Welding Fumes LEV Testing: Australian Requirements & Best Practice

📋 Part of our complete series: Welding Fumes Assessment Australia: The Complete Guide

Welding Fumes LEV Testing: Australian Requirements & Best Practice

Local Exhaust Ventilation (LEV) is the primary engineering control for welding fumes in Australia. When properly designed, installed, and maintained, LEV can reduce welding fume exposure by 90% or more. However, a poorly designed or inadequately maintained LEV system provides false assurance of safety. Australian standards and the SafeWork Australia Code of Practice require regular testing and examination of LEV systems—yet many welding operations have never conducted a formal LEV test or remain unclear about what a test should verify. This article explains LEV design principles, Australian testing requirements, and how to ensure your LEV system is performing as intended. For more information, see our guide to chemical hazards and workplace exposure standards.

What Is LEV and Why It Matters for Welding Fume Control

Local Exhaust Ventilation (LEV) is a system that captures welding fume at the source—at or near the point where the fume is generated—before it disperses into the breathing zone of the welder. LEV is the preferred control method under the hierarchy of controls and is mandated by Australian WHS standards for any welding operation where exposure cannot be controlled through process substitution (e.g., switching to lower-manganese consumables).

LEV systems comprise several components:

Capture Device: The component positioned closest to the fume source (e.g., fume gun, extraction arm hood, booth).
Ducting: Pipes that transport fume-laden air from the capture device toward the cleaning device and fan.
Air Cleaning Equipment: Filters (bag filters, cartridge filters) or other collectors that remove fume particles from the air before exhaust.
Fan: Typically a centrifugal or axial fan that creates negative pressure and drives air movement through the system.
Exhaust: The point where cleaned air is discharged (usually to atmosphere, sometimes recirculated indoors if cleaning is highly efficient).

The effectiveness of LEV depends on all these components functioning together. A leak in ducting, a clogged filter, or a reduction in fan speed will severely compromise performance.

Types of LEV for Welding Operations

Different welding operations require different LEV configurations:

1. Fume Guns (Suction Guns)
A fume gun is a handheld extraction device that the welder uses while welding. The gun captures fume directly from the arc and draws it into an integral flexible hose connected to the LEV system. Fume guns are ideal for portable welding (e.g., structural steel assembly) where fixed LEV would be impractical. Effectiveness depends on the welder positioning the gun correctly (typically within 150–300 mm of the arc).

2. Extraction Arms
An extraction arm is a flexible or articulated duct positioned above or beside the welding workstation, with a capture hood at the end. The welder maintains the hood position near (but not in the way of) the welding arc. Extraction arms are commonly used in fabrication shops and fixed workstations. They are less portable than fume guns but allow for higher capture velocities and better fume control if positioned correctly. Learn more about welding fumes risk assessment in our detailed guide.

3. Backdraft Hoods (Benchtop Extraction)
A backdraft hood is a partial or full enclosure positioned behind the welder, drawing fume away from the welder’s breathing zone. Backdraft hoods work well for small workpieces but are less effective for large structures. They require careful design to avoid drawing fume across the welder’s face.

4. Booth Extraction (Spray Booths, Welding Booths)
A welding booth is a partial or full enclosure with mechanical ventilation designed to extract fume from all directions. Booths are ideal for high-volume welding operations and provide excellent fume control when designed with appropriate air velocities and exhaust capacity. Booth design must comply with AS 1668.1 for building ventilation. Learn more about stainless steel welding fumes hazards in our detailed guide.

5. Building Ventilation (Dilution Ventilation)
Some facilities rely on general building ventilation (large roof exhaust fans, open doors and windows) to dilute welding fume in the air. This is dilution ventilation, not local exhaust ventilation. While building ventilation may reduce fume levels, it is not considered adequate control for welding fume in Australia unless air monitoring demonstrates that the 1 mg/m³ WES is reliably met. Building ventilation alone is rarely sufficient for high-volume welding.

LEV Design Principles: Capture Velocity, Face Velocity, and Duct Velocity

LEV performance depends on three key design parameters:

Capture Velocity: The minimum air velocity required at the edge of the capture device (hood opening) to capture fume drifting away from the source. For welding fumes, capture velocity at the hood opening should be approximately 0.5–1.0 m/s (metres per second) depending on the type of hood and the nature of the fume source. A wider hood opening requires higher face velocity; a narrowly targeted hood (such as a fume gun) can achieve capture with lower face velocity.

Face Velocity: The air velocity passing through the capture device opening (e.g., the opening of a fume gun or extraction arm hood). For welding fume extraction:

Fume guns: face velocity should be 15–25 m/s.
Extraction arms: face velocity should be 10–15 m/s.
Backdraft hoods: face velocity should be 0.5–1.0 m/s (lower velocities to avoid turbulence).
Booths: face velocity should be 0.5–0.75 m/s across the opening.

Duct Velocity: The air velocity inside the main ducts carrying fume-laden air toward the filter. For welding fume systems, duct velocity should be at least 10–15 m/s to prevent fume particles from settling in the ducting and causing blockages or accumulation of combustible dust.

These design principles are outlined in the SafeWork Australia Code of Practice: Welding Processes 2021 and in technical standards such as AS 1668.1 (Ventilation Systems) and relevant industrial hygiene guidance.

Australian Standards and LEV Testing Requirements

AS 1668.1-2015: The Ventilation Standard
AS 1668.1 is the Australian Standard for ventilation systems and applies to all LEV systems, including welding fume extraction. The standard specifies design, installation, testing, and maintenance requirements. Key provisions relevant to welding LEV include:

LEV systems must be tested to verify compliance with design specifications before being brought into service (commissioning test).
Annual examination and testing are required to ensure continued performance (maintenance testing).
Where an LEV system is found to be deficient, the system must be reported to the PCBU and remedial action must be documented.
Records of all tests and maintenance must be retained.

SafeWork Australia Code of Practice: Welding Processes 2021
The Code of Practice specifies that LEV systems for welding must be:

Designed and commissioned by a competent person (e.g., certified occupational hygienist, competent engineer).
Examined and tested annually.
Maintained in good working order (filters cleaned or replaced, fan operation checked).
Subject to air flow testing to verify capture and duct velocities.

WHS Regulations Schedule 2, Part 3.1: PCBU Obligations for Welding
The Regulations require PCBUs to ensure that LEV systems are:

Installed in accordance with manufacturers’ specifications and design standards.
Tested and certified as compliant before use.
Examined and tested regularly (at least annually).
Maintained in effective working condition.

What LEV Testing Involves: The Annual Examination

A formal LEV test (or examination and test) for a welding fume extraction system typically includes the following:

1. Visual Inspection
The technician visually inspects all components:

Capture device: Check for damage, blockages, or deterioration. For fume guns, check for cracks in the hood or damage to the nozzle.
Ducting: Inspect for corrosion, holes, leaks, loose connections, or internal accumulation of fume particles.
Fan: Check for corrosion, unusual noise, vibration, or signs of wear.
Filter: Check for visible dirt, moisture, or damage; measure filter pressure drop if a gauge is installed.
Electrical connections and safety switches: Verify integrity of all electrical components.

2. Air Flow Measurement
The technician measures air velocities at key points in the system:

Face Velocity: Measured at the capture device opening using a vane anemometer. Multiple measurements are taken across the opening to calculate average face velocity. Results are compared to design specifications.
Duct Velocity: Measured in the main duct using an anemometer or pitot tube. Results verify that velocity is maintained above minimum thresholds (typically 10–15 m/s for welding systems).
Capture Velocity: For some systems, measured at a distance from the hood opening (e.g., 150 mm) to verify effective capture of fume.

3. Static Pressure Testing
The technician measures static pressure at various points (hood, upstream of filter, downstream of fan) to diagnose system resistance and identify blockages or leaks.

4. Filter Condition Assessment
The filter is inspected for:

Visual dirt load (colour of the filter surface).
Pressure drop across the filter (if a gauge is installed; typical threshold is 500 Pa or 50 mm water gauge—filters should be changed before this is reached).
Cracks, holes, or deterioration.
Proper seating and gasket integrity (to prevent bypass).

