cfm needed for dry washers

[jpdriver1]

afternoon all, I'm considering building my own dry washer based on GG's $65 wastebasket drywasher & using a 12V blower system rather than gas powered. My question is does anyone have an idea of the CFM needed?

thanks in advance

kevin

 

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[kazcoro]

I would say that my Gold Buddy needs between 230 and 260 CFM. Your little plastic one prob needs right around 200.

 

[Clay Diggins]

Way more important than CFM or air velocity is air pressure. A 12 volt fan can easily be designed to produce large CFM of air movement OR high air velocity's. Unfortunately you will find that 12 volt fans can't develop enough air pressure to lift the material in a useful drywasher.

The logical, and historical, solution to the problem is to use a bellows system instead of a fan. Bellows store energy over their intake stroke and release that stored energy as air pressure on their exhaust stroke. It's slower than a "blower" but it can provide you with the air pressure needed to lift pounds of of dirt with a small geared 12 volt motor.

A gas blower relies on horsepower to prevent the stalling of the air mass going through the air box. 12 volt fans just can't develop the type of horsepower needed to develop that pressure. Try hooking up your chosen 12 volt fan to a 4 inch tube and see how much "push" it can develop against the pressure of your hand blocking that 4" output. Now spread that force across several square feet instead of a 4" tube. It's just not gonna happen.

 

[jpdriver1]

thank you -- I'll experiment with different fans --- I suspect that I'll be altering the design to accept bellows in the long run or just invest in a leaf style blower --