In order to obtain a good cleansing effect, the clean room should not only focus on adopting reasonable air-conditioning purification measures, but also require corresponding measures in the process, construction and other professions: not only must there be reasonable design, but also carefully conform to the standard construction and installation. And the correct use of clean room and scientific maintenance management. In order to achieve good results in clean rooms, many literatures at home and abroad have been elaborated from different angles.
In fact, it is difficult to achieve ideal cooperation between different professions, and it is difficult for designers to grasp the quality of construction and installation and the use and management, especially the latter. As far as clean room cleaning measures are concerned, many designers, or builders, often do not pay enough attention to the necessary conditions, resulting in unsatisfactory cleanliness. This article briefly discusses the four necessary conditions for achieving cleanliness requirements in clean room purification measures.
First, the air cleanliness:
To ensure that the cleanliness of the air supply meets the requirements, the key is to clean the performance and installation of the final filter of the system.
The final stage filter
of the purification system generally uses a high efficiency filter or a sub-high efficiency filter. According to China's standard , the efficiency of high-efficiency filter is divided into four grades: Class A is ≥99.9%, Class B is ≥99.9%, Class C is ≥99.999%, Class D is (for ≥0.1μm particles)≥99.999% ( Also known as ultra-high efficiency filter); sub-high efficiency filter  is (for ≥0.5μm particles) 95~99.9%.
The higher the efficiency, the more expensive the air shower filter
. Therefore, when selecting a filter, it should be in accordance with the requirements of air supply cleanliness and economic consideration. In view of the cleanliness requirements, the low-grade clean room is selected as a low-performance filter, and the high-grade clean room is selected as a high-performance filter. Generally speaking: 1 million grades can choose high-efficiency filter; below 10,000 grades can use sub-high efficiency or class A high-efficiency filter; 10,000-100 grades use B-type filter; 100~1 grade use C-type filter . There seems to be two types of filters to choose from for each cleanliness level. The choice of high performance or low performance depends on the specific situation: when the environment is seriously polluted, or the proportion of indoor exhaust is large, or the clean room It is especially important that a large safety factor is required. In either or both cases, a higher type of filter is selected; instead, a lower performance filter can be selected. For a clean room where 0.1 μm particles are required to be controlled, a Class D filter should be selected regardless of the controlled particle concentration.
The above mentioned only from the filter point of view, in fact, to select the filter should also fully consider the clean room characteristics, filter characteristics and purification system characteristics.
To ensure the cleanliness of the air supply, only qualified filters are not enough, but also to ensure that: a. transportation, installation process does not damage the filter; b. tight installation. To achieve the first, the construction and installation personnel are required to be well trained. They must have knowledge of installing the purification system and have more skilled installation skills.
Otherwise, it will be difficult to ensure that the filter will not be damaged. This is a profound lesson. . Secondly, the installation tightness problem depends mainly on the quality of the installation structure. The design manual  generally recommends: the surface of the single filter is mounted, so that even if leakage occurs, it will not leak into the room; Strictness is also easier to guarantee. For the air filter of a plurality of filters, a liquid tank seal and a negative pressure seal are often used in recent years.
The tank seal must be such that the joints of the tank are tight and the overall frame is at the same level. The negative pressure seal is to make the outer circumference of the filter and the static pressure box and the frame joint under negative pressure. Even if it is leaked, it will not leak into the room. In fact, as long as the installation frame is flat, the end face of the filter is evenly contacted with the mounting frame, and it is not difficult to achieve any