Ventilation Controls Level 4 Basic principals of Ventilation

Ventilation Controls Level 4: Basic principals of Ventilation Design, implementation and maintenance Part 1 of 2

Outline n n Approaches to ventilation systems Key features Good design considerations for local ventilation Inspection and maintenance 2

Two Main Types of Ventilation General/Dilution Heat control and/or removal of contaminants (dilution ventilation) Used for contaminant control ONLY when local exhaust is impractical Not effective or economical n n n Local Captures contaminants at source Preferred method of control – more effective – more economical Indirect exposure: general ventilation or control at source Direct exposure: local ventilation/ controls Most exposure is generally received directly 3

General Ventilation: Once-through System with 100% makeup air Appropriate filtration or treatment Appropriate Filtration H E P A 4

General Ventilation: Re-circulating System H E P A HEPA H E P A 5

General Ventilation: Re-circulating System - with ~10% makeup air 6

General Ventilation: Typical Ventilation Rates Chemical Operations or Labs: 15 OAC/hour Instrument or Biology Labs: 10 OAC/hour Rates Pharmaceutical Operations: 5 OAC/hour Offices: 1 OAC/hour OAC: outside air change 7

General Ventilation: Limiting Factors for Control of IH Exposures n Contamination levels must not be too high or air flow rate necessary for dilution will be impractical n Workers cannot be near contaminant source n Toxicity of contaminant must be low n Evolution of the contaminant must be reasonably uniform 8

General Ventilation Typical design failures n The air inlets are too close to the air outlet n The air will not circulate throughout the room 9

General ventilation recommendations operating vehicles indoors n n n propane-fueled lift truck - 2. 5 m 3/s gasoline-fueled lift truck – 4 m 3/s operating automobile – 2. 5 m 3/s operating truck - 5 m 3/s Other diesel-fueled vehicles 0. 05 m 3/s/horsepower 10

Local Exhaust Ventilation LEV Consider contaminant characteristics: n n n Gas / vapour /fume / particles Temperature Particle size Particle speed Directionality of source n The perfect solution for one situation will fail in another n The solution must be tailored to the source 11

Typical contaminant sources Source: BOHS 12

Typical contaminant sources Source: BOHS 13

Local Exhaust Ventilation: Hood Design Principles Main aspects influencing effective performance n n n Distance from source Enclosure design Design of openings Other aspects regarding velocity in the duct, duct design etc. are critical to a good functioning system, but won’t be covered here 14

Distance from source Rule of thumb: Distance from source should be diameter of opening or less Air speed at emission point is called capture velocity 15

Change in velocity with distance 16

Recommended Capture Velocity Source: ACGIH You can measure the capture velocity easily with an anemometer 17

Capture velocity and flow rate n At design, the flow rate is calculated to give the capture velocity you need 18

Effect of enclosure design: Hood capture velocity with and without flange n With flange Source : EPA 19

Effect of enclosure design: The airflow required to give effective control 1 m 3/s n Plain extract opening 0. 78 m 3/s n 0. 39 m 3/s 0. 74 m 3/s n Enclosure added at sides and above bench Flange added at rear n Transparent screen added at front BOHS 20

Effect of enclosure design: Hood entry loss coefficient for various duct design n Air enters the duct more smoothly and efficiently when there is an smooth angled entrance to the duct 21

Summary of Key Points affecting performance of LEV Increased enclosure greatly improves the effectiveness of the extraction 2. 1. The distance between the extract and the source must be similar to the dimensions of the extract 3. The design of the duct entrance should be smooth 22

Examples of LEV –Charging Fluid Bed Granulator Would you expect this to work? How would you improve it? 23

Charging Granulator – Improved Engineering 24

Example of LEV- Charging Excipients What is good and bad here? n n n This is an enclosure – but not ventilated The station is too small There is nor provision for waste disposal How would you improve it? 25

Charging Excipients - Improved design Integrated disposal of waste makes a big difference to exposure 26

Examples of LEV – Weighing operation n n Canopies never work for powders They even risk increasing the exposure for the operator Leave them in the kitchen, over hot surfaces, where they work 27

Examples of LEV – More weighing operation n n Not appropriate for this scale of weighing. . . but a lot better than this. The “local” extract is in the ceiling 28

Examples of LEV – larger scales weighing n The wall extract is likely to be very ineffective here - there is no “push” of air n There is also likely to be cross contamination between booths 29

LEV – laminar air flow booths n Laminar air flow booths can be good for Pb. OEL 1 and 2 compounds n Exposure can be reduced further with good orientation, good techniques, drum lifters, and additional screening n Pb. OEL 3 & 4 need more containment however 30

Laminar flow booth – typical design • A: • B Return duct directs air flow away from operator • C • D Filter/Fan Units – create positive pressure of filtered air • E Air Handler – exhausts air to create a negative pressure Filter/fan unit (HEPA or ULPA) Exit filters (HEPA or ULPA) 31

