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wiki:tools:laserfilter [2025/08/18 20:57] – created - external edit 127.0.0.1wiki:tools:laserfilter [2026/02/28 18:51] (current) – Updated filter spec ddq
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 ====== Laser Filtration System ====== ====== Laser Filtration System ======
-It is well understood that depending on the material being "lased" that the fumes from a laser cutter can be detrimental to human health, either through the release of particulates, or volatile organic compounds (VOCs). (reference: [[https://seas.yale.edu/sites/default/files/imce/other/ISAM%20Makerspace%20Emerging%20Safety%20Items.pdf|Download PDF]]) In particular, wood creates a significant amount of small particulate matter, while most plastics create various VOCs that must be removed from the exhaust stream before it is ducted either inside or outside the space.+It is well understood that depending on the material being "lased" that the fumes from a laser cutter can be detrimental to human health, either through the release of particulates, or volatile organic compounds (VOCs) (reference: [[https://web.archive.org/web/20250405083356/https://assets.pubpub.org/11oas02j/22%20Herrick%20Klein%20Emerging%20Health%20and%20Safety%20Issues%20in%20Makerspaces-31691084105595.pdf|Download PDF]]). In particular, wood creates a significant amount of small particulate matter, while most plastics create various VOCs that must be removed from the exhaust stream before it is ducted either inside or outside the space.
  
 Many commercial systems exist in order to address these concerns, and in general follow the same design principles: Many commercial systems exist in order to address these concerns, and in general follow the same design principles:
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 ===== Filter Setup ===== ===== Filter Setup =====
-In most cases, a prefilter, bagfilter, HEPA filter is the preferred option. This provides the longest lasting filter media for this application of the systems reviewed. However VHS has a modular setup that is arranged to accept standard 20"x25" furnace filters. Therefore the arrangement above was created using: +The VHS laser filter system is designed to use standard 20" x 25" furnace filters in two identical parallel stacks (see photo below). Each stack comprises, from bottom to top: 
-  - 2x reusable/washable plastic prefilters to capture large particles entrained in the flow from the laster +  - Bottom plenum (i.e., empty space); coarse particulates get deposited here 
-  - 4x Filtrete 1900 MPR 1900 "Maximum Allergen Filtrete Furnace Filters" (Can be replaced by a single deep pleat MERV 14 or higher commercial filter as necessary). +  - MERV 6 / MPR300 Pre-filter (x3 layers) 
-  - 6x trays of 1" Jacobi Ecosorb GXB Activated Carbon (or equivilant)+  - MERV8 / MPR 600 Furnace filters (one 2" layer or two 1" layers) 
 +  - MERV11 / MPR 1000 Furnace filters (one 2" layer or two 1" layers) 
 +  - MERV13 / MPR 1900 Furnace filters (one 2" layer or two 1" layers) 
 +  - Jacobi Ecosorb GXB or equivalent granular activated carbon, 4mm or 5 mm particle size (x3 layers) 
 + 
 +{{ :wiki:tools:laser_filter_stack.jpg?direct&400 |}}
  
 This system is designed to: a) reduce particulate entrapment in the fine particulate phase, b) ensure removal of particulate matter which is roughly similar to tobacco smoke as per literature on laser exhaust, and c) have sufficient residence time of the air in the carbon bed, while not increasing the overall dP of the filter system. This system is designed to: a) reduce particulate entrapment in the fine particulate phase, b) ensure removal of particulate matter which is roughly similar to tobacco smoke as per literature on laser exhaust, and c) have sufficient residence time of the air in the carbon bed, while not increasing the overall dP of the filter system.
  
-According to literature from the EPA ([[https://www3.epa.gov/ttn/ecas/docs/cs3-1ch1.pdf|Download PDF]]) it is suggested to use a minimum bed depth of 3", along with face velocities of between 50-100 fpm to reduce streaming and breakthrough, while providing sufficient residence time. It should be noted that in this setup, the number of trays and flow area has been maximized in order to lower dP, and increase residence time. At the specified 350 cfm, and the 1/2 filter box area currently in use, the residence time in the current design is approximately 0.3s. +According to literature from the EPA ([[https://web.archive.org/web/20240617062356/https://www3.epa.gov/ttn/ecas/docs/cs3-1ch1.pdf|Download PDF]]) it is suggested to use a minimum bed depth of 3", along with face velocities of between 50-100 fpm to reduce streaming and breakthrough, while providing sufficient residence time. It should be noted that in this setup, the number of trays and flow area has been maximized in order to lower dP, and increase residence time. At the specified 350 cfm, and the 1/2 filter box area currently in use, the residence time in the current design is approximately 0.3s.
- +
-The current filter setup is shown below: +
- +
-{{:tool:vhs_filterbox.jpg?direct&400|}} +
-(Replace with updated and rotated photo)+
  
 ===== Filter Maintenance ===== ===== Filter Maintenance =====
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 While there are no specific change intervals, once a filter becomes clogged with debris it should be replaced. Current experience is that the filter media shouldn’t need to be replaced any more frequently than once every 3-6 months, but this will be highly dependent on usage. While there are no specific change intervals, once a filter becomes clogged with debris it should be replaced. Current experience is that the filter media shouldn’t need to be replaced any more frequently than once every 3-6 months, but this will be highly dependent on usage.
 In each set of filters, it is recommended to replace the lower filter first, and add the new filter to the top of the stack. In each set of filters, it is recommended to replace the lower filter first, and add the new filter to the top of the stack.
-Repeat for each bank of MERV 8, 10 & 13 filters.+Repeat for each bank of MERV 8, 11 & 13 filters.
 Activated carbon trays (top three) are not a part of this basic maintenance procedure and can be left alone. Activated carbon trays (top three) are not a part of this basic maintenance procedure and can be left alone.
  
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   - No particulate breakthrough   - No particulate breakthrough
  
-At any time if there is a concern over filter operation or maintenance, please call the space at (778) 330-1234, or contact any member of the LCC on #laser on slack and take the laser offline for further use. +At any time if there is a concern over filter operation or maintenance, please contact any member of the LCC via #laser on Slack.
- +
-===== Other References ===== +
-**Note:** The Google Doc linked below contains additional maintenance information, but conflicts with some of the information on this page. As of April 2025, the LCC is working to reconcile these two sources into one definitive reference.  +
- +
-https://docs.google.com/document/d/1_UN9pxrlWqTYGtY5TYYHc2xuRvDM5CxSscJ_hM80spY/edit?usp=sharing+
  
 ===== List of Past Maintenance Logs ===== ===== List of Past Maintenance Logs =====