Differences

This shows you the differences between two versions of the page.

--- tool:laserfilter [2019/04/02 05:24] – adam_tuck
+++ tool:laserfilter [2021/05/05 15:55] (current) – johnc
@@ Line 1: / Line 1: @@
 ====== 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) 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://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.
 Many commercial systems exist in order to address these concerns, and in general follow the same design principles:
   - Utilize sufficient air flow to clear the space, while keeping the filter and laser under negative pressure.
-  - Have a staged filer setup to remove various substances consisting of:
+  - Have a staged filter setup to remove various substances consisting of:
-       - a)Pre-filtration - remove large particles using a larger bag filter, washable medium, or cheap pre-filter.
+       - Pre-filtration - remove large particles using a larger bag filter, washable medium, or cheap pre-filter.
-       - b) Small Particle Filtration - HEPA filters or equivalent can be used to remove the majority of smaller particles generated by the laser/material.
+       - Small Particle Filtration - HEPA filters or equivalent can be used to remove the majority of smaller particles generated by the laser/material.
-       - c) VOC Removal - Although various methods for VOC removal exist, the most common is utilizing an activated carbon bed to remove any final VOCs
+       - VOC Removal - Although various methods for VOC removal exist, the most common is utilizing an activated carbon bed to remove any final VOCs
-       - d) Post Filter (Optional) - If concerns regarding the expulsion of carbon dust from the bed exist, such as a re circulation application,
+       - Post Filter (Optional) - If concerns regarding the expulsion of carbon dust from the bed exist, such as a re circulation application,
   - Use of sensors/monitoring to determine service intervals/efficacy.
@@ Line 15: / Line 15: @@
 ===== Air Flow Requirements =====
 For an 80W CO2 laser such as that of VHS, the suggested minimum flow rate is 250cfm. In order to meet these requirements, a target setpoint of 350cfm was used. To meet this spec, two axial fans original designed for hydroponic applications were investigated. The fan curves are below:
-{{:tool:vhs_fan_specs.png?direct&400|}}
+{{:tool:vhs_fan_specs.png?direct&650|}}
-{{:tool:vhs_laser_fan_curve.png?direct&400|}}
+{{:tool:vhs_laser_fan_curve.png?direct&650|}}
 Given the 6' ducting, and required filters, the major and minor Dp's were calculated and compared to the available fan curves. This determined that the optimum setup was a single M6 fan with minimal other backpressure as seen below:
-{{:tool:vhs_piping_design.png?direct&400|}}
+{{:tool:vhs_piping_design.png?direct&500|}}
 ===== Filter Setup =====
@@ Line 30: / Line 30: @@
 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) 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 full filter area, the residence time in the current design is approximately 0.6s.
+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.
+The current filter setup is shown below:
+{{:tool:vhs_filterbox.jpg?direct&400|}}
+(Replace with updated and rotated photo)
 ===== Filter Maintenance =====
@@ Line 46: / Line 51: @@
 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 and take the laser offline for further use.
+===== List of Past Maintenance Logs =====
+  * [[tool:laser_cutter:maintenance_logs:2016_03_23|March 23, 2016]]
+  * [[tool:laser_cutter:maintenance_logs:2017_01_22|January 22, 2017]]
+  * [[tool:laser_cutter:maintenance_logs:2017_02_27|February 27, 2017]]
+  * [[tool:laser_cutter:maintenance_logs:2017_03_21|March 21, 2017]]
+  * [[tool:laser_cutter:maintenance_logs:2017_05_27|May 27, 2017]]
+  * [[tool:laser_cutter:maintenance_logs:2018_01_05|Jan 5, 2018]]
+  * [[tool:laser_cutter:maintenance_logs:2018_02_06|Feb 6, 2018]]
+  * [[tool:laser_cutter:maintenance_logs:2018_05_05|May 5, 2018]]
+  * [[https://talk.vanhack.ca/t/laser-maintenance-party-sun-sep-2nd-1pm-5pm/8246/12|Sep 2, 2018]]
+  * [[https://talk.vanhack.ca/t/oct-12-2018-laser-cutter-is-out-of-order/8387/3?u=lukecyca|Oct 14, 2018]]
+  * [[https://talk.vanhack.ca/t/laser-cutter-out-of-order-02-05-2021/11867/10|May 4,2021]]
+  *
 [[tool:redsail_cm1080_laser_cutter|Back to the laser cutter]]