Frequently Asked Questions About Primary, Medium, High Efficiency Air Filters In Cleanrooms (2)

10. What are the standard dimensions and acceptable deviations of the diagonals of primary, intermediate, sub-high, and high-efficiency filters?

The standard diagonal of the primary, medium, and high-efficiency filters is the sum of the squares of the two right-angled sides, and then the square root: find the standard size of the oblique line, that is, the standard diagonal. The allowable deviation of the general filter is: for a filter greater than 700mm, the allowable deviation of the diagonal is less than or equal to 4.5mm, and for a filter less than or equal to 700mm, the allowable deviation of the diagonal is less than or equal to 2.3mm.

11. What are resistance, initial resistance, and final resistance?

Resistance: The fibers deflect the airflow, creating a small amount of resistance. The sum of numerous fiber resistances is the resistance of the filter.

Initial resistance: the air resistance when the tested filter without dust accumulation passes through the rated air volume.

Final resistance: refers to the rated air volume, due to dust accumulation in the filter, the initial resistance rises to the specified value, generally twice the initial resistance, or recommended by the manufacturer, and the unit is expressed in Pa.

12. What is the proportion of atmospheric dust, artificial dust, and artificial dust?

Atmospheric dust refers to the suspended particles contained in the outdoor or indoor natural air connected to the outdoor, while artificial dust is mainly composed of road dust, carbon black, and short fluffy cotton, and its composition ratios are 72%, 25%, and 3%, respectively. % and so on.

13. What are the test filter and terminal filter?

A filter whose performance is tested against a standard is called a filter under test.

The end filter refers to the filter used to trap the artificial dust of the filter under test.

14. What is the rated air volume? What is dust holding capacity?

The processing air volume designed by the filter per the unit time specified by the manufacturer, expressed in m³/h, and the dust holding capacity refers to the total mass of artificial dust applied when the tested filter reaches the final resistance and the average of the tested filter. The product of gravimetric efficiency is expressed in "g".

15. What are the standard folding numbers of high-efficiency filters with clapboards, and the factors that affect and determine their folding numbers?

The standard folding number of the high-efficiency filter with partition is determined by two important factors, such as the height of the partition paper and the tightness of the partition paper and filter paper when assembled. For example, the standard folding number of a wooden frame (610*610*120) mm³ type filter is: first remove the thickness of the wood on both sides, then 610-(20*2)=570mm, and the interval is 570÷4÷ 2=71.25% off, the result is about 70~72% off.

16. What is the frame and support of the filter?

The frame of the filter refers to the object that holds the filter material, maintains the shape of the filter, and bears the external force during the filter.

What does support mean? The part that supports the filter material or keeps the air passage between the filter materials in a certain shape.

17. What is a clean room, cleanliness, and local space purification?

Clean room refers to the room and area that require environmental control for dust particles and microbial contamination.

Local space purification refers to only making the concentration of suspended particles in the specific local space of the indoor working area reach the specified air cleanliness level.

Cleanliness refers to the allowable statistical number of suspended particles greater than or equal to a certain suspended particle in a unit volume of air in a clean environment.

18. What are the two test states of the filter? How to test air filters and how to test filter efficiency?

The test status of the filter is a dynamic test and a static test.

Filter testing methods are the sodium flame method and the oil mist method.

The test methods for filter efficiency include the atmospheric dust test method and the artificial dust test method.

19. What is the dust concentration? How to sample in the clean room (area) and how to evenly arrange the sampling points? How to judge the level of clean room (area)?

Refers to the quantity or mass of suspended particles contained in a unit volume of air.

When the unit is expressed in "grain/liter", it is called counting concentration; when the unit is expressed in mg/m³, it is called weight concentration.

Sampling in the clean room, the sampling position should be evenly arranged on the horizontal plane at a height of 0.8m from the ground. When there are more than 5 points, they can also be arranged in layers at a height of 0.8m~1.5m from the ground. When sampling, the air supply volume and pressure difference should be determined, and the return air outlet should be avoided. The arrangement of sampling points in the clean room should be uniform to avoid sparse sampling points in a certain local area.

Judging the clean room level is based on the following two conditions:

The average particle concentration of each sampling point must be lower than or equal to the specified level limit, that is, Ai≤level limit.

The 95% upper confidence limit of the mean value of the mean particle concentration of all sampling points must be lower than or equal to the specified level limit, that is, UCL≤level limit.

20. What are the principles and appearance requirements for the dimensions of the air filter?

The principle of expressing the dimensions of the air filter is: the airflow passing direction is the depth, the vertical length is the height when the vertical plane of the airflow passing direction is correctly installed, and the horizontal length is the width.

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