THE COMPLETE GUIDE TO WELDING
FUME EXTRACTION SYSTEMS:

System Set-up and Validation
System integrity is essential to ensure that the dust collection system is performing as expected. No matter what type of air filtration system you are using, proper setup, commissioning, and system validation will be required. This includes:

• Proper design of the system, including sizing and placement of the collectors, hood and ductwork design for source capture solutions, and analysis of airflow patterns for ambient systems.
• Setup of the filtration device(s) (e.g., dust collector or wet scrubber) according to manufacturer’s specifications.
• Calibration of the system (airflow velocities, etc.) to meet capture rate requirements. 
• Validation and testing to ensure that expected capture rates have been met and resulting air quality meets requirements.  

Always follow the manufacturer's instructions for your dust collector when installing or replacing filters, and use filters that are designed to the specification of the manufacturer. Using improperly fitting filters or improper installation of filters may result in leaks of contaminants past the filter cabinet, which may put the facility out of compliance.

What kind of spark control is recommended for weld fume extraction?
If welding takes place near the system intake or ductwork, it is advisable to have a method of spark arrestance to prevent a stray spark from igniting the filters. A spark arrestance system is recommended to keep sparks out of the dust collector intake. There are several types of spark arrestors available, including metal mesh screening, centrifugal spark arrestors, and detect-and-suppress systems. A centrifugal spark arrestor, which uses centrifugal force to strip the thermal envelope from sparks, is often recommended for heavy spark-producing applications such as welding. The spark arrestors may be installed inline with the ductwork or at the intake for the dust collection system. Learn more: Spark Control Options for Dust Collection.

What is a dust collector filter pulsing system?
A dust collector filter pulsing system is a mechanism used to clean the filters in a dust collector. The system uses compressed air to forcefully pulse the filter media, causing the collected dust and debris to fall into a collection bin or hopper. This process is typically automated and can be timed to occur at regular intervals or based on the pressure drop across the filter. Pulsing the filters in this way helps to maintain their efficiency and prolongs their service life. A coated filter media may enable more efficient filter pulsing.

What kind of fire and explosion safety systems are required for dust collectors for weld fumes?
The dust collector should be equipped with safety systems to ensure continued safe operation and protection from dust collector fires and explosions. The specific requirements are determined by OSHA regulations and standards set by the National Fire Protection Association (NFPA). When collecting combustible dust, the dust collector must conform to system design standards outlined in NFPA 652, NFPA 68 and NFPA 69. (Read more: Are Weld Fumes Combustible?) The exact requirements will depend on the characteristics of your weld fume and the specific hazards in your facility, but may include some or all of the following. 

• Particulate monitor: The dust collector should be equipped with a particulate monitor to detect leaks past the filter chamber. An auto-stop function should shut down the system if a leak is detected. 
• Fire/smoke detector: The dust collector should have a fire/smoke detector that will sound an alarm if a fire is detected in the filter chamber. For maximum safety, the detection system may also be connected to a damper system that shuts off airflow and/or a fire suppression system. 
• Fire suppression system: The fire suppression system may consist of a water sprinkler system, a carbon dioxide (CO2) system, or a clean-agent gas fire suppression system.
• Deflagration system: If your dust is combustible, the dust collector may need to be equipped with explosion vents and a deflagration system in accordance with NFPA 68 and 69.

What kind of preventive maintenance is required for dust collectors?
Preventive maintenance is essential to ensure proper continued working of the dust collection system. Maintenance activities and schedules will depend on the type of dust collector you have and the volume of fume you are collecting. For a cartridge-style dust collector, standard maintenance activities include: 

• Drum/bin emptying: In a cartridge collector, collected dry particulate falls off the filters and into a tray or bin for collection. When the tray or bin becomes full, it must be safely emptied, and dust must be disposed of in accordance with local regulations.  
• Cartridge filter changes: Filters should be changed on a schedule recommended by the manufacturer or when pressure drop across the filter chamber raises by a certain level (specific to your dust collector), indicating that filters have become loaded. 
• Spark arrestor cleaning: Mesh-style spark arrestors must be cleaned frequently to avoid buildup of soot from weld fume. Centrifugal spark arrestors should also be cleaned and inspected periodically to remove dust collected in the dust trap or any buildup on the interior walls. 
• Filter pulsing system: Check the pulsing system on a regular basis to ensure that it is operational and the compressed air valves have not become clogged. 
• Ductwork: Ductwork should be inspected and cleaned on a regular basis to prevent buildup of potentially flammable particulate inside the ductwork.
• General inspection and repair: Regular PM should include inspection of all parts (fans, belts, motor, etc.) to ensure proper operation, and worn or damaged parts should be replaced.

How is weld fume dust disposed of after collection?
Check with local, state, and federal regulations for guidelines on disposing of loaded filter media and collected dust from welding operations, especially if the dust contains toxic byproducts of welding such as chromium, lead or manganese. Safety precautions should be taken by employees when handling dirty filters or emptying dust bins.

• Care should be taken to avoid creating dust clouds when emptying bins for disposal. A vacuum system should be used to clean up any spilled dust. 
• Employees should be provided with personal protection equipment (PPE), including gloves, protective eyewear and N95 masks to avoid breathing in or directly touching dust during filter changes and bin emptying.

For more information on weld fume extraction system design, talk to a RoboVent clean air expert.