Dimensioning

CoPlasma® system – Normative aspects and dimensioning

Selection of the CoPlasma® system is made according to the final results required in the room or in the area in which the air contamination or purity has to be monitored and controlled. The development of the ducting installation and the air diffusion system adopted will be taken into consideration in order to allow an appropriate emission of cold plasma with micro-concentrations of ozone to obtain the required decontaminating effect.

The dimensioning is based on the following concepts:

  1. Calculation of the air flow based on thermodynamic parameters
  2. Dimensioning by room typology (schedule 1) or by class of contamination (schedule 2)
  3. Determination of the final number of air cycles in the room/environment considered and of the effective flow of air decontamination/treatment central (schedule 3).
  4. Dimensioning of the EF considering the flow.
  5. Dimensioning of the cold plasma emission system.
Table 1 Classification per food sector Filter efficiency Type of plant
  Min. Max.  
Dairy
Cheese ripening/maturing (semi hard and hard) 90 95 High efficiency filtration
Milk and Yogurt filling 90 95 Contamination control
Rooms in which product is not in direct contact with the environment 90 95 High efficiency filtration
Soft cheese cooling 99 99.5 Contamination control
Drying 99 99.5 Contamination control
Cheese packing 99 99.5 Contamination control
Yogurt production (open cups) 99 99.5
Meat
Processing 99 99.5 Contamination control
Packing/Canning 99 99.5 Contamination control
Sausages
Row Meat cold storage 90 95 High efficiency filtration
Drying 99 99.5 Contamination control
Seasoning and maturing 99 99.5 Contamination control
Storage 90 95 High efficiency filtration
Prosciutto (ham) drying 99 99.5 Contamination control
Prosciutto (ham) ripening and seasoning 99 99.5 Contamination control
Packaging 99 99.5 Contamination control
Poultries
Processing 99 99.5 Contamination control
Packaging 99 99.5 Contamination control
Fruit and vegetables
Storage 90 95 High efficiency filtration
Packaging 99 99.5 Contamination control
Classified environment ISO 5 & ISO 6 See Table 2 Pre-filtration

Table 2 Clean Rooms Classification

 Clean Area Classification

(0.5 μm particles/ft3)

ISO

Designationb

> 0.5 mm particles/m3 Microbiological Active Air Action Levelsc(cfu/m3 ) Microbiological Settling Plates Action Levelsc,d(diam. 90mm; cfu/4 hours)
100 5 3,520 1e 1e
1000 6 35,200 7 3
10,000 7 352,000 10 5
100,000 8 3,520,000 100 50

a-  All classifications based  on data measured in the vicinity of exposed materials/articles during periods of activity.

b-  ISO 14644 -1 designations provide uniform particles concentration values for cleanrooms in multiple industries.  An ISO 5 particles concentration is equal to Class 100 and approximately equals EU Grade A.

c-  Values represent recommended levels of environmental quality.  You may find it appropriate to establish alternate microbiological action levels due to the nature of the operation or method of analysis.

d-  The additional use of settling plates is optional.

e-  Samples from Class 100 (ISO 5) environments should normally yield no microbiological contaminants.

Example:

Let’s assume to handle a room of 1000m3 that need to maintain proper thermo-hygrometric condition an air flow rate of 7500m3/h. The room is destined to food packing and consequently is to be under Contamination Control.

Looking at table 3, air recirculation must be increase at a minimum level of 10 and consequently the minimum flow rate must be 10000m3/h. Thermo-hygrometric calculation must be consequently revised.

The efficiency required must be above 99.5%.

1-row2-row

From the diagram it is evident that, to reach the required efficiency, double rows (or ranks) must selected. The efficiency allows a flow rate per cell of 3300m3/h, consequently the number of EF cells required is 3+3. The efficiency with 3+3 cells in two rows on 10000m3/h air flow is 99.71%. We can use 1 row geometry with 5 cells in one line and the efficiency will be 99.18%, but this geometry probably will not fit in the air handling unit. So the selection is determined also by the housing in which the system will be located.

Table 3 Selection pre-filter Electrostatic filter Eff. ave% final Eff. %mpps Ricirc.
          Vol/h
Class A Room (ISO5) G4 ES1 95 U15 99.9995 250-500
Class B Room (ISO6) G4 ES1 95 H14 99.995 50-150
Class C Room (ISO7) G4 ES2 99.7 99.95 25-50
Class D Room (ISO8) G4 ES2 99.5 99.5 10-25
Contamination Control G4 ES2 99 10-25
High efficiency filtration G4 ES1 90 7-15
Pre-filtration G4 ES1 80
ES1 (Electrostatic 1row)            
ES2 (Electrostatic 2rows)            

Emitters step (m) based on the duct section S and air velocity

 S(m2)/Air V (m/s) 2 3 4 5 6 7 >7
<0.25 0.50 0.33 0.25 0.20 0.17 0.14 0.14
0.5 1.00 0.67 0.50 0.40 0.33 0.29 0.29
1 2.00 1.33 1.00 0.80 0.67 0.57 0.57
2 4.00 2.67 2.00 1.60 1.33 1.14 1.14
>4 8.00 5.33 4.00 3.20 2.67 2.29 2.29

To calculate the number of emitters (XEM or other models), in first approximation it must be taken into consideration the length of the ducts, the average duct section and the average air velocity. Considering as hypothesis a length of 100m, and average section of 500x500mm i.e. 0.25m2 and a speed of 5m/s the number of emitter is calculated as follow:

(from the table 0.25-5) 0.20 per meter of length * 100m and then 20 in total.

Further considerations must be taken to ionize air at outlet of the diffusion system.