Problem With Homemade Cold Smoke Generator

Discussion in 'Info and Practices' started by lowkey, Mar 7, 2016.

  1. lowkey

    lowkey Newbie

    I have built a slightly modified version of this cold smoke generator:

    I have found that I cannot sustain a burn/smolder in this generator and am in need of some suggestions.  I am using a brand new, 1 gallon paint can.  I have made a venturi from a 12" piece of 1/2" steel with a 1x1/4" slot cut in the middle.  I am using a 1/4" piece of soft copper for the "jet" inside the venturi.  The venturi is located across the approximate center of the can about 5" up from the bottom.  The holes in the can for the pipe have a fairly tight fit.  I have two 1" holes drilled opposite one another at the bottom for fresh air.  I am using a small (tomato paste) can with holes drilled around it for a burn pan.  I supply the air for the venturi from an aquarium air pump that is labeled for 1200 cc/min.  For fuel I am using commercially produced pellets made for smoking foods.  I light the pellets with a propane torch.  I allow the pellets to "free burn" to establish a good amount of burn.  I smother the flame by putting the lid on the can.  The smoldering pellets produce a good, thick smoke.  I hook up the small compressor and a good smoke volume is produced.  After about 5 minutes the smoke begins to thin out.  After 15-20 minutes the smolder is out completely. 

    Leaving the lid partially open will sustain the burning of the fuel but allows too much smoke to escape and not enough into the venturi.  Closing one of the vent holes does not appear to change the time until the burn is smothered. 

    I have tried the following modifications since:

    Moving the 1/4" pipe in and out of the 1/2" pipe creates no appreciable change in the smoke volume or the time to "smother".

    I have created an adapter to attach the air tube to my compressor thereby allowing me to change the volume of air through the venturi-no appreciable change noted. 

    All of the homemade cold smoke generators I have found lack a spec for one component or another...or do not work consistently like mine either.  I have looked at the Smoke Daddy cold smoke generator and can only determine that the air pump is much bigger than mine-something I would have overcome when I created the air compressor adapter. 

    I would appreciate any comments or suggestions. 
  2. smokinal

    smokinal Smoking Guru Staff Member Moderator OTBS Member ★ Lifetime Premier ★

  3. drewed

    drewed Meat Mopper

    Fire needs 3 things to burn, heat, fuel and oxygen.  My guess is that you are not getting enough air to maintain combustion.
  4. lowkey

    lowkey Newbie

    Thanks for your suggestion.  I agree that one of the items you suggest would be easier although I believe they have to be adapted to cold smoking.  After investing a bit of time on this project I hate to give up. I like to solve problems and see things through to completion. 
  5. lowkey

    lowkey Newbie

    I agree.  I have an adequate supply of fuel as it goes out before all fuel is consumed.  I suspect the culprit os oxygen and I am investigating ways to adjust the in-flow of air. 
  6. donr

    donr Smoking Fanatic

    I'm guessing you have an exhaust flow issue since when you pop the top it keeps burning.

    Can you make a rough sketch or take a picture of what you have?

    The a-maz-en products are designed for cold smoking.
  7. I built a generator I saw on youtube that is similar to what you built.  I used a quart paint can.  I had problems keeping the burn going so I drilled one more air intake hole. That solved that problem.  I had issues with too much unburned chip in the bottom.  I cut a piece of aluminium slightly larger than the cans diameter.  Wedging it inside formed a sloped bottom causing the chip slide down and be forced to the burn area at the air intake holes.  Now I get a good complete burn.  Hope this helps   Bill
  8. lowkey

    lowkey Newbie

    Thanks for all of the helpful comments.  I think I have the problem solved.  I drilled many holes in the bottom of the fuel cup and added 4 screws to use as feet and space the bottom of the cup off of the bottom of the can.  That, coupled with attaching a tube from my compressor to allow increased air flow, allow me to sustain a burn.  I enjoy the challenge of solving problems.  This one had me stumped for awhile.  

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