Generally, the height of the old factory is about 3m, the area and shape are different from the actual need, and usually can not be installed in accordance with the conventional air duct, technical interlayer and special air conditioning system. According to the basic principles of air purification, in practice, we have explored a very practical technical transformation method of clean workshop, especially suitable for small and medium-sized clean workshop technical transformation. Here is the introduction:

1. Structure pattern

The principle diagram of transforming dust-free workshop by using ordinary air conditioner to send cold air directly to air main stream area. The dust-free workshop is built in the old factory building, the room height is 3m, the dust-free workshop wall is constructed with sandwich color steel plate, the height is about 2.4m, and the top of the dust-free workshop is the fan room, the height is about 0.6m, which is equipped with a fan box. All sides of the fan room are closed and equipped with a medium effect filter inlet for inward ventilation. The fan is installed in the fan box, the lower part of which is the plenum box and the filter. There is no return air primary filter on the lower side of the dust-free workshop, and the outside of the dust-free workshop is a return air sandwich, which is connected with each other, and there is at least one split type split air conditioner. The air conditioner can first use the ordinary cabinet type split air conditioner, the outlet is equipped with a diversion hood and a cold air pipe, and the other end of the cold air pipe is installed in the fan room. Under normal circumstances, the fan of the ordinary air conditioner can send the cold air to 15 m away, which can basically meet the use of the general small and medium-sized dust-free workshop. When the air supply distance is far away, the fan can be installed on the cold air pipe to increase the air supply pressure.

It should be noted that the deflector hood and the cold air pipe must be insulated. The thickness of the indoor unit of the ordinary cabinet split air conditioner is generally 0.25m~ 0.35m Taking into account the width of the diversion hood, the width of the return air sandwich can be made of 0.5m ~ 0.7m. When a wall-mounted air conditioner is selected, the width of the return air passage can be reduced, and the width of the remaining return air passage can be made into 0.1m. In this way, the design of the dust-free workshop can make use of the building space.

2. Air circulation mode

The air is sent into the plenum by the air, enters the dust-free workshop through the filter, and then enters the return air duct from the return air primary effect filter. Part of the return air flow and the fresh air from the fresh air primary effect filter enter the fan room through the medium effect filter, and the other part of the return air flow directly enters the air inlet of the air conditioner. After the air is cooled, the air enters the fan room through the guide hood and the cold air pipe. After the two parts are mixed in the fan room, they are sent to the plenum by the fan through the medium effect filter on the fan box, and then enter the dust-free workshop through the filter to form an air circulation system. From the circulation of the air flow, it can be seen that a good three-stage filtration state has actually been formed. Therefore, the air quality of the dust-free workshop is reliably guaranteed. On this basis, adjust the structure and layout of the filter air supply outlet, with the corresponding air volume, you can determine the clean form and cleanliness of the dust-free workshop to meet different needs.

DOP leak detection test for ultra-clean bench filter

Why do a DOP leak test on a filter on a super-clean table?

1. Overview

If there are defects in the filter and its installation, such as the filter itself has small holes or the installation is not tight to form small cracks, it will not achieve the predetermined purification effect. Therefore, after the filter is installed or replaced, it is necessary to check the leak between the filter and the installation.

2. Purpose of leak detection

By testing the amount of leakage in the filter, defects in the filter and its installation are found so that remedial action can be taken.

3. Leak detection range

Clean areas, laminar flow tables and filters on equipment.

4. Method of leak detection

Commonly used is the DOP method of leak detection (that is, the DOP solvent is used as a dust source, and the aerosol photometer is used to detect the leak), and the dust particle counter scanning method can also be used to detect the leak (that is, the atmospheric dust is used as a dust source, and the particle counter is used to detect the leak). Because the particle counter reading is cumulative reading, it is not conducive to scanning, and the inspection speed is slow; In addition, on the upwind side of the filter being measured, the atmospheric dust concentration is often low, and it is easy to find the leak by adding smoke, and these deficiencies of the particle counter method can be compensated by the DOP method, so the DOP method is widely used abroad for leak detection.

5. DOP method for leak detection

5.1. Working principle

The DOP aerosol is sent on the upwind side of the detected filter as a dust source (DOP is dioctyl phthalate, molecular weight 390.57, the particles are ball shaped after spraying), and the air sample is sampled on the downwind side by a photometer. The collected air sample passes through the diffusion chamber of the photometer, and the scattered light generated by the dusty gas passing through the photometer is converted into electricity by photoelectric effect and linear amplification. The relative concentration of aerosol can be measured by a microammeter. The DOP test actually measures the penetration rate of the filter.

5.2. Materials and instruments

① Dust source (DOP solvent);

② DOP generator [For the device to produce smoke, DOP solvent into the generator container, under certain pressure or heating conditions to produce aerosol smoke is sent to the upwind side of the filter (DOP liquid heating, the formation of DOP steam, steam condensation into tiny droplets under specific conditions, remove too large and too small droplets, leaving only 0.3μm or so particles, Fog DOP into the air duct);

(3) Aerosol photometer (measuring and displaying the aerosol concentration of the instrument, should indicate the verification period of validity, need to be verified and within the validity period can be used);

④ Nitrogen;

⑤ epoxy resin silica gel;

⑥ Spare filter of desired type

5.3. Working procedure of leak detection test

5.3.1. Prepare for leak detection

Prepare the equipment required for leak detection and the layout plan of the air supply pipeline of the purification air conditioning system in the area to be inspected, and notify the purification air conditioning equipment company to apply glue and replace the filter on the day of leak detection.