Worker orientation in laminar air flow booth n Tests showed an improvement of a factor of 2000 in large laminar air flow booths Source: ACGIH 32

Design guidance n A selection of drawings from the ACGIH manual follow, showing recommended designs. Further details are provided in the manual 33

Glove Box For High Toxicity Materials (ACGIH) ACGIH Ref. no. 34

Typical Isolator n Excellent protection is provided by an isolator – but the design still influences the performance 35

Weigh Hood, Powders (ACGIH) 36

Drum Filling (ACGIH) 37

Typical Laboratory Hood 38

Grinding Wheel Hood n The manual includes details on flow rates for various week sizes. n No more than 25% of the wheel should be exposed 39

Evaluation – smoke tubes n Smoke tubes/generators help to visualise the air movement and can be a good indicator of performance n They are useful in training operator in how their behaviours influences exposure n The LEV may appear better than it is, as the smoke is diluted in the air 40

Evaluation – measurement of capture velocity n Capture velocity is measured with an anemometer n Compare it with recommended / design values n Face velocity can also be measured, compared with design values and used to calculate the air flow 41

Periodic Inspection and Maintenance n A detailed plan of periodic maintenance of both general and local ventilation must be established and adhered to n The objective is to verify that – the system is performing to specifications – Proper maintenance, cleaning and chemical treatment (if necessary) is undertaken to inhibit growth of microorganisms in the complete ventilation system – Any faults, abraded surfaces contamination are detected and corrected. – acceptable quality of air is entering the structure n The periodic maintenance frequency will vary with task but is typically quarterly 42

Conclusion n There are two main approaches to ventilation, general and local n With hazardous substances, local ventilation is preferred n Simple considerations in design and use greatly increase the effectiveness n Recommended designs are given in the ACGIH ventilation manual n Ventilation systems must be regularly inspected and maintained 43

Exhaust Ventilation Level 4: Special considerations with very hazardous substances Part 2 of 2

Outline n Overview of main ventilation controls for very hazardous substances n Testing for ventilated enclosures 45

Very Toxic Substances n Active Pharmaceutical Ingredients / Isolated Process Intermediates (APIs/IPIs), usually Pb. OEL 3 B and 4 n The “gens”: Carcinogens / Mutagens / Reprogens n IDLH : Immediately Dangerous to Life and Health n The use of ventilation controls must be managed very carefully when very toxic substances are handled 46

Ventilation systems The systems most commonly used for handling of very hazardous substances are: n n n Laminar air flow booths Vented balance safety enclosures Glove box isolators 47

Key Point for very toxic substances Ventilation systems that are essential to the safe operation of a process or procedure must be equipped with automatic warning systems which are activated when the ventilation system fails to meet required performance criteria. 48

Laminar Flow Booth n n Typically re-circulate air Pre-filter and HEPA filters required Built-in alarm system Very limited for very toxic substances – additional controls must be implemented 49

Limitations of a Laminar Flow Booth n Requires supplemental PPE for Category 3 n Standard design protects against particulate n Special design needed for solvent handling n Exposure is very dependant on operator technique 50

Vented Balance Safety Enclosure Examples: weighing/transferring and manipulating milligram amounts of neat drug and lyophilized product 51

Vented Balance Safety Enclosure – more examples n n n HEPA filtered exhaust Connected to house system Smaller size mainly suitable to laboratory work 52

Glove Box Isolators • weighing/transferring and manipulating gram or higher amounts • Suitable for manufacturing activities 53

Isolators Alarm n n n Can also be mobile unit HEPA Filtered Exhaust Connected to house system 54

Limitations of Isolators n Size of material handled n Bringing material in/out n Risk of back and shoulder strain with prolonged use – Must include ergonomics in design n May be residual risk with material outside isolator 55

Test before every use n n Inspection and pressurisation test must be undertaken before each use Cease operation if alarm sounds All pressure gauges must be in “green” Check gloves are all in underpressure 56

Testing of Isolators n n n Installation Qualification (IQ) Test on installation Operations Qualification (OQ) Test as part of periodic maintenance Inspection undertaken prior to each use Frequent pressurisation tests The equipment should not be used if the equipment fails any of these test or if an alarm sounds during operation. 57

Installation Qualification Test n Main elements – – Define systems Review drawings and documentation Review installation Check all parts 58

Operational Qualification Test n Main Elements – – – – key component check inflow velocities HEPA filter integrity Filter pressure drops/magnehelic gauges Illumination and noise levels Motor Alarms 59

Summary n Great care must be taken in control of exposure to very hazardous substances n All equipment for very hazardous should be fitted with alarms n Regular testing must be scheduled and documented 60