Procedure: Managing fume exhaust system

Purpose

The purpose of this procedure is to define the requirements for managing fume exhaust systems in laboratories at the Australian National University (University). The managing fume exhaust system procedure ensures that legal and other obligations of the Work Health and Safety Act, 2011 (Cth), and the Work Health and Safety Regulations, 2011 (Cth) are defined for managing the health and safety of all workers. This procedure is linked to the University’s Work health and safety (WHS) policy and is one of the safe work procedures within the WHS Management System.

Definitions

Filter is a device for the removal of contaminants from the air stream. High Efficiency Particulate Air (HEPA) filters are used to remove dust, fine particulates, and biological agents. Activated Carbon filters are used for the removal of organic vapours.

Fume cupboard is a five-sided exhaust hood for the capture, dilution and exhausting of laboratory emissions, especially those that are hazardous. The efficiency and safety of a fume cupboard depends upon the smooth entry of air, effective containment and scavenging of the emission from the chamber, and its safe and remote dispersal into the atmosphere. The effectiveness and efficiency of a fume cupboard also depends upon its location, laboratory ventilation and nearby turbulence, and if fitted, the cleaning system (e.g. scrubber or filter).

Fume exhaust system is any system comprising of a capturing hood, duct, fan and exhaust outlet used for the removal of hazardous or noxious gases, vapours, mists, dusts and other aerosols from a work environment, store or apparatus.

Fume hood is a device mounted above a work area to receive or capture an emission. It provides little or no enclosure of the workspace and is therefore unable to attain the containment of a fume cupboard.

Inspector is a person responsible for the testing, inspection or maintenance of a fume exhaust system.

Laminar (air) – flow is a non-turbulent airstream of constant velocity, substantially uniform over its cross-sectional flow.

Local area refers to a College, Research School or Service Division of the University.

Logbook contains information regarding the type of cupboard, safe operation, design characteristics, cleaning system, maintenance checks and repairs and performance test results. Logbooks are kept with the fume exhaust system. An example logbook is accessible via the Policy Library. A clear plastic sleeve fixed to the exhaust system (e.g. fume cupboard face) with loose-leaf sheets is acceptable as a logbook.

Make-up air is the air needed to replace the air that is removed from the room by the fume exhaust system.

Operation is a task, process, mechanism or equipment capable of generating a hazardous or noxious emission.

Sash is the transparent safety screen between the work chamber and the operator. It can be adjusted vertically (or horizontally) to vary the size of the working aperture.

Scrubber is a wet air cleaning technique or equipment for the removal of water soluble contaminants (e.g. acid gases, biological agents) and some dusts from the exhausted air. In general, they involve spraying an aqueous solution onto a coarse filter material (increasing the water to gas contact area) within the airflow. The contaminant adheres to or dissolves into the aqueous solution where it is physically or chemically removed from the air stream.

Services are the supplies (of lighting, electricity, water, and compressed gases etc.) that are available in the fume cupboard.

Site contact is the person a contractor liaises with to get access to an area and to inform of any deficiencies. This person is the business, laboratory or workshop manager or the safety officer.

A Worker is anyone who carries out work for the University. A worker includes staff, volunteers, contractor, students and visitors at the University.

Procedure

Scope

1. This is the University procedure for approving, purchasing, installing, using, and maintaining fume exhaust systems. A fume exhaust system is any system with a capturing hood, duct, fan and exhaust outlet that removes hazardous or harmful gases, vapours, mists, dusts and other aerosols from a work environment, store or apparatus to reduce potential hazards such as accumulating explosive gases.
2. The University has classified fume exhaust systems according to Australian Standards (AS)/ New Zealand Standards (NZS) 2243.8:2014.Refer to Table 1.

Emergency information

3. Direct emergency queries should be made to the local area management then Work Environment Group (WEG), HR Division (x52193). Local area management is responsible for coordinating any Emergency Services response. After-hours, contact ANU Security (x52249).

