BOFA's range of ADVANTAGE laser fume extraction and filtration systems are designed for applications that generate particulate and gaseous volatile organic compounds (VOC's) within the Laser Marking, Coding and Engraving Industries.
When PVC is burned during the lasering process the extremely corrosive, acidic Hydrogen Chloride or HCL is produced. It is imperative that this fume is removed quickly and efficiently for both the safety of the operators and to protect the laser and surrounding equipment.
HCL is classed as a major health hazard, and as a result has a maximum exposure level of 1ppm (Part Per Million) over an 8 hour period. (from HSE EH40/2000 Occupational Exposure Limits).
Not only is HCL a major hazard to health but it is also extremely corrosive. If this acidic fume is allowed to migrate onto the laser lens housing and associated components it will, over a period of time, cause irreversible corrosive damage.
Now we have established the problems that lasing with PVC can cause, we can look at how to extract the fume safely without damage to the extractor.
First of all it is imperative that all internal contact parts are lined in an acid resistant coating. The PVC upgrades available on the BOFA Advantage units have a specially developed 2 part epoxy for this purpose.
Next we come to filtration. The 2 stage pre filters used in the Advantage extractors are completely sealed. This is a very important factor as the fume that enters the pre filter chamber will drop in velocity separating the liquids into the sealed sump. Some extractors have absorbent pads to soak up this liquid. These pads rest directly under the pre filter bags that make it both very difficult and dangerous to handle on filter change.
Any of the HCL that passes through the 2 stage pre filter and HEPA filter will be absorbed within a layer of media that is specifically designed to absorb and neutralise the HCL gas.
Advantage units fitted with the PVC upgrade have an HCL sensor mounted within the exhaust of the system. This unit is specific to HCL and will only be activated when HCL is detected. Many extraction systems are fitted with gas detection sensors but these are normally for VOC (Volatile Organic Compounds) and will not be activated by HCL. It is advisable to check with the manufacturer of the extraction system to make sure an HCL sensor is fitted.
PVC Extraction Unit: