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Thread: Ventilation HELP!!!!

  1. #16
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    Quote Originally Posted by Kasey Maxwell View Post
    its only a 3/4hp fan, i can use it up to 8 hours a day here and there, the heat bill is the same because I don't heat this room, it stays cool and I close the door when I'm using the fan. If im going to be working in there I open the heat vent and let it warm up then close it before I start, with the door closed I don't get much if any heat loss from the house, just the room.
    So, either that room doesn't get down to -20, which means you're pulling heat from the rest of the building (likely), or you're running your laser in -20 degree weather (unlikely). If it's neither of those, you have near zero airflow in your exhaust.
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  2. #17
    Quote Originally Posted by Dan Hintz View Post
    So, either that room doesn't get down to -20, which means you're pulling heat from the rest of the building (likely), or you're running your laser in -20 degree weather (unlikely). If it's neither of those, you have near zero airflow in your exhaust.


    That is what I am thinking. I am nowhere near the 500 cfm that is required for my machine and when it gets down to zero I can not keep my building above 55 degrees (the lowest setting on my thermostat)
    Universal M-300 (35 Watt CO2)
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  3. #18
    Quote Originally Posted by Jared Gaylord View Post
    Okay Guys so this is my first post on this forum so excuse the Newbie here, Anyways.

    I am looking into getting my first laser system (Epilog Zing 16) for a starting out home business laser and i do live in Alaska, So i have a problem with the venting.
    In the summertime i am fine with venting to the outside from my room through just cracking the window and running my 4" Hose outside to my fan but i am trying to figure out what i can do in the winter time without letting all the heat out!! I do rent the house with my wife and another couple so i am not about to ask my landlord if i can drill a 4.25" hole in his wall, so my question to you guys\girls is how the heck can i work in the winter (7 Months) without lettin all the heat out into the -30F/-40F weather and also if you have any pointers on the a specific fan that would be awesome its going to require a minimum of 400cfm at 6" static pressure Thanks a bunch folks!!!!
    If you really need 400 cfm at 6 inches of static, you might as well just leave the hose hanging out the open window. Without some sort of make-up air, the house will go into negative pressure and 400 cfm will be doing its darnest to leak back into the house. If the house is well sealed, you may hear the toilet and sink drain traps gurgle as air sucks in through the vents, or you may (or may not) notice the carbon monoxide from the oil, gas, or fireplace chimneys pouring back down into the house (the buoyancy of warm flue gases doesn't have a chance again a 6 inch static fan) or you will find it impossible to either close or open doors (6 inches of water gauge is about 31 pounds per square foot times a 21 square foot door).
    If you are running a high static fan in the house, you need a make-up air source.
    Six inches of static is more normally seen in dust collection systems when high velocity is needed to keep particulate moving. Six inches of static will push about 400 cfm 75 equivalent feet through 4" duct. Cut the length in half and the pressure requirements will also halve. Cut the airflow in half and the pressure needed drops by a factor of four.

    400 cfm x 100 degrees temp differential x 1.08 conversion factor equals 43200 BTUs of heat loss per hour. That's about a half gallon of propane at $3 ? per gallon or $1.50 per hour. Its also about 13 KW of electricity at $0.10 ?/per KW or $1.30 per hour. Natural gas at a buck per therm will be close to $0.50/hour.
    If you can cut back to 200 cfm and use only use the laser when its above 20F, then divide these costs by 4. Realistically, the cost of ventilation should be about $0.50/hour.

    Hope this helps,

  4. funny.........its been working just fine for 2 years like this.........you'd think if there was zero circulation then the room would fill with smoke, that has never happened. The only other option would be to get one of those over priced giant filter systems and keep it in that instead of going to the outside, just a thought.......
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  5. #20
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    Alaska

    Hey there Kasey if you dont mind me asking whereabouts in Alaska do you live and is it the 16 or 24 that you own? Thanks----Jared

    Quote Originally Posted by Kasey Maxwell View Post
    funny.........its been working just fine for 2 years like this.........you'd think if there was zero circulation then the room would fill with smoke, that has never happened. The only other option would be to get one of those over priced giant filter systems and keep it in that instead of going to the outside, just a thought.......

  6. #21
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    Quote Originally Posted by Kasey Maxwell View Post
    funny.........its been working just fine for 2 years like this.........you'd think if there was zero circulation then the room would fill with smoke, that has never happened. The only other option would be to get one of those over priced giant filter systems and keep it in that instead of going to the outside, just a thought.......
    We didn't say zero ventilation... what we said was you're stealing heated air from the rest of the building and throwing it outside. And likely at a rate much lower than it could be...
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  7. #22
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    Unless your house is super insulated try this the next time you are running the laser. Go to all you wall outlets and put your hand on it. you will most likely feel the cool to cold air coming in. same thing with any entry door, garage (if attached). Whatever you are blowing out will have to come from somewhere. Dennis put it more technical terms above. THE ONLY way to have zero loss of heat is with an indoor carbon filter system. Put a thermometer at the end of your vent pipe outside and you will see for yourself. Look at the temp before you turn on the fan and then after you have been running it for an hour or so.