Responsibilities

4. Workers are responsible for using the correct type of fume cupboard for the work, process, or activity they wish to undertake.

For direct enquiries on the suitability of the system contact the Building Safety Officer, Work Health Safety (WHS) Committee or the WHS Officer;

• operating the system safely as with manufacturer’s requirements, refer to The safe use of fume cupboard guideline;
• designing and setting up their laboratory experiment to ensure they minimise any hazardous emissions and that any release occurs in a controlled manner;
• cleaning the workspace before any maintenance;
• updating the logbook;
• reporting any faults or incidents;
• regularly checking for laboratory standards; and
• lowering the sash when not working at the fume cupboard.

Note: A variable speed fume cupboard works most efficiently when the sash is down, reducing the tempered air being exhausted, saving electricity associated with heating and cooling costs and hence reducing greenhouse gas emissions. Not only will lowering sashes save money (approximately $400,000 a year across the University), laboratories are more comfortable and safe.

5. The responsible person for the local area or delegated representative is responsible for:

• ensuring the operation of the scrubber (if fitted) is checked in accordance with the manufacturer’s requirements (or at least twice annually) to ensure the scrubber is functioning correctly;
• updating the logbook;
• carrying out random checks on chemical usage to ensure that it complies with the fume cupboard grading;
• consulting the WEG Representative (via whs@anu.edu.au) on proposed changes to the location and/or classification of fume exhaust systems; and
• assisting in the notification of maintenance work to be conducted on fume exhausts systems.

6. The maintenance contractor is responsible for:

• conducting general inspections and maintaining the fume exhaust system;
• updating the logbook after completing any work; and
• accessing rooftops, roof and ceiling spaces or confined spaces in accordance with the University's policies and procedures.

Note: Standard Safe Operating Procedures are available from the local contact person.

7. The University (Local area) WHS Officer is responsible for:

• liaising with the responsible person or delegate representative and WHS Committee on all aspects of the fume exhaust systems;
• classifying the fume exhaust system, according to the classification system in Appendix 2 of AS/NZS 2243.8:2014;
• assessing the fume cupboards for upgrade under the Facilities & Services Division upgrade program; and
• inspecting the system and confirming details of any failed performance test in the event of any dispute.

8. The Facilities & Services (F&S) Division, is responsible for:

• liaising with building designers and constructors to ensure they follow this procedure;
• managing, installing and commissioning new or upgraded fume exhaust systems;
• responding to maintenance requests;
• conducting or arranging six-monthly and annual maintenance routines as described in Part 4 of AS/NZS 2243.8: 2014;
• conducting or arranging yearly checks, including performance tests under AS/NZS 2243.8: 2014;
• labelling the fume exhaust system with the correct signage; and
• maintaining the building's ventilation design plans and features.

Fume exhaust system classification

9. Table 1 describes the various classifications of fume exhaust systems.

Table 1: Classification of fume exhaust systems

Fume exhaust system approval

10. Table 2 describes the method for approving and buying a new fume exhaust system or varying an existing unit.

Table 2: Method of approving or buying fume exhaust system

Installation of a fume exhaust system

11. Table 3 describes the installation and acceptance of the fume exhaust system.

Table 3: Installation and acceptance of fume exhaust system

12. Fume cupboards should meet the requirements of AS/NZS 2243.8 Safety in Laboratories - Fume cupboards.

Exception: The minimum discharge height may be reduced to at least one metre above the ridge of a pitched roof or at least 1.8 metres above the deck of a flat roof.

Note: Installations in new buildings should comply with the Australian Standard at the time of construction. Any deviation from the Standard must be approved by WEG.

Fire precautions

13. Fume exhaust systems are occasionally used for some tasks where there is a significant risk of fire. Risks should be reduced to as low as reasonably practicable (ALARP) at the source following good practise. Controls may include:

• using minimum quantities of chemicals;
• condensers on distillation apparatus or for solvent evaporation; and
• distillation in an inert atmosphere (e.g. under nitrogen).

