terminal devices, such pipelines, lighting and power line piping, etc. pass through the clean room, the sealing treatment at the crossing should be strict and reliable;

• Various brushing and insulation projects in the clean room should comply with relevant regulations;

Documents required for the completion acceptance of the clean room

• Design documents, design Change description documents and relevant agreements, completion drawings;

• Factory certificates or inspection documents for main materials, equipment and regulating devices, automatic control systems, etc.;

• Quality inspection and evaluation tables for various projects;

• Start-up and completion reports, closed records of hidden engineering systems and pipeline hidden engineering systems, equipment unpacking inspection records, pipeline pressure test records, pipeline system purge records, air duct leak detection records, intermediate acceptance forms and completion acceptance forms;

• Records of various equipment performance indicators in the clean room.

Comprehensive performance evaluation of clean rooms

After the completion acceptance of clean rooms, the inspection of clean rooms should generally be presided over by a third party with relevant qualifications or relevant authorizations, clean room inspection experience, and advanced and complete inspection instruments and meters. The contractor, design, construction, and supervision units should cooperate on site to complete the comprehensive performance evaluation of the clean rooms.

Summary

The design, construction, installation, and maintenance of clean rooms must be carried out in accordance with the relevant standards and specifications of the International Organization for Standardization IS0 14644, and must be dust-free, sterile, energy-saving, fire-proof, and safe.

Reference to some contents of clean workshop design specifications

1. Introduction to clean workshop

With the process of global economic integration, Chinese enterprises are not only competing fiercely with domestic enterprises, but also with foreign enterprises in a broader and more intense competition. Therefore, our current enterprises have to transform, upgrade and innovate, because only in this way can we survive. In this business environment, clean technology will be more and more valued by us, because clean workshops can not only ensure the health of workers, but also have a significant effect on the quality, precision, yield and stability of products.

2. Relevant policies and guidelines for clean workshop design

The design of clean workshops must implement the relevant policies and guidelines of the country, and must meet the requirements of advanced technology, economic rationality, safety and applicability, quality assurance, conservation and environmental protection. Clean workshop design should create necessary conditions for construction, installation, testing, maintenance management and safe operation, and should meet the relevant requirements of current national standards and specifications.

3. Air cleanliness level

The inspection of the air cleanliness level of clean workshops should be based on the number of dust particles tested under dynamic conditions. The test of air cleanliness in clean workshops shall comply with the following table:

Note: For the calculation of dust particles greater than or equal to 5 microns in clean workshops with air cleanliness of Class 100, multiple sampling should be carried out. To ensure that the test value is reliable.

4. Overall design of clean workshops

The selection of the location of clean workshops should be determined after comparison based on needs, economy, etc.:

• It should be in areas with low atmospheric dust concentration and good natural environment;

• It should be away from railways, docks, airports, traffic arteries, factories and storage warehouses that emit a large amount of dust and harmful gases, and other areas with serious air pollution, vibration or noise interference.

• It should be arranged in areas with clean environment in the factory area, where people and goods flow do not pass through or rarely pass through.

• When there is a chimney on the windward side of the maximum frequency wind direction of the clean workshop, the horizontal distance between the clean workshop and the chimney should not be less than 12 times the height of the chimney, and the distance between the clean workshop and the traffic artery should not be less than 50 meters. The clean workshop should be surrounded by greening, and lawns can be laid, trees that do not have a harmful effect on the dust content of the atmosphere can be planted, and greening areas can be formed, but fire fighting operations must not be hindered.

5. Clean workshop noise control

The noise level in the clean workshop should meet the following requirements:

• During dynamic testing, the noise level in the clean workshop should not exceed 65 dBA.

• During air testing, the noise level of the turbulent clean workshop should not be greater than 58 dBA, and the noise level of the laminar clean workshop should not be greater than 60 dBA.

• The plane and section layout of the clean workshop should take into account the requirements of noise control. Its enclosure structure should have good sound insulation performance, and the sound insulation of each part should be close.

