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Air Flow Analysis in Pharmaceutical Clean Rooms Patrick Phelps ( Flowsolve ) and Richard Rowe ( Clean Room Construction Ltd ) IPUC 8 - Luxembourg - May.

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Presentation on theme: "Air Flow Analysis in Pharmaceutical Clean Rooms Patrick Phelps ( Flowsolve ) and Richard Rowe ( Clean Room Construction Ltd ) IPUC 8 - Luxembourg - May."— Presentation transcript:

1 Air Flow Analysis in Pharmaceutical Clean Rooms Patrick Phelps ( Flowsolve ) and Richard Rowe ( Clean Room Construction Ltd ) IPUC 8 - Luxembourg - May 2000

2 Air Flow Analysis in Pharmaceutical Clean Rooms b Industrial Context b Health and Safety Issues b Application to an Existing Room b Application to New Ventilation Designs b Conclusions b Experimental Verification

3 Clean Rooms Areas concerned with the preparation, processing and packaging of pharmaceutical products b Strict codes of practice employed to eradicate risk of product contamination

4 Clean Rooms b Personnel access controlled b 2-layer sterile over-clothing b Equipment sterilised before entry b Strict cleansing procedures b Particular attention to ventilation

5 Ventilation of Clean Rooms b Design and performance of air supply, filtration, and extraction arrangements must meet exacting standards Positive pressure areasPositive pressure areas Use of Laminar Flow Units (LFUs)Use of Laminar Flow Units (LFUs)

6 Laminar Flow Units Laminar Flow Units Devices which deliver a controlled down-draught of re-filtered air over sensitive regions preparation areaspreparation areas processing areas processing areas packaging areaspackaging areas storage areasstorage areas

7 Air Flow Analysis in Pharmaceutical Clean Rooms

8 CFD Application to Air Flow Analysis in Clean Rooms Context Upgrade of ventilation system in a suite of clean rooms at a UK pharmaceutical company

9 CFD Application to Air Flow Analysis in Clean Rooms Objective Use CFD to ensure exacting requirements can be met, following installation of a can be met, following installation of a number of LFUs. number of LFUs.

10 CFD Application to Air Flow Analysis in Clean Rooms Workscope 3 rooms selected as representative examples of areas being upgraded Room 30Room 30 Room 23Room 23 Room 42Room 42

11 Modelling Considerations - 1 b Irregular shaped domains b Internal Obstructions to flow b Cartesian grid employed b K-e (Chen) turbulence model used b Buoyancy important in transient b (otherwise assume isothermal)

12 Modelling Considerations - 2 Dependent variables solved pressure, ppressure, p lateral velocity component, Ulateral velocity component, U vertical velocity component, Vvertical velocity component, V Longitudinal velocity component, WLongitudinal velocity component, W Turbulence kinetic energy, kTurbulence kinetic energy, k Turbulence energy dissipation rate, eTurbulence energy dissipation rate, e residence time parameter, t resresidence time parameter, t res (temperature, T (for transient)(temperature, T (for transient)

13 Modelling Considerations - 3 Boundary Conditions b Air supply ducts prescribed sources of mass, momentum, turbulence and residence timeprescribed sources of mass, momentum, turbulence and residence time b Air Extract ducts specified fixed-pressure outlet sinksspecified fixed-pressure outlet sinks b LFUs inlets and outlets specified as aboveinlets and outlets specified as above

14 Representation of LFUs b Air flow in individual units not solved b treated as internal blockages in domain b air discharged from base at prescribed rate b matching intake from front face b interactive updating of discharge residence time b constant internal residence time assumed

15 Room 30 b Small room x 5.94 x 2.92 m. b Used for processing, filling and packaging of products b Contains central plinth with filling- machine enclosure above b Conveyor-linked trays outboard of enclosure, for containers & finished goods

16 Room 30 - Before Room 30 - Before

17 Room 30 Simulations b Steady flow patterns before b Steady flow patterns before LFUs in enclosure onlyLFUs in enclosure only b Steady flow patterns after b Steady flow patterns after following fitment of 10 new LFUsfollowing fitment of 10 new LFUs b 75,000 node 3-D model Distribution : 50 x 30 x 50Distribution : 50 x 30 x 50

18 Room 30 - After Room 30 - After

19 Room 30 Simulations Objectives b Check for dead zones b ensure ventilation criteria met Criteria b 25 Air changes per hour b (residence time 144 seconds)

20 Room 30 - Sectional Planes

21 Room 30 - Before Room 30 - Before

22 Room 30 - After Room 30 - After

23 Room 30 - Before Room 30 - Before

24 Room 30 - After Room 30 - After

25 Room 30 - Before Room 30 - Before

26 Room 30 - After Room 30 - After

27 Room 30 - Before Room 30 - Before

28 Room 30 - After Room 30 - After

29 Room 30 - Before Room 30 - Before

30 Room 30 - After Room 30 - After

31 Room 30 - Before Room 30 - Before

32 Room 30 - After Room 30 - After

33 Room 30 - Before Room 30 - Before

34 Room 30 - After Room 30 - After

35 Room 30 - Before Room 30 - Before

36 Room 30 - After Room 30 - After

37 Room 30 - Before Room 30 - Before

38 Room 30 - After Room 30 - After

39 Room 30 - Before Room 30 - Before

40 Room 30 - After Room 30 - After

41 b Complex flow paths between inlet and outlet b Pattern complicated by LFU intake extraction flows b air has to pass around central plinth and filling-machine enclosure b air in near-side passage has to run gauntlet of LFUs Room 30 Ventilation Summary (after refurbishment)

42 b Outflow-weighted residence time of 121 seconds meets client criterion b near extract air considerably older than far extract air b some dead zones still apparent b evidence of entrainment into more than one unit Room 30 Ventilation Summary (after refurbishment)

43 Dead Zones - before Dead Zones - before

44 Dead Zones - after Dead Zones - after

45 LFU intake times - 1

46 LFU Unit intake times - 2

47 LFU Unit intake times - 3 b Units D1, D2, B2, C2, A1 receive considerably fresher air than their neighbours A2-A4, B2 and C1 b Air entering A4 is 2.2 times older than that entering D1 b Air leaving A4 exceeds air-change criterion en route to outlet

48 Conclusions b Residence time analysis concept adds considerable value to vector and contour plots in assessment of complex ventilation flows.


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