Example of calculation method for cleanliness

In the design of the clean room, the Air volume required to ensure the required cleanliness and the air volume required for temperature and humidity adjustment must be calculated. Here, only the calculation method to ensure indoor cleanliness is listed. Assume the amount of dust generated in the room and the dust content of the fresh air, and use the following formula to calculate the cleanliness through ventilation air volume, etc. according to the efficiency of the Air Filter used.

Qr = room volume x ventilation times per hour

C: Indoor dust concentration (pieces/m3)

Qe: Exhaust air volume (m3/h)

Co: External air dust concentration (pieces/m3)

M: Indoor dust generation (pieces/h) Supply air dust concentration (pieces/m3)

Pt: Dust penetration rate (%)

Pf1: Pre-filter penetration rate (%)

Pf2: Main filter penetration rate (%)

Qr: Ventilation air volume (m3/h)

Qo: Fresh air volume (m3/h)(m3/h)

Qs: Air volume

The dust concentration in the outside air of Co is the number of particles of 0.5um in Table 2 or Table 3 above. )

The dust penetration rate of P is the penetration rate formed by the DOP aerosol of 13-14 kinds of dust in the JIS Z8901 test, expressed as (P=1-capture rate). )

The outside air volume of Qo should take into account the local exhaust of air supply and harmful substances stipulated in the environmental sanitation environment. In order to form a positive pressure in the room, the required air volume is calculated by the following formula.

• The ventilation volume of Qr is determined based on the cleanliness level and after considering the work content in Table 15.

• Since the indoor dust generation of M varies according to the work content, it is determined after referring to the operator dust generation in Table 5 or Table 6.

• In order to adjust the positive pressure in the room, a safety air valve damper should be installed to allow it to be discharged when the pressure rises.

Table 15 Ventilation frequency, fresh air volume and efficiency of end filters for cleanliness levels