• Low-noise products should be used for various equipment in the clean workshop. For equipment whose radiated noise exceeds the allowable value of the clean workshop, special sound insulation facilities (such as sound insulation rooms, sound insulation covers, etc.) should be set up.

• When the noise of the purified air conditioning system exceeds the allowable value, control measures such as sound insulation, noise elimination, and sound insulation vibration should be taken. In addition to the exhaust for accidents, the exhaust system in the clean room should be designed to reduce noise.

• The noise control design of the clean room must take into account the air cleanliness requirements of the production environment, and the purification conditions of the clean room must not be affected by noise control.

6. Clean room vibration control

• Active vibration isolation measures should be taken for equipment with strong vibrations (including water pumps, etc.) in the clean room and surrounding auxiliary stations and their pipes leading to the clean room.

• The comprehensive vibration impact of various vibration sources inside and outside the clean room on the clean room should be measured. If conditions are limited, the comprehensive vibration impact can also be evaluated based on experience. And it should be compared with the allowable environmental vibration value of precision equipment and precision instruments to determine the necessary vibration isolation measures.

• The vibration isolation measures for precision equipment and precision instruments should consider reducing the amount of occurrence and maintaining reasonable airflow organization in the clean room. When using air spring vibration isolation pedestals, the air source should be treated to achieve the air cleanliness level of the clean room.

7. Requirements for clean workshop construction

• The architectural plan and spatial layout of the clean workshop should have appropriate flexibility. The main structure of the clean area should not be supported by internal walls.

• The height of the clean workshop is controlled by the net height, and the net height should be based on a basic modulus of 100 mm.

• The durability of the main structure of the clean workshop should be coordinated with the indoor equipment and decoration level, and should have fire prevention, temperature deformation control and uneven settlement performance (seismic areas should comply with the anti-surface design regulations). The deformation dimension of the workshop should avoid passing through the clean area.

• When the supply and return air ducts and other pipelines need to be concealed, technical mezzanines, technical alleys or trenches should be set up; when the vertical pipelines passing through the polar layer need to be concealed, technical shafts should be set up.

• For comprehensive workshops with both general production and clean production, the design and construction of the scheme should avoid adverse effects on clean production in terms of personnel and logistics transportation and fire prevention.

8. Personnel purification and material purification facilities in clean workshops

Rooms and facilities for personnel purification and material purification should be set up in clean workshops, and living rooms and other rooms should be set up as needed.

Rooms for personnel purification should include rain gear storage rooms, management rooms, shoe changing rooms, outerwear storage rooms, washrooms, clean work clothes rooms and air showers. Living rooms such as toilets, showers, lounges, and other rooms such as work clothes washing rooms and drying rooms can be set up as needed. 

9. Fire prevention and evacuation in clean workshops

• The fire resistance level of clean workshops should not be lower than level 2. The ceiling material should be non-combustible, and its fire resistance limit should not be less than 0.25 hours.

• The fire hazard of general production workshops in clean workshops can be classified according to Appendix 3.

• For clean workshops of Class A and Class B production, single-story workshops are preferred. The maximum allowable floor area between fire walls is 3,000 square meters for single-story workshops and 2,000 square meters for multi-story workshops.

• For prefabricated clean workshops of Class A and Class B production or set up in Class A and Class B production environments, their ceilings and wall panels (including internal fillings) should be non-combustible.

• For comprehensive workshops in a fire zone, non-combustible partition walls should be set up to close the top between the clean production and general production areas. The fire resistance limit of the partition wall and its corresponding top plate should not be less than 1 hour, and the fire resistance limit of doors and windows on the partition wall should not be less than 0.6 hours. The gaps around pipelines passing through the partition wall or top plate should be tightly filled with non-combustible materials.

• The parallel walls of the technical shaft should be non-combustible, and their fire resistance limit should not be less than 1 hour. The fire resistance limit of the inspection door on the wall should not be less than 0.6 hours; in the vertical shaft, the floor slabs of each layer or the limit layer should be made of non-combustible bodies equivalent to the fire resistance limit of the floor slab for horizontal fire separation; the gaps around the pipelines passing through the horizontal fire separation should be tightly plugged with non-combustible materials.

• The number of safety exits in each production layer, each fire partition or each clean area of the clean room should not be less than two.

10. Indoor decoration of clean room

• The building envelope structure and interior decoration of the clean room should use materials with good air tightness and small deformation under the action of temperature and humidity changes. When the wall decoration needs to add a structural skeleton and insulation layer. Non-combustible or difficult-to-burn bodies should be used. The surface of the walls and ceilings in the clean room should meet the requirements of flatness, smoothness, no dust, avoid glare, and easy dust removal.

• The concave and convex surfaces should be reduced, and the bright and sunny corners should be made into the same fish. The interior decoration should be used for operation; if it is plastering, the advanced plastering standard should be adopted.

• The floor of the clean workshop should meet the requirements of being flat, wear-resistant, easy to remove dust and clean, not easy to accumulate static electricity, avoid glare, and have a sense of comfort.

• The walls and ceilings of the technical mezzanine of the clean workshop should be plastered. If it is necessary to replace the high-efficiency Air Filter in the technical mezzanine, it is advisable to add paint finishes. The ground, return air trench and technical mezzanine located underground should adopt waterproof or moisture-proof and anti-toxic measures. The inner surface decoration standards of the building air duct and return air trench should be compatible with the entire supply and return air system, and should be easy to remove dust.

• The external windows of the clean workshop and the personnel purification room should be double-glazed and have good air tightness.

• The closed doors in the clean workshop should be opened to the room with higher air cleanliness. An observation window should be set on the closed door of the windowless clean room.

• Reliable sealing measures should be taken for the structure and construction gaps of the doors, windows, walls, ceilings, and ground (floor) of the clean workshop.

• The colors in the clean workshop should be elegant and soft. The light reflection coefficient of indoor surface materials should be 0.6-0.8 for ceiling and wall; 0.15-0.35 for floor.

11. Clean room air purification

• When there are multiple processes in the clean room, different air cleanliness levels should be adopted according to the different requirements of each process.

• Under the premise of meeting the production process requirements, the air flow group level of the clean room should adopt the form of combining local work area air purification and whole room air purification.

• The Clean air conditioning systems of laminar clean room and turbulent clean room, as well as clean rooms with different operating shifts and use time, should be set separately.

• A certain amount of fresh air should be guaranteed in the clean room, and its value frequency takes the maximum value of the following air volume; 10%~30% of the total air supply of turbulent clean room, 2~4% of the total air supply of laminar clean room; the amount of fresh air required to compensate for indoor exhaust and maintain indoor positive pressure value; ensure that the indoor fresh air volume per person per hour is not less than 40 cubic meters.

• For the cleaning of clean areas, it is advisable to use mobile high-efficiency vacuum cleaners or set up centralized vacuum cleaning systems. The pipes of the centralized vacuum cleaning system in the clean workshop should be concealed.

• Requirements for construction and maintenance management in the design of the purified air conditioning system.

12. Water supply and drainage in clean workshops

• The water supply and drainage trunk pipes in the clean workshop should be installed in the technical mezzanine, technical shaft, trench pipe trough or buried underground.

• There should be a small number of pipes in the clean workshop. The branch pipes introduced into the clean room can be laid openly, but the clean workshop with high air cleanliness requirements can be concealed. If condensation is likely to occur, anti-condensation measures should be taken.

• Casings should be installed where the pipe passes through the ceiling, wall and floor of the clean workshop. Reliable sealing measures should be taken between the pipe and the casing.

• The pipe should not pass through the firewall. If it must pass through, the wall-penetrating pipe and its casing should be non-combustible pipes.

• Safety comes first in everything.