    Hope this helps and ...
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  8. #23
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    Nice calculations Dennis!
    George
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  9. #24
    Quote Originally Posted by George Brown View Post
    Nice calculations Dennis!
    Hello George,
    I have decades of doing calculations, some of it in industrial ventilation.
    Just wanted to show that proper ventilation, even in Alaska, is not all that expensive.

    Over the years, I have designed all sorts of vent systems for printing plants and laser engraving shops. I am always amazed at how little thought the manufacturers of laser equipment put into their designs when it comes to ventilation. Maybe things have changed recently (I'm retired), but most of the lasers that I have seen just give one an undersized hole on the back of the machine to where one can hook an over sized sucker. When it works poorly, the owner is told to buy a bigger sucker.

    For ventilation to work well, the machine needs a river of air to flow through the machine carrying the pollutants downstream and away. If properly channeled, the flow does not have to be much, about 100 feet/minute. A cross sectional area of most lasers is only 2 or three square feet looking at the narrow end. A 2 square foot cross should then need about 2 cfm. The laser should have a suction grill at one end, the air should pull gently and uniformly across the work and the polluted air should be removed at the other end. Call this the river of air method of ventilation.

    Most lasers that I have seen have been built with no provisions at all for air intake. The air comes in through holes in the bottom or cracks around the lid and pulled out through a discharge in the middle of the longer dimension, usually in the back. High static fans are required as this is a mighty inefficient method of producing airflow. 400 cfm of airflow though a laser would blow the acrylic right off the honeycomb if one really had 400 cfm of air. The design isn't right.

    Fill your bathtub up with water and add a table spoon of ink. Then open the drain and turn the water on enough so that water in equals water out. You will use lots of water and it will stay blue forever. Call this the bathtub method of ventilation.
    This is the way most lasers are designed.

    I can understand ventilation being overlooked in inexpensive Chinese lasers like mine, but $35,000 American lasers are just as bad (my apologizes if this has been changed recently). If manufacturers took the ventilation issue to heart and spent a few hours with an airflow engineer, a whole lot of noisy overpowered fans could be eliminated.

    Dennis

  10. #25
    Dennis,

    I can't say about any other brand but Universal's have the air intake designed quite well (mine are 10 years old) the air come in the bottom of the front door, up through the hollow door where it is directed into the body of the laser at and above the focal point of the laser the exhaust is at the same height on the back of the machine, which causes most of the airflow to be at the level where the smoke is created. It is just that the way the intake is designed that it is hard to find, when the front door is open you can't really see it because half of it is in the door and the other half is in the top of the machine. Although I will agree with you that the holes in the back to connect the exhaust to are a bit small for the amount of air they say you should be pulling through it.
    Universal M-300 (35 Watt CO2)
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  11. #26
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    Question for Dan Hintz.....

    Am new for the site, just bought a used Epilog 24, 35watt laser. Will be using it in my small office, just talked to the landlord and he will not let me drill a hole thru the brick wall to vent it out. Soooo..... looks like I will be building a Filtration System !

    Question: The bottom filter.... a basic furnace filter and a charcoal filter ( blue scrubber I assume is the furnace filter ). You have all this combined in to one filter and then the actived charcoal above it. Is the charcoal filter needed ? or would a pleated furnace filter be adaquate ?

    I do wood working and plan on building my own box to fit my needs, was thinking about putting a sealed door on the front to access the filter area below to clean and replace the filter. Also have a lid on it to access the charcoal and hepa filter above. My wife works for a HVAC comp. so have access to filters and may have then build me a metal cabinet instead of my wood one.

    This site is very helpfull, the $2000 filtration system is not in my budget for just starting out.

    Thanks, would appricate your help....... and any others that want to jump in with info.
    Last edited by Todd Koopman; 03-07-2012 at 12:39 PM.

  12. #27
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    Todd,

    See my thread on building your own system for <$200 (not $2,000). The carbon is there to filter out vapor-based particulate matter, stuff you don't want in your lungs... like smoke from cutting wood or acrylic. If you're not working with materials that break down on a molecular level when heated, you don't need the carbon... Marble or other stone processing is one such example, as they just bleach the color or "chip out" the stone.
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  13. #28
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    Quote Originally Posted by Dan Hintz View Post
    Todd,

    See my thread on building your own system for <$200 (not $2,000). The carbon is there to filter out vapor-based particulate matter, stuff you don't want in your lungs... like smoke from cutting wood or acrylic. If you're not working with materials that break down on a molecular level when heated, you don't need the carbon... Marble or other stone processing is one such example, as they just bleach the color or "chip out" the stone.
    Thanks Dan..........plan on doing mainly Wood, Acrylic, with some tile, marble and some leather. Just figured the activated carbon would be enough with out the carbon filter, but sounds like you guys have it figured out, so will not alter a good design.

    Thanks again........ Todd

  14. #29
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    Quote Originally Posted by Todd Koopman View Post
    Just figured the activated carbon would be enough with out the carbon filter, but sounds like you guys have it figured out, so will not alter a good design.
    Ah, okay, I see what you're saying... I forgot the furnace filter I picked up from Home Depot had an activated charcoal layer on it. Yeah, the thin layer of carbon on the pre-made filter is all but useless for what we're using it for (bulk collection of large material, like stone dust, to prevent contamination of the thick activated carbon bedding), so consider it like it was never there in the first place.
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