14. At the University, a fume exhaust system (a fume cupboard) is not generally fitted with fire detection or suppression systems due to issues with the reliability of components operating in the exhaust stream. At the initial evaluation of the Fume Exhaust System Request Form, the hazard assessment will determine if a fire detection and/or suppression system is required. If required then consider:

• the technical and practical effectiveness, within such environments with the aim of minimising false alarms and system failures;
• including a thermal detector. The detector should be linked to the building's emergency control panel, or to a local audible and visible alarm and activate at no more than 60 ºC;
• being capable of automatically isolating electrical power and flammable gas services to the fume cupboard. A thermocouple or water-flow detector may be suitable for this; or
• including a misting water sprinkler. The sprinkler head is fitted in the fume cupboard throat to protect the exhaust duct by cooling any hot gases drawn into the exhaust.

Warning: The sprinkler can not be linked to the main sprinkler system.

• Any fire detection/suppression system should be inspected at least yearly.

15. The University's Fire Safety Officer must assess fire suppression for new installations and the requirements of the items above.
16. In buildings with a sprinkler system, a fire sprinkler head should be within one metre of the front of the fume cupboard or within the worker's area.
17. A fire extinguisher must be available near the work area under AS/NZS2243.8, Section 2.14.3, Fire extinguishers.
18. The user should act to limit emissions through the proper design and control of the experiment or process. Emissions do not exceed the occupational exposure guidelines.
19. The Local Area and WHS Branch, WEG may request details of an experiment or process at any time to confirm the emissions don’t exceed the occupational exposure guidelines.
20. Inspection, testing and maintenance may take one of several forms:

• periodic cleaning of the fume cupboard by users, regularly and before periodic maintenance;
• periodic maintenance;
• performance testing; and
• specific inspection, testing, and maintenance, especially of filters.

General maintenance principles

21. The following general maintenance principles apply:

• general maintenance is the responsibility of F&S, although local areas may take on minor maintenance;
• before maintenance begins, place a sign near the controls (or on the fume cupboard sash) as ‘system under maintenance’ signage, ensuring the sign is removed when finished;
• the user removes all chemicals from fume cupboards or where not practicable ensure container caps are closed; and
• isolate fume cupboards from the power supply to prevent operation; and
• record all maintenance in the exhaust systems logbook.

Note: A similar process that meets the aim of protecting workers on the roof and notifying relevant staff\students is also acceptable.

Periodic cleaning of fume cupboards by the users

22. Regularly and before maintenance operations, fume cupboards must be cleaned to:

• improve their life and performance; and
• ensure they are free of risk to users and maintenance staff.

23. The following protocol applies.

Table 4: Fume exhaust system cleaning protocol

Periodic maintenance (six monthly) and performance testing

24. Use the maintenance schedule and performance testing in Table 5 as a guide for minimum requirements. More frequent maintenance may be required where the fume cupboard is in continual use.

Note: Record all results in the fume exhaust system Logbook.

Table 5: Periodic maintenance and performance testing

Annual maintenance

25. Annual maintenance includes periodic maintenance (six-monthly) plus the following.

Table 6: Annual maintenance

Specific inspection, testing and maintenance

Fume scrubber pH maintenance by F&S and engaged contractors

26. Where a scrubber is fitted to neutralise acidic\alkaline emissions, it is important to maintain the active solution pH. Use the following protocol to inspect, test, and maintain fume scrubber pH.

Table 7: Fume scrubber testing and maintenance

Fume scrubber maintenance by F&S or engaged contractors

27. The special filter pads in the fume cupboard scrubber should be inspected at least every 12 months. Use the following protocol. For further details refer to the Safe use of wet scrubbers guideline.

Table 8: Scrubber maintenance

Carbon Filters

28. Inspect activated carbon filters (if fitted) at six-monthly intervals (maximum). In cases of constant high-level use of toxic materials, check the system effluent often for contamination. If there is obvious fume and odour breakthrough, notify F&S to install replacement filters.

Non-conforming equipment

29. Non-conforming fume exhaust systems are those that:

• fail the smoke test (described as Dangerous in the AS 2243.8); and
• cannot achieve a face velocity of at least 0.4 m/s under any usable condition.

30. Any fume exhaust system that does not conform to the specified performance criteria should be tagged or labelled according to danger sign. Before leaving the site the Inspector shall advise the Site Contact of the details of the nonconforming system. WEG should also be notified and if needed advise on any other suitable action.

Summary of results

31. A summary of the fume exhaust system results are made available to the local area and WEG for information.
32. Reported results include:

• face velocity tests, in which the average of the mean velocities from the measurement points are recorded; and
• smoke tests, to which the following interpretation apply:

Table 9

33. Local areas are to keep the following records for their fume exhaust systems:

• initial documentation - Request form and site plan;
• purchase details - System details incorporated in the purchase contract;
• commissioning documentation (in consultation with F&S);
• annual and six monthly testing results;
• logbook; and
• labels.

Reclassifying

34. If the proposed use exceeds its current classification, it is the user's responsibility to upgrade (by a formal request to WEG). An interim measure can include access to a suitable exhaust system. Refer to the Fume exhaust system request form.
35. Where practical, an upgrade of a fume exhaust system may be possible by fitting a cleaning device (filter or scrubber).
36. When the requirements of the fume exhaust system change to a point where the scrubber or cleaning device is no longer needed, approval is sought from the WEG before the cleaning device can be decommissioned or rendered inoperative.
37. Label the modified fume exhaust system according to its new classification.

Decommissioning

38. Where a decommissioned system is not expected to be reactivated in the foreseeable future, the redundant system is removed. This includes the ductwork, fan, scrubber and associated equipment.
39. Any exhaust system that is no longer required is decommissioned or removed by F&S. The logbook is kept by the local area for a period of no less than five years.
40. Any fume exhaust system that cannot be brought to the classification required is reclassified, decommissioned or removed.

Incident reporting

41. All incidents involving the fume exhaust systems at the University are reported via the University's workplace safety incident reporting tool as per the WHS Incident management procedure.

Training obligations/courses

42. WEG provide chemical safety courses and some local WHS Committees have made these courses compulsory for new chemical users. Local inductions cover chemical safety and management requirements. Refer to WHS Training web page.

Logbooks

43. Logbooks:

• inform the user of the fume exhaust system's performance test results and whether the fume cupboard is working satisfactorily;
• inform maintenance personnel about the system's faults and last repair and user's maintenance and checks; and
• provide a record of all maintenance work conducted.

44. A logbook is specific to a particular cupboard. It is located at the fume exhaust system. Information recorded includes:

• commissioning test results;
• annual and six monthly performance testing results, which are supplemented by a test report. See Labels Section;
• repair or other maintenance;
• fault reports;
• scheduled cleaning details;
• wash-down details in perchloric cupboards;
• scrubber conditions or pH;
• scrubber drainage date;
• filter checks; and
• additional comments.

45. All of these entries should include the:

• date; and
• initials or name of the person making the entry.

46. Upon the decommissioning of a fume exhaust system, or the completion and filling of a logbook, the logbook shall be kept by the local area for a period of no less than five years.

Labels

47. There are several labels or signs relevant to or affixed to fume cupboards, including:

• manufacturer labels;
• fume cupboard classification labels (for scrubbed, perchloric and special systems);
• Australian Standard warning label (including spillage containment volume of the fume cupboard); and
• performance test results label.

48. The performance test results label indicates whether the system passes the required tests.
49. A Danger Tag may be affixed to the fume exhaust system. A fume exhaust system under repair is tagged using an "out of service’" and all chemicals and operations in the cupboard are removed. The issuing person is the only person who removes this tag.
50. In the event of a failed performance test, a "out of service" tag is attached. This tag is only removed by an authorised person after due consideration of the fault. Refer to the Isolation and Danger Tagging Procedure.

Sources