5. Documentation and Reporting
The technician documents all measurements and observations in a test report. The report includes:

System description (type of LEV, location, age, maintenance history).
Design specifications (expected face velocity, duct velocity, capture velocity).
Actual measured values.
Assessment of compliance: “Pass” (meets specifications), “Pass with observations” (minor issues that should be monitored), or “Fail” (one or more parameters outside specification; remedial action required).
Recommendations for maintenance, repair, or upgrades.
Date of next examination.

Common LEV Deficiencies Found During Testing

Experience shows that many welding LEV systems have deficiencies when tested. Common issues include:

1. Reduced Face Velocity Due to Clogged Filters
Filters accumulate fume particles over time. As the filter clogs, system resistance increases and fan flow rate decreases, resulting in lower face velocity at the capture device. This is the most common deficiency. Solution: establish a planned filter replacement schedule (e.g., every 6 months or annually, depending on welding volume) rather than waiting for a visual indication of dirt.

2. Ducting Leaks or Disconnections
Ducting can corrode, develop holes, or become disconnected at joints, allowing unfiltered air to escape and reducing negative pressure at the capture device. Solution: inspect ducting annually, seal leaks with appropriate duct tape or sealant, and secure all connections with clamps or tape.

3. Fan Speed Reduced
Some facilities reduce fan speed (via a damper or VFD drive) during periods of low activity, intending to save energy. However, if fan speed is reduced below design specifications, capture velocity drops and exposure control is compromised. Solution: maintain fan speed at design specification during all working hours when LEV is in use.

4. Capture Device Not Positioned Correctly
For extraction arms and fume guns, effectiveness depends on correct positioning by the welder. Some welders position the hood too far from the arc or at an angle that reduces capture. Solution: provide training and supervision, and consider using articulated arms that are easy for welders to reposition quickly.

5. Multiple Capture Devices on a Single System
Some facilities connect multiple fume guns or extraction arms to a single LEV system. If multiple capture devices are used simultaneously, the system may not have sufficient flow to maintain design velocity at all devices. Solution: install a multi-station LEV system designed for simultaneous use of multiple capture devices, or use a priority system (dampers that divert flow to the active capture device).

6. Inadequate Filter Capacity
Some facilities install LEV systems with undersized filters, resulting in rapid clogging and high pressure drop. Solution: ensure filter area is adequate for the system airflow. As a rule of thumb, filter face velocity (air velocity through the filter medium) should not exceed 1.5–2.0 m/min.

LEV Performance for Different Welding Materials: Stainless Steel vs. Mild Steel

The fume composition varies depending on the base material and consumable used, which can affect LEV design and testing:

Mild Steel Welding: Fume from mild steel welding is primarily iron oxides and manganese. Fume particles are relatively coarse and tend to settle in horizontal ducts relatively quickly. Duct velocity should be at least 10 m/s to prevent settling. Filters can be standard bag filters or cartridge filters.

Stainless Steel Welding: Fume from stainless steel welding contains chromium (including hexavalent chromium, Cr(VI)), nickel, and iron oxides. Stainless steel fume particles are finer and more likely to remain suspended; they are also more irritant to the respiratory system. Duct velocity should be at least 15 m/s. Filters must be capable of collecting fine particles; HEPA or ultrafine filters may be required to meet air discharge standards. Some jurisdictions regulate the discharge of Cr(VI) to atmosphere and may require special handling of contaminated filters.

Aluminium Welding: Fume from aluminium welding is lighter and may behave differently in LEV systems. Duct velocity should be at least 12–15 m/s.

LEV testing should account for the specific materials being welded and verify that the system is designed appropriately.

Maintaining LEV Performance: A Practical Schedule

LEV performance deteriorates over time without maintenance. A practical maintenance schedule for welding LEV includes:

Maintenance Task	Frequency	Owner
Visual inspection of capture device and ducts	Weekly/Monthly	Welder/Supervisor
Check fan for unusual noise or vibration	Monthly	Supervisor/Maintenance
Clean or replace filter (or measure pressure drop if gauge installed)	6 months or as indicated	Maintenance technician
Formal LEV examination and testing (air flow measurement, documentation)	Annually	Competent external technician (e.g., certified occupational hygienist)
Review test report and implement recommendations	Within 30 days of testing	PCBU/HSE Manager
Fan bearing lubrication, belt tension, electrical safety inspection	Annually	Maintenance technician

When to Upgrade or Replace LEV Systems

Some welding operations use older LEV systems that are difficult to maintain or increasingly fail testing. Upgrade or replacement should be considered if:

The system consistently fails to meet design specifications (face velocity, duct velocity) even after filter replacement and maintenance.
Fan is aging (typically > 15–20 years) and replacement parts are difficult to source.
System cannot be adapted to new welding processes or materials (e.g., switching from mild steel to stainless steel welding).
Air monitoring shows that welding fume exposure remains above the WES despite the LEV system being in place, suggesting inadequate control.
Ducting is severely corroded or has multiple leaks that cannot be cost-effectively sealed.

New LEV systems should be designed and installed by a competent occupational hygienist or engineering firm experienced in welding fume control. Commissioning testing must be conducted to verify that the new system meets design specifications before it is placed in service.

Frequently Asked Questions

Q1: How much does LEV testing cost, and is it worth the investment?
A: Formal LEV testing by a competent technician (e.g., certified occupational hygienist) typically costs $800–$2,500 per system depending on system complexity and location. This is a worthwhile investment because it verifies that controls are working as intended and protects the PCBU from regulatory liability. If testing reveals deficiencies, the remedial cost is usually modest compared to the cost of a regulatory breach or workers compensation claim for occupational disease.

Q2: Can an untrained person conduct LEV testing?
A: No. LEV testing requires calibrated measurement equipment (anemometer, pitot tube, manometer) and technical knowledge to interpret results. Testing should be conducted by a person with qualification in occupational hygiene (e.g., Certified Occupational Hygienist, AIOH-accredited practitioner, or engineer with LEV testing experience). Some regions require the technician to be NATA-accredited or hold specific qualifications.

Q3: What happens if an LEV system fails testing?
A: If testing shows that face velocity or duct velocity is below specification, the PCBU must take action to remedy the deficiency. Common remedies include filter replacement, sealing of ducting leaks, fan speed adjustment, or repair of capture device. If the system cannot be brought into compliance, the welding operation should not proceed until controls are adequate, or air monitoring should be conducted to confirm that the WES is met despite the LEV deficiency. A Prohibition Notice may be issued by the regulator if the PCBU continues welding with non-compliant LEV.

Q4: Is annual testing sufficient, or should it be more frequent?
A: Annual testing is the minimum requirement under AS 1668.1 and the Code of Practice. However, if welding volume is very high or if the operation is in a harsh environment (coastal location with salt spray, high ambient dust), more frequent testing (e.g., 6-monthly) may be prudent. Additionally, after any major repair, filter replacement, or system modification, a post-maintenance test should be conducted to verify that the system still meets specifications.

Q5: Can LEV testing be conducted in-house by the PCBU’s maintenance team?
A: Not as a substitute for external professional testing. While the maintenance team can conduct routine visual inspections, cleaning, and filter replacement, the formal examination and testing (air flow measurement, pressure testing, documentation) must be conducted by a competent external technician. This ensures independence, proper equipment calibration, and regulatory acceptability of the test results.

Q6: What should be done with the LEV test report?
A: The test report should be reviewed promptly by the PCBU’s HSE team. Any recommendations should be implemented within a defined timeframe (e.g., 30 days). The report should be retained with other compliance records for regulatory inspection. A summary of test results and any action taken should be communicated to workers (via toolbox talk, notice board, or email) to demonstrate that controls are being monitored and maintained.

Moving Forward: Ensuring LEV Performance

LEV is the foundation of welding fume control in Australian workplaces. Regular testing and maintenance ensure that LEV systems perform as designed and protect workers from exposure. {{LINK_CONTACT}}Contact our team{{/LINK_CONTACT}} to arrange professional LEV testing and design services for your welding operation.

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