When PVC is burned during the lasering process the extremely corrosive, acidic Hydrogen Chloride (HCI) 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.
HCI is classed as a major health hazard, and as a result has a maximum exposure level of 1ppm (Part Per Million) over an eight hour period (from HSE EH40/2000 Occupational Exposure Limits).
Protecting the laser
Not only is HCI 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 in the BOFA ADVANTAGE range have a specially developed two part epoxy for this purpose.
Next we come to filtration. The two 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 HCI that passes through the two stage pre-filter and HEPA filter will be absorbed within a layer of media that is specifically designed to absorb and neutralise the HCI gas.
ADVANTAGE units fitted with the PVC upgrade have an HCI sensor mounted within the exhaust of the system. This unit is specific to HCI and will only be activated when HCI 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 HCI. It is advisable to check with the manufacturer of the extraction system to make sure an HCI sensor is fitted.
AD PVC iQ
The AD PVC iQ extraction system has been designed to effectively deal with the corrosive nature of the fumes generated when laser marking, coding and engraving PVC materials.