Selection and management of air conditioning filter in painting shop?

Abstract: Dust in the air is the enemy of coating. Dust with particle size greater than 5μm mixed into the paint layer can make the surface of the paint film to produce concealer points visible to human eyes. Therefore, appropriate dust-proof measures must be taken to reduce the concentration of dust in the air supply, so as to ensure the cleanliness of the air around the spraying process and obtain excellent film. It is one of the effective measures to select and configure the filter reasonably for the air supply system of the process air conditioning in the painting shop, and to maintain and manage it correctly.

The configuration of filter system with different coating requirements is introduced, and the selection and daily management of filter are proposed. Key words: painting shop process air conditioning filter selection management CLC Number: TB484 Document ID: B Different painting types have different requirements for the production environment. According to the dust control requirements of the painting shop, selecting, configuring and correctly maintaining and managing the filter for the air supply system of the process air conditioning is not only one of the preconditions to ensure that the air cleanliness of the painting shop meets the production requirements, but also can reduce the operating cost of the air conditioning system, so as to achieve the purpose of energy saving.

Dust in the air not only refers to dust, but also includes all kinds of organic matter that may be attached to the coating film, which will have an adverse impact on the performance of the coating film (such as durability, etc.). Table 1[1] is the air supply quality benchmark of the painting room excerpted from the Painting Workshop Design Manual. It can be seen from Table 1 that it is not accurate to think that the cleanliness of the spray painting room in the painting workshop should reach class 100,000 or even class 10,000. The dust quantity index to be controlled by the spray painting room in the design is far lower than the federal standard FS-209E Class 100,000 (international standard ISO 14644-1ISO8).

2. Configuration of the filter for the supply air system of process air conditioning At present, there is no relevant standard for the air cleanliness level of the spray paint room. G3-F5-F8-F5 (top cotton) filter configuration is often used for process air conditioning in newly built painting workshop (see Figure 1), but is this configuration reasonable?

3· Precautions for filter selection [4] When customers purchase new filters, they often directly provide the filter model and specifications selected by the previous design unit/construction unit to the air filter supplier, which has two disadvantages.

(1) In the design of the air conditioning system, some designers will slightly increase the configuration level of the air filter in order to ensure the standard of the workshop air cleanliness during debugging operation. If the filter is always selected according to the original requirements during the long run, it will increase the cost. Moreover, filter suppliers do not know the real needs of customers. If the product type on the customer demand list is directly used without considering the on-site air volume and installation environment requirements, the filter is prone to be blown or the air volume is reduced due to the filter resistance is too large because of the different manufacturers, materials and manufacturing processes of the original filter.

(2) The air volume of different air conditioning units and the number of configured filters are different. After receiving orders, the filter suppliers often make them according to the order requirements and conventional processes and materials. In this way, the mismatch between the air filter supply volume of the system and the filter type sometimes occurs, resulting in inconvenience for customers. In order to avoid the above problems, it is recommended that customers select filters.

Consider the following factors.

a. Compare the product samples of different filter manufacturers and select the one with low filtration resistance as the candidate supplier in the same model specification/filtration level.

b. Let the filter supplier investigate the site environment as far as possible, or provide detailed air conditioning system parameter table (such as the air volume in use and the design allowable resistance of the filter section, etc.), and the supplier shall provide the corresponding filter system configuration and product technical parameters.

c. Require the supplier to provide the performance test report of the product to confirm whether the requirements are met. 4. Maintenance and Management of filters The main performance indicators of filters are filtration efficiency and resistance. The filtration efficiency is directly related to the air quality entering the workshop, while the resistance affects the wind balance of the entire air conditioning system. After the air conditioning system runs for a period of time, dust will accumulate on the filter, increasing the air resistance, resulting in reduced or no wind. The decrease of air volume will reduce the number of indoor air exchange and affect the indoor cleanliness effect; However, the wind makes the filter without any filtering effect, resulting in the imbalance of wind balance at the painting site. It can be seen that although the filter accounts for a small proportion in the annual purchase, it has a great impact on the air conditioning system, so the maintenance and management of the filter should be attached great importance. The following work should be done.

a. When installing the filter, check whether the filter is in good condition and the installation direction is correct, and record the initial resistance of the filter.

b. Establish a daily differential pressure recording system for the filter, and check the appearance of the filter regularly during use.

c. Replace the filter in time when the filter resistance reaches near its recommended final resistance. d. Most filters are disposable (or cannot be cleaned, or are not economically worth cleaning).

5. Conclusion Correct selection and management of the filter can reduce the cost of repeated replacement of the filter during operation. At the same time, the reasonable configuration of the filter will reduce the internal resistance of the machine, thus reducing the required motor power, and saving the project cost and operation